Passage Planning C.N. Phase 1

Coastal Navigation

Planning a Passage Between Two Ports

Passage planning from Kolkata to Vizag (Example)

Vessel M.V. Raj at Berth No. 6 NSD drawing a draft of 6.5 m and has to reach Vizag Inner Harbour at berth No. WQ 5 

The Navigating Officer must provide the Master the following:

1. Sea Speed distance or details of open sea passage to next port
2. Distance of Harbour motoring  or distance to be traversed at reduced speed.
3. Fuel, disel, fresh water  and Lub oil on board.
4. ETA to Vizag at normal average speed.
5. Requisitions for Charts, harbor plans, nautical publications if required.

Appraisal

• Admiralty chart catalogue to be consulted to take out small scale chart, large scale charts, harbor plans and sailing directions for the voyage
• Latest cumulative notice is checked to find out if the charts are latest
• Latest quarterly, Weekly notices to Mariners or Cumulative notices are also checked to ensure that all admiralty publications including supplements are relevant and up to date.
• The voyage charts and connected publications are then corrected to the latest weekly “notices to Mariners” on board.
• Relevant Admiralty list of lights are looked into  to k now more details regarding position, characteristics of any Light or construction of any Lighthouse. 
• From admiralty sailing directions the following can also be obtained:

1. Information regarding waters close to shore and underwater dangers
2. The climatic condition of the destination port and meteorological information of the passage from Sandheads to Vizag 
3. Information regarding approaches and anchorages and important ports along the voyage routes
4. Information regarding shelter anchorages and important ports along the route.
5. Information regarding tidal streams.
6. From ALRS Vol 2 get the Navaids along the route and from ALRS Vol 6 obtain port, health  and pilot information.
7. Similarly Guide to Port  Entry and routeing chart for the current month to be studied thoroughly

Planning

Subsequent to the appraisal planning commences. Planning is done on chart and bridge note book

• Take out the smallest scale chart showing both the departure and arrival ports.  Draw the course in order to have a rough idea of the course. 
• Now take out the largest scale chart of the departure port and in this case it will be the approach area to Eastern Channel Light at Sandheads. Plot the initial position about 0.5 miles off the Light vessel and then draw the track to Vizag pilot station.
• Highlight the danger areas, showing areas dangerous for vessel on either side of the course. Safety margin lines on either side of the course line is drawn to make safe water band for the vessel,.
• Sometimes approaches and departure courses are along transit bearing lines.  
• Once the courses are decided, the alteration point need to be placed. The following points should be remembered in selecting an alteration point:

1. Floating points buoys etc cannot be relied upon for alteration of course.
2. Beam bearing of light is preferred as alteration point.
3. Depth contours perpendicular to the course may be used as a cross checking the position of the vessel.
4. 2 RACONS or 2 suitable conspicuous points of land with suitable angular separation (close to 90 deg) may be used for position fixing. 
5. Courses are marked close to the course line. While marking, it must be remembered that important navigational information must not be obscured.

• The voyage charts are then arranged sequentially. 
• Once the charts are marked with information, a brief summary of the voyage is to be written in Bridge Note Book

The Planning can be done in this type of format.

Way Points	Course	Distance	Current		Speed	Stmg time to next W.Pt	ETA Next W.Pt	Freq. of Posn Fixing	Remarks
			Dir	Rate

Execution & Monitoring

The Voyage from Kolkata NSD to Vizag will commence with the Pilot entering the wheelhouse for departure NSD. A Master- Pilot exchange of information must take place prior to commencement of unberthing and pilotage. Again towards the end of the voyage arrival port Pilot will board at Vizag Pilot Station to berth the vessel. Normally the following are discussed in case of Master-Pilot exchange

1. Currents
2. Conditions of wharves
3. Any amendment regarding harbor lights, Local depths, insertion or deletion of wrecks.
4. Peculiar manoeuvre if any
5. Any deviation required in the passage plan
6. Maintaining watch of VHF channels.
7. Use of tugs
8. Readiness of anchors for emergency or manoeuvering
9. Manning the forward station throughout the pilot waters,

Master then informs the OOD accordingly so that the Pilotage is conducted smoothly.

All OOD's during execution of voyage should strictly follow the Plan. They should also consider the reliability of all equipment while executing the plan. All the courses that are laid on charts by Navigating Officer must be actually checked. A watch keeper may find mistakes or may need to alter to some different course due to some reason. In such cases watch keeper must call the Master prior to carrying out such amendment.

In this example the Pilot departs at Sagar Roads and under the guidance of VTMS the vessel proceeds to Eastern Channel Light vessel at Sandheads. From Sandheads vessel will proceed directly to Vizag Pilot Station. The Vizag pilot pilots finally guide the vessel to required berth.

Planning Navigation 

The passage plan should incorporate the following details: 

• Planned track showing the true course of each leg; 
• Leg distances; 
• Any speed changes required en route; 
• Abort/cancellation points for critical manoeuvres; 
• Wheel over positions for each course alteration, where appropriate; 
• Turn radius for each course alteration, where appropriate; 
• Maximum allowable off-track margins for each leg, where appropriate. 

At any time during the voyage, the ship may need to leave the planned leg temporarily at short notice. Marking on the chart relatively shallow waters and minimum clearing distances in critical sea areas is one technique which will assist the OOW when having to decide quickly to what extent to deviate without jeopardizing safety and the marine environment. However, in using this technique, care should be taken not to obscure chart features. On paper charts, only pencil should be used. 

The passage plan should also take into account the need to monitor the ship's position along the route, identify contingency actions at waypoints, and allow for collision avoidance in line with the COLREGS. 

Planning using electronic chart display systems 

Passage planning can be undertaken either on paper charts or using an electronic chart display and information system (ECDIS) displaying electronic navigational charts (ENC), subject to the approval of the flag state administration. Raster chart display systems (RCDS) displaying raster navigational charts (RNC) can be used for passage planning in conjunction with paper charts.

When passage planning using ECDIS, the navigating officer should be aware that a safety contour can be established around the ship. The crossing of a safety contour, by attempting to enter water which is to shallow or attempting to cross the boundary of a prohibited or specially defined area such as a traffic separation zone, will be indicated automatically by the ECDIS while the route is both being planned and executed. 

When passage planning using a combination of electronic and paper charts, particular care needs to be taken at transition points between areas of electronic and paper chart coverage. The voyage involves distinct pilotage, coastal and ocean water phases. Planning within any one phase of the voyage should be undertaken using either all electronic or all paper charts rather than a mixture of chart types. 

Where a passage is planned using paper charts, care should be taken when transferring the details of the plan tan electronic chart display system. In particular, the navigating officer should ensure that: 

• Positions are transferred to, and are verified on, electronic charts of an equivalent scale to that 
• Of the paper chart on which the position was originally plotted; 
• Any known difference in chart datum between that used by the paper chart and that used by the electronic chart display system is applied to the transferred positions; 
• The complete passage plan as displayed on the electronic chart display system is checked for accuracy and completeness before it is used. 
• Transferring route plans to other navigation aids 

Care must be taken when transferring route plans to electronic navigation aids such as GPS, since the ship's position that is computed by the navaid is likely to be in WGS84 datum. Route plans sent to the GPS for monitoring cross track errors must therefore be of the same datum. 

Similarly, in the case of radars, routes and maps displayed on the radar will be referenced to the position of the ship. Care must therefore be taken to ensure that maps and plans transferred to, or prepared on, the radar are created in the same datum as the navaid (typically a GPS) which is connected to, and transmitting positions to, the radar. 

Restricted waters

By comparison with open waters, margins of safety in restricted waters can be critical, as the time available to take corrective action is likely to be limited. 

The manoeuvring characteristics of the ship and any limitations or peculiarities that the ship may have, including reliability problems with its propulsion and steering systems, may influence the route selected through coastal waters. In shallow water particularly, allowance should be made for reduced underkeel clearance caused by ship squat, which increases with ship speed.

Ships' routeing schemes, restricted areas and reporting systems along the route, as well as vessel traffic services, should be taken into account.

Coastal weather bulletins, including gale warnings, and coastal navigational warnings broadcast by coast radio stations and NAVTEX may require changes to be made to the route plan. 

It is important that, when navigation is planned through coastal or restricted waters, due consideration is given to ensuring that the progress of the ship can be monitored effectively. 

Therefore, the route plan should, if possible, be readily available at the main conning position so that continuous monitoring can be performed easily. 

Of particular importance is the need to monitor the position of the ship approaching the wheel over position at the end of a track, and checking that the ship is safely on the new track after the alteration of course. 

The passage plan should include details regarding the required frequency of position-fixing, regardless of whether or not electronic navigation systems are used, and should also include details regarding crosschecking the ship's position by other means, including when electronic navigation systems are used. 

Distinctive chart features should be used for monitoring the ship's position visually, by radar and by echo sounder, and therefore these need to be an integral part of the passage plan. 

Visual monitoring techniques 

Ahead, transits can provide a leading line along which a ship can steer safely. Abeam, transits provide a ready check for use when altering course. At anchor, several transits can be used to monitor the ship's position. 

Bearing lines can also be used effectively. A head mark, or a bearing line of a conspicuous object lying ahead on the track line, can be used to steer the ship, while clearing bearings can be used to check that a ship is remaining within a safe area. 

Radar monitoring techniques 

When radar conspicuous targets are available, effective use can be made of radar clearing bearings and ranges. 

Ships with good athwartship track control can use clearing bearings to monitor the advance of a ship towards a wheel over position, while parallel indexing can be used to check that the ship is maintaining track and not drifting to port or starboard.  

Navigation in coastal waters

Have the following factors been taken into consideration in preparing the passage plan?

• Advice/recommendations in Sailing Directions
• Ship’s draught in relation to available water depths 
• Effect of squat on underkeel clearance in shallow water
• Tides and currents
• Weather, particularly in areas prone to poor visibility
• Available navigational aids and their accuracy 
• Position-fixing methods to be used
• Daylight/night-time passing of danger points
• Traffic likely to be encountered – flow, type, volume
• Any requirements for traffic separation/routeing schemes
• Ship security considerations regarding piracy or armed attack
• Are local/coastal warming broadcasts being monitored?
• Is participation in area reporting systems recommended including VTS?
• Is the ship’s position being fixed at regular intervals?

Has equipment been regularly checked/tested, including:

• Gyro/magnetic compass errors
• Manual steering before entering coastal waters if automatic steering has been engaged for a prolonged period
• Rader performance and radar heading line marker alignment 
• Echo sounder
• Is the OOW prepared to use the engines and call a look-out or a helmsman to the bridge?
• Have all measures been taken to protect the environment from pollution by the ship and to company with applicable pollution regulations?

Meteorological conditions

Anticipated meteorological conditions may have an impact on the ocean route that is selected. 

For example: 

• Favorable ocean currents may offer improved overall passage speeds offsetting any extra distance travelled; 
• Ice or poor visibility may limit northerly or southerly advance in high latitudes; 
• Requirements for ballast water exchange may cause the route selected to be amended in view of forecast or anticipated conditions; 
• The presence of seasonal tropical storm activity may call for certain waters to be avoided and an allowance made for searoom. 

Details of weather routeing services for ships are contained in lists of radio signals and in Volume D of the World Meteorological Organization (WMO) Publication. Long-range weather warnings are broadcast on the SafetyNET Service along with NAVAREA navigational warnings as part of the World-Wide Navigational Warning Service (WWNWS). 

Weather Routeing

The mariner planning a transoceanic passage can select either the shortest route, or the quickest route at a given speed, or the most suitable route from the point of view of weather or any particular requirements.

Climatic condition, however, such as the existence of currents or the prevalence of wind, sea or swell form certain directions, may lead to the selection of a longer climatological route along which a higher speed can be expected to be made good.

Weather routing is done by collection of oceanographical and meteorological data, and data received from weather satellites and good forecasting techniques. The mariner’s first resources for route planning in relation to weather are the Pilot Chart Atlases, the Sailing Directions (Planning Guides), and other climatological sources such as historical weather data tables. These publications give climatic data, such as wind speed and direction, wave height frequencies and ice limits, for the major ocean basins of the world. They may recommend specific routes based on probabilities, but not on specific conditions.

Weather routing makes use of the actual weather and the forecast weather in the vicinity of the anticipated route. By using weather forecasts to select a route, and then modifying the route as necessary as the voyage proceeds and decide the optimum route.

Optimum ship routing is the art and science of developing the “best route” for a ship based on the existing weather forecasts, ship characteristics, ocean currents and special cargo requirements. For most transits this will mean the minimum transit time that avoids significant risk to the vessel, crew and cargo. Other routing considerations might include passenger comfort, fuel savings or schedule keeping. The goal is not to avoid all adverse weather but to find the best balance to minimise time of transit and fuel consumption without placing the vessel at risk to weather damage or crew injury.

The ship routing agency, acting as an advisory service, attempts to avoid or reduce the effects of specific adverse weather and sea conditions by issuing initial route recommendations prior to sailing. Adverse weather and sea conditions are defined as those conditions which will cause damage, significant speed reduction, or time loss.

Weather routing can be classified as follows

• Climatological Routing
• Strategic Routing
• Tactical Routing

A significant advantage of weather routing accrues when:

• The passage is relatively long, about 1,500 miles or more;
• The waters are navigationally unrestricted, so that there is a choice of routes; and
• Weather is a factor in determining the route to be followed.

Ship and cargo characteristics have a significant influence on the application of ship weather routing. Ship size, speed capability, and type of cargo are important considerations in the route selection process prior to sailing and the surveillance procedure while underway. A ship’s characteristics identify its vulnerability to adverse conditions and its ability to avoid them.

Ship performance curves (speed curves) are used to estimate the ship’s Speed of Advance (SOA) while transiting the forecast sea states. The curves indicate the effect of head, beam, and following seas of various significant wave heights on the ship’s speed.

Each vessel will have its own performance curves, which vary widely according to hull type, length, beam, shape, power, and tonnage.

With the speed curves it is possible to determine just how costly a diversion will be in terms of the required distance and time. A diversion may not be necessary where the duration of the adverse conditions is limited. In this case, it may be better to ride out the weather and seas knowing that a diversion, even if able to maintain the normal SOA, will not overcome the increased distance and time required.

Based on input data for environmental conditions and ship’s behaviour, route selection and surveillance techniques seek to achieve the optimum balance between time, distance, and acceptable environmental and Seakeeping conditions.

Although speed performance curves are an aid to the ship routing agency, the response by mariners to deteriorating weather and sea conditions is not uniform.

Environmental factors of importance to ship weather routing are those elements of the atmosphere and ocean that may produce a change in the status of a ship transit. In ship routing, consideration is given to wind, seas, fog, ice, and ocean currents.

Optimum routing is normally considered attained if the effects of wind and seas can be optimized.

Optimum Ship's Routeing

Weather routing is an important aspect of navigating across the oceans. It requires planning and study. You should keep in mind the additional cost of fuel and time delay involved in taking a longer route as well as the extent of damage which you may face if opting for a shorter route. 

Optimum ship routing is the process of developing the “best route” for a ship, based on the existing weather forecasts, ship characteristics and cargo requirements. This implies adopting Optimum Ship Routing, the transit time shall be minimum and at the same time it shall avoid any significant risks to the vessel, crew and cargo. This does not necessarily mean that all the adverse weather will be avoided and you will have a mirror like sea for transit, but we can find the best balance to minimise time of transit and fuel consumption, without taking any risk of damage or crew injury. 

Route planning normally will start by appraisal, which involves reviewing the appropriate Pilot Chart atlases and Sailing Directions to determine the normal weather patterns, weather risks and prevailing ocean currents. The Routing Service then reviews recent weather patterns and weather forecast charts to determine the most likely conditions during the course to the voyage. Ship performance curves, also known as speed curves, are used to estimate the ship’s speed of advance while transiting the forecast sea states. The curves indicate the effect of head, beam, and following seas of various significant wave heights on the ship’s speed.

Graph showing speed curves

The above figure is a performance curve prepared for a 16 knot vessel. A diversion may not be necessary where the duration of the adverse conditions is limited. In this case, it may be better to ride out the weather and seas knowing that a diversion will not overcome the increased distance and time required. At other times, the diversion track is better because it avoids an area of bad weather and sea conditions, at the same time being able to maintain good speed of advance, even though the distance to destination is increased. 

A preliminary routing message is transmitted to the Master of a vessel prior to departure, an initial route proposed, with a detailed forecast of expected storm tracks. The agency gives reasons behind the recommendation and also the expected weather conditions to be encountered along that route. This allows the Master to better plan his route and offers an opportunity to communicate with the service any special concerns that he or she might have due to special cargo requirements or ship condition. 

The ship's route to the destination port is then planned by the navigating officer in consultation with all watchkeeping officers. The passage planning is done as per the guidelines laid down and approval for the same is obtained from the Master. The intended plan of the vessel is also conveyed to the routing agency. 

Once the vessel departs, the passage progress is monitored closely with weather and route updates sent as needed. 

Ship routing is also referred to as weather routing, optimum track ship routing, and meteorological navigation. Routing offices compute the initial route based on the long-range weather forecast, but maintain a daily plot of both the ship and the storm positions. If conditions warrant, an amended route is sent to the ship's Master based on the latest weather changes and the passage plan is amended if necessary.

Factors affecting weather routeing 

Environmental factors play a major role in the ship’s weather routing. These elements of the atmosphere and ocean may produce a change in the time status of a ship transit. In ship routing, consideration is given to wind, seas, fog, ice, and ocean currents. While all of the environmental factors are important for route selection and surveillance, optimum routing is obtained by calculating the effects of wind and seas. 

Wind

The effect of wind speed on ship performance is difficult to determine. In light winds of less than 20-knots, ships lose speed in headwinds and gain speed slightly in following winds. In case of higher wind speeds, ship speed is reduced in both head and following winds. This is due to the increased wave action, which even in following seas results in increased drag which is caused due to repeated use of the helm for steering corrections, and indicates the importance of sea conditions in determining ship performance. 

In dealing with wind, it is also necessary to know the ship’s windage area. In case of a container ship or a car carrier, the windage area is comparatively more, hence high winds will have a greater adverse effect than on a fully loaded tanker of similar length. When you approach a berth, this effect is most noticeable. 

Wave Height 

Wave height is the major factor affecting ship performance. Due to wave action ship motions are generated which reduce propeller thrust and cause increased drag from steering corrections. Wave height and direction also have the same effect on ship speed as to that of wind. Head seas reduce ship speed, while following seas increase ship speed slightly. But this happens only to a certain point, beyond which they retard it. In heavy seas, exact performance may be difficult to predict because of the adjustments to course and speed for ship handling and comfort. Although the effect of sea and swell is much greater than wind, it is difficult to separate the two in ship routing. Every wave forecast is produced using an initial state obtained by blending wind and wave data into a numerical model. Usually data are gathered into six hour windows centered around the assumed times. At each time incremental sea spectra are calculated. This is done using an action balance equation where the evolution of the energy spectrum of the waves is forced by three contributory effects:

• Energy input from forcing wind;
• Nonlinear wave-wave interaction which transfers energy between long and shorter wavelength waves;
• Energy dissipation from breaking waves.

The wind field is used to force the wave model output which is then corrected locally with measurements of wave height, period and direction, at each time step by drawing the model sea state towards the observed values by interpolation scheme. 

Ocean Currents 

Ocean currents do not present a significant routing problem, but they can be a determining factor in route selection and diversion. It is more effective when the points of departure and destination are at relatively low latitudes. What needs to be considered here is the difference in distance between a great-circle route and a route selected for optimum current, with the expected increase in vessel speed from the following current. Also a decreased probability of a diversion for weather and seas at the lower latitude shall be taken into account. 

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Direction and speed of ocean currents are more predictable than wind and sea, but some variability can be expected. Major ocean currents can be disrupted for several days by very intense weather systems such as hurricanes. 

Fog

Fog may not affect ship's performance directly but, should be avoided as much as feasible, in order to maintain normal speed in safe conditions. During fog, the vessel needs to reduce speed for safety concerns and that may increase the transit time. Moreover, extra lookouts are required to be posted, which requires more manpower. Extensive areas of fog during summertime can be avoided by selecting a lower latitude route than one based solely upon wind and seas. Although the route may be longer, transit time maybe less due to not having to reduce speed in reduced visibility. 

North Wall Effect 

At certain areas after passage of a strong cold front or behind a developing coastal low pressure system, higher waves and confused seas result. This phenomenon is called the “North Wall Effect, “referring to the region of most dramatic temperature change between the cold water to the north and the warm Gulf Stream water to the south. Thus, a ship that is labouring in near-gale force northerly winds and rough seas, proceeding on a northerly course, can suddenly encounter storm force winds and dangerously high breaking seas. Numerous ships have foundered off the North American coast in the approximate position of the Gulf Stream’s North Wall. A similar phenomenon occurs in the North Pacific near the Kuroshio Current and off the southeast African coast near the Agulhas Current. 

Ice 

The problem of ice is twofold; floating icebergs and deck ice. The presence of icebergs requires more attention into the job of navigation where you have to follow procedures for ice navigation. Hence, areas of icebergs or pack ice should be avoided because of the difficulty of detection and the potential for collision. Deck ice may be more difficult to contend with from a ship routing point of view because it is caused by freezing weather, associated with a larger weather system. It causes significant problems with the stability of small ships. On the other hand in case of a large ship it is more of a nuisance factor causing slippery deck surface and hampering free movement or any maintenance on deck. Not to mention the damage it may cause to deck hydraulic machinery. Also fresh water, sanitary water and deck service water tend to freeze in the pipes preventing flow of water through them and sometimes even bursting them. 

Latitude 

Generally, the higher the latitude of a route, even in the summer, the greater is the problems with the environment. Certain operations should benefit from seasonal planning as well as optimum routing. For example, towing operations north of about 40° latitude should be avoided in non-summer months if possible. When a great-circle track passes through very high latitudes the vessel is likely to experience very low atmospheric temperatures which should be preferably avoided.

Types of Recommendations 

Due to the substantial increase in the movement of world tonnage and considerable increase in the number of ships, a lot of risks involving life and property are at stake. To minimise the losses due to weather calamities, the shipping companies do not mind paying for professional advice on weather routing. This has resulted in the increase of a number of weather routing agencies around the world. The aim of all these is to provide the latest weather updates and assist the Master with the best possible routes across the ocean in a minimum time. 

The weather routing agencies have all the latest information with to ocean weather. They have state of the art equipment which gives them minute to minute information of any moving tropical storms, low pressures, turbulence or unstable weather. They keep sending the updated weather reports and recommended routes to the Master as and when found necessary. The Master after assessing the on-scene situation and considering the safety of the vessel should decide on implementing the recommended alteration. The information updates are in different formats depending upon the gravity of the situation. Some examples are mentioned in the below media. 

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Initial Route Recommendation

This monitoring is a continuous process, maintained until the ship arrives at its destination. Initial route recommendations are made considering experience, climatology, weather and sea state forecasts, operational concerns, and the ship’s seagoing characteristics. A planning route provides a best estimate of a realistic route for a specific transit period. Long range planning routes are based more on seasonal and climatological expectations than the current weather situation. These recommendations are likely to be revised near the time of departure to reflect the current weather pattern. An initial route recommendation is more closely related to the current weather patterns by using the latest dynamic forecasts than are the planning route recommendations. These, too, are subject to revision prior to sailing, if weather and sea conditions warrant.

Adjustment of Departure

The initial route is not revised, only the timing of the ship’s transit through an area with currently unfavorable weather conditions is altered so that the potentially hazardous situation can be avoided. This is particularly useful where there is no optimum route for sailing at the originally scheduled time.

Diversion 

Ship’s speed is expected to be reduced by the encounter with the heavy weather, hence in diversion the distance to destination is increased in attempting to avoid the adverse weather, but this is partially overcome by being able to maintain near normal speed which otherwise would not have been possible. Diversions are also recommended where satisfactory weather and sea conditions are forecast on a shorter track.

Adjustment of Speed of Advance: 

This is also an effective means of maintaining maximum ship operating efficiency, while not diverting from the present ship’s track. By adjusting the speed of advance a major weather system can sometimes be avoided with no increase in distance. 

Evasion 

The recommendation for evasion is an indication that the weather and sea conditions have deteriorated to a point where ship handling and safety are the primary considerations and progress toward destination has been temporarily suspended, or is at least of secondary consideration. 

There is also a weather advisory which is nothing but a transmission sent to the ship advising the Master of expected adverse conditions, their duration, and geographic extent. It is initiated by the ship routing agency as a service and an aid to the ship. The best example of a situation for which a forecast is helpful is when the ship is currently in good weather but adverse weather is expected within 24 hours, for which a diversion has not been recommended, or a diversion where adverse weather conditions are still expected. This type of advisory may include a synoptic weather discussion, and a wind, sea, or fog forecast. The ability of the routing agency to achieve optimum conditions for the ship is aided by the Master adjusting course and speed where necessary for an efficient and safe passage. At times, the local sea conditions may dictate that the Master take independent action.

Hazardous Weather 

Geographical Areas Associated with Heavy Weather 

Introduction 

Heavy weather can be encountered in any part of the world. In some ocean regions unsettled weather is a regular phenomenon, while in other regions it occurs seasonally. If we have adequate knowledge about the region we are sailing in, we can be prepared to face heavy weather. Even an age modern technology, areas such as the Bay of Biscay, the North Atlantic and the North Pacific ocean require planning and preparation. 

Objective 

On completion of this sub-topic, you should be able to: 

• List the ocean regions associated with hazardous weather. 

Almost all the ocean regions of the world are associated with some form of bad weather. Given below are some of the areas on the globe which form a major portion of world's ocean trading and are also long known to be closely associated with heavy weather. 

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Bay of Biscay

It is a wide inlet of the North Atlantic Ocean indenting the coast of western Europe. Parts of the continental shelf extend far into the bay, resulting in fairly shallow water in many areas and thus cause the rough seas for which the region is known. The Bay of Biscay is home to some of the Atlantic Ocean's fiercest weather. Large storms occur in the bay, especially during the winter months. Up until recent years it was a regular occurrence for merchant vessels to founder in Biscay storms, and many lives were lost. Improved ships and weather prediction have reduced the toll of the storms.

North Atlantic 

Tropical cyclones can affect the entire North Atlantic Ocean in any month. However, they are mostly more dangerous south of about 35°N from June through November; August, September, and October are the months of highest incidence. Further, the cold Labrador current from the Arctic meet the warm Gulf Stream coming from east coast of United States. This results in the formation of thick fog near the Grand Banks of New Foundland, thus greatly affecting the navigation in those areas. 

The other major currents in the North Atlantic being the Canary Current which flows off Northwest Africa and the North Atlantic Drift which divideds partly to northern Europe and partly to the east Atlantic.

The hurricanes grow due to release of heat when vapor evaporated from the warm ocean is lifted and condensed to bands of heavy showers. Hurricanes may persist for more than a week. Thus, they frequently move clockwise around the periphery of the North Atlantic high-pressure belt and into the prevailing westerlies, often ending up in the Icelandic area.

South Atlantic

Across central Africa and out into the Atlantic long periods of calm are frequent. Winds and storms made the South Atlantic difficult to sail. While sailing in the South Atlantic, the trade winds blew in the contrary direction, pushing ships backwards. The presence of powerful matching currents made matters worse. These winds were strong as they blew unobstructed, due to the absence of any land mass in the South Atlantic.

Rather than fight these winds, Portuguese sailors would have to sail westward almost all the way across the South Atlantic to Brazil before turning to the east, to the southern tip of Africa. Finally in order to sail back across the Atlantic from the bulge of South America to the tip of southern Africa was difficult because of strong winds, powerful intersecting currents, and storms with winds up to 180 kilometers per hour. The prominent currents in South Atlantic are the Brazil current which flows along the east coast of South America and the Benguela current flowing in a northerly direction along the west coast of Africa.

The Indian Ocean

It is distinguished by the presence of seasonally reversing currents that flow between the Bay of Bengal and the Arabian Sea. The Summer Monsoon current flows eastward during the summer monsoon (June–September) followed by transition period in October and November. Similarly from December to March the Winter Monsoon Current flows westward which causes the winter monsoon followed by the transition period in April and May. The summer monsoons bring severe weather to the Arabian Sea and the west Indian Ocean. Over the waters west of longitude 100°E, to the east African Coast, most of the tropical storms in the Indian Ocean develop. Gale-force winds are infrequent in the Gulf. Gales of 34 to 40 knots are experienced on about 11 days per month in the 52-54E longitude zone. A marked increase in wave and swell heights is also experienced as one passes eastward out of the Gulf of Aden and into the western Arabian Sea. The primary currents in the Indian Ocean are the Agulhas current flowing towards the Cape of Good Hope along east Africa and the Mozambique current passing east of Mozambique.

North Pacific

The typhoons in North Pacific are among the largest and most intense tropical cyclones in the world. Each year an average of five generate maximum winds over 130 knots, having circulations covering more than 600 miles in diameter. Most of these storms form east of the Philippines, and move across the Pacific toward the Philippines, Japan, and China; a few storms form in the South China Sea.

They define a feature known as the Aleutian Low. Due to presence of various thermal gradients and readily available moisture, the area can have several systems active at the same time. The placing of a major topographical barrier, in the form of the western cordillera of North America, across the path of the westerlies effectively halts the continued eastward propagation of many of these systems. The major currents in north Pacific are the warm Kuroshio which flows northward over the east China sea and the southbound cold Oyashio passing north east of Japan. The southbound cold Californian current passes off west coast of north America.

South Pacific

The season extends from about December through April, although storms can form in any month. Activity is widespread in January and February, and it is in these months that tropical cyclones are most likely to affect Fiji, Samoa, and the other islands. Westerly winds blow thousands of miles across the Pacific Ocean toward South America. When they reach land and run into the Andes Mountains, they are forced to turn north. The wind causes the water at the ocean surface to move perpendicular to it, away from the coast, because of a process called Ekman transport. The other major currents in South Pacific are the warm East Australian currents and the cold Peru currents.

Conditions for Hazardous Weather

Introduction

Hazardous weather can develop suddenly. There are reasonable indications by which we can conclude that heavy weather may be developing. Being an officer on the bridge, it is imperative that you are able to to recognise the symptoms of developing unstable weather.

On many summer days when the sky is clear in the morning, cumulus clouds develop during midday and can cover much of the sky by mid-afternoon, when the day's maximum temperature is reached. These cumulus clouds can develop further into towering cumulus and cumulonimbus clouds if the atmosphere is conditionally unstable, bringing showers and thunderstorms to an area where the morning had been clear and sunny. Such explosive developments occur in a conditionally unstable atmosphere, with the lifting triggered by solar heating. Several of these storms actually produce tornadoes.

Wind is generally accelerated from areas of high pressure to areas of low pressure. This is due to density, temperature and moisture differences between two air masses. Since stronger high pressure systems contain cooler or drier air, the air mass is more dense and flows towards areas that are warm or moist. The stronger the pressure difference, or pressure gradient, between a high pressure system and a low pressure system, the stronger the wind. Thus, stronger areas of low pressure are associated with stronger winds. 

The media below shows the formation of a hurricane associated with a typical hazardous weather.

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The Coriolis force, caused by the earth's rotation, gives winds within low pressure systems a counterclockwise circulation in the northern hemisphere and clockwise circulation in the southern hemisphere. Friction with land slows down the wind flowing into low pressure systems and causes wind to flow more inward, toward the low pressure. A low pressure area is commonly associated with inclement weather, while a high pressure area is associated with light winds and fair skies.

There are numerous and various factors which determine weather. The weather service can be improved by increasing knowledge about the same. However, the ability to forecast is acquired through study and long practice, and therefore the services of a trained meteorologist should be utilized whenever available. The value of a forecast is increased if one has access to the information upon which it is based, and understands the principles and processes involved. Knowing the various types of weather which may be experienced is equally important as are the consequences and possibilities which are likely to occur due to its effect. At sea, reporting stations are unevenly distributed. Some areas are largely accessible while some, in the southern hemisphere, are feebly covered. Under these conditions, the locations of highs, lows, fronts, etc., are imperfectly known, and their very existence may even be in doubt. At such times the mariner who can interpret the observations made from his own vessel may be able to predict weather for the next several hours more reliably than a trained meteorologist ashore.

Ice

The safety of ships operating in the harsh, remote and vulnerable polar areas and the protection of the pristine environments around the two poles have always been a matter of concern for IMO and many relevant requirements, provisions and recommendations have been developed over the years. 

Trends and forecasts indicate that polar shipping will grow in volume and diversify in nature over the coming years and these challenges need to be met without compromising either safety of life at sea or the sustainability of the polar environments. 

Ships operating in the Arctic and Antarctic environments are exposed to a number of unique risks. Poor weather conditions and the relative lack of good charts, communication systems and other navigational aids pose challenges for mariners. The remoteness of the areas makes rescue or clean up operations difficult and costly. Cold temperatures may reduce the effectiveness of numerous components of the ship, ranging from deck machinery and emergency equipment to sea suctions.  When ice is present, it can impose additional loads on the hull, propulsion system and appendages.

The International code of safety for ships operating in polar waters (Polar Code) covers the full range of design, construction, equipment, operational, training, search and rescue and environmental protection matters relevant to ships operating in the inhospitable waters surrounding the two poles.

Category A ship means a ship designed for operation in polar waters in at least medium first-year ice, which may include old ice inclusions. This corresponds to vessels built to the International Association of Class Societies (IACS) Polar Ice classes PC1 to PC5.

Category B ship means a ship not included in category A, designed for operation in polar waters in at least thin first-year ice, which may include old ice inclusions. This corresponds to vessels built to the IACS Polar Ice classes PC6 and PC7.

Category C ship means a ship designed to operate in open water or in ice conditions less severe than those included in categories A and B. This corresponds to vessels of any Baltic Ice class or with no ice strengthening at all.

Procedures when navigating in ice

Operations in Ice 

DEFINITIONS

• Safe speed – maximum possible speed of the ship movement under certain ice conditions when the hull/ice interaction in the channel does not result in the hull damage.
• Attainable speed – maximum speed of the ship movement under certain ice conditions she can develop and maintain using the full power of main engines.
• Admissible speed – maximum speed of the ship movement under certain ice conditions corresponding to either safe or attainable speed whichever is lower.
• Minimum safe distance – minimum distance between ship and the icebreaker sailing in front or other ship forming part of a composite convoy equal to the braking track of ship in the channel in case of a sudden stop.
• Ice concentration – ratio between the area of floes in the zone of their relatively uniform distribution and the total area of this zone expressed in numbers (by 10-point scale). For instance, ice concentration of 7-8 means that 70-80 % of the channel area is covered with ice and the remaining 20-30 % is open water.
• Ice pressure – decrease of the distance between separate ice floes as a result of the wind and current action leading to the increase of concentration and drifting ice compacting (expressed in numbers by 3-point scale).
• Ice ridges – concentration of hummocks of all types on the ice surface (ex-pressed in numbers by 5-point scale).
• Ice cake – ice floes of less than 20 m in diameter.
• Medium ice floes – ice floes of 100-500 m in diameter.
• Large ice floes – ice floes of 500-2000 m in diameter.

Information required for determination of admissible speed

Ship’s trim

• Loaded;
• Under ballast;

Type of navigation

• Independent;
• Under icebreaker escort;

Ice conditions

• Level compact ice;
• Large ice floes (500-2000 m);
• Medium ice floes (100-500 m);
• Ice cake (less 20 m);

Additional ice factors

• Ice pressure;
• Hummocks;

Ice thickness

• Current value.

Information required for determination of safe distance

• Ship’s trim – loaded, under ballast;
• Concentration of ice in the channel – 5-6, 7-8, 9-10;
• Ice thickness – current value;
• Speed – current value.

The safe distance is determined for the event of emergency braking of ship with propeller reversing during the movement in the channel, when due to a suddenly emerged ice obstacle an icebreaker or ship moving ahead loses way until the full stop. The ship should be capable of killing the way and stopping in order to avoid collision.

Information required for the determination of minimum admissible curvature radius of ice channel:

• Speed of a ship – 5-6 knots;
• Channel width – current value.

Curvature radius of ice channel is determined using a diagram establishing dependence between this parameter and width of a channel.

General rules

First principle of operating in ice: Ice is an obstacle to any vessel, even an icebreaker. The inexperienced ice navigator is advised to develop a healthy respect for the latent power and strength of ice in all its forms. However, well-found vessels in capable hands can operate successfully in ice-covered waters.

The first principle of successful passage through ice is to maintain freedom of manoeuvre. Once a vessel becomes trapped, she goes wherever the ice goes. Operating in ice requires great patience and can be a tiring business with or without icebreaker escort. The ice-free long way round a difficult area whose limits are known is often the quickest and safest way. 

Best practice for operating in ice: When navigating in ice, the following golden rules apply:

• Keep moving, even if very slowly
• Try to work with the ice movement and not against it
• Excessive speed leads to ice damage
• Always attempt to achieve a right-angle approach to any floe
• Ensure rudder is amidships before making any sternboard
• Avoid anchoring in moving close pack ice 

Entering the Ice

The route recommended by the Ice Operations Officer through the appropriate reporting system is based on the latest available information and Masters are advised to adjust their course accordingly. The following notes on ship-handling in ice have proven helpful:

• Do not enter ice if an alternative, although longer, route is available.
• It is very easy and extremely dangerous to underestimate the hardness of the ice.
• Enter the ice at low speed to receive the initial impact; once into the pack, increase speed to maintain headway and control of the ship.
• Be prepared to go "Full Astern" at any time.
• Navigation in pack ice after dark should not be attempted without high-power searchlights which can be controlled easily from the bridge; if poor visibility precludes progress, heave to and keep the propeller turning slowly as it is less susceptible to ice damage than if it were completely stopped.
• Propellers and rudders are the most vulnerable parts of the ship; ships should go astern in ice with extreme care - always with the rudder amidships.
• All forms of glacial ice (icebergs, bergy bits, growlers) in the pack should be given a wide berth, as they are current-driven whereas the pack is wind-driven.
• Wherever possible, pressure ridges should be avoided and a passage through pack ice under pressure should not be attempted.
• When a ship navigating independently becomes beset, it usually requires icebreaker assistance to free it. However, ships in ballast can sometimes free themselves by pumping and transferring ballast from side to side, and it may require very little change in trim or list to release the ship.

The Master may wish to engage the services of an Ice Pilot, Ice Advisor or Ice Navigator in the Arctic.

Navigating in Polar Regions

The art of piloting and navigating in the polar regions has generally been considered to present numerous difficult problems. Actually, apart from the special hazards offered by growlers and bergs during periods of low visibility and fog, the basic problems remain essentially the same as those encountered when operating over extended periods in lower latitudes.

Signs of proximity of ice

Ice blink

When passing through open water where no ice is visible, it is sometimes possible to detect the presence of ice in the neighborhood by certain signs, as follows:

1. The receipt of a return signal (pip or echo) by a vessel employing radar or sonar will usually give positive indication of the proximity of large icebergs.
2. Iceblink, the reflection of ice on the lower clouds, is the indication that has been most used by experienced pilots. As mentioned previously, the albedo of sea ice or a snow surface is much higher than that of a water surface. Much more sunlight is therefore reflected upwards from snow or ice and diffused by haze, dust, or water particles in the lower atmosphere. Iceblink thus appears as a diffuse white patch, more or less bright, on visible clouds, or as brilliant scintillating strips on the horizon. There is no iceblink on a sunny day with a clear blue sky. Slight snow flurries cause a more definite iceblink.
3. The appearance of isolated fragments of ice often points to the proximity of larger quantities of ice,
4. In late spring and summer, fog often indicates the edge of the ice.
5. In fog, white patches indicate the presence of ice at a short distance.
6. Icebergs cracking, or pieces falling into the sea. make a noise like breakers or distant gunfire. However, the sound is faint and one must usually be quite close to the berg to hear it.
7. Absence of swell or motion of the water in a fresh breeze is a good sign of ice to windward, if the vessel is not in the vicinity of land.
8. Lowering of the temperature of the surface layer of sea water, or the lowering of the air temperature, may indicate that the ship has entered waters where ice is likely to be encountered. The converse does not apply; nor should maintenance of sea and air temperatures be taken to mean that no ice is about,
9. The presence of walruses, seals, or birds may indicate the proximity of the ice, if far from land. The Antarctic petrel is normally seen only within about 400 miles of the ice edge. The appearance of the snow petrel is an almost certain indication that pack ice is within a few hours' steaming.

Signs of open water

Water Sky

1. Dark patches on low clouds, sometimes almost black in comparison with the clouds in general, indicate the presence below them of open water. This is known as water sky. Like iceblink, this phenomenon depends on the greater absorption of sunlight by water than by ice or snow, and the subsequent diffusion of the reflected light in the lower atmosphere. When the air is very clear, it tends to be suppressed.
2. Dark spots in fog give a similar indication, but are not visible for as great distances as reflections on clouds.
3. A dark band on a cloud at a high altitude indicates the existence below this line of small patches of open water which may connect with a larger distant area of open water.
4. The sound of a surge in the ice indicates the presence of large expanses of open water in the immediate vicinity.

The best weather conditions for navigating in the ice are fine days with a clear horizon and atmosphere, but with the sky covered with an even layer of clouds. Then, as stated previously, the iceblink appears in light markings on the under surface of the clouds above it. Where leads of open water occur in the pack, the iceblink is sharply broken, with water sky appearing almost black by contrast.

If when approaching ice there is darkness on the horizon beyond a light sky, it indicates that there is open water or land beyond the ice, in some cases 40 miles or more beyond the visible horizon. If thin, dark streaks on the sky are observed, the existence of leads is indicated. If there are no dark streaks, a vessel should steer for the place where the iceblink is dullest. The clarity of the blink is increased after a fresh fall of snow, since the reflection on the sky will be whiter from snow than from ice. With a cloudless sky there can be no iceblink, though there may be a yellow or white haze or glare to indicate the presence of ice. However, with a cloudless sky there may be abnormal refraction, which raises the horizon and enables the observer to see the ice at a greater distance than would normally be possible. The image of the ice or areas of open water, or a mixture of the two, may be seen as an erect or inverted image, or both images may be seen at once, one above the other. In this case the erect image is the higher of the two, which are usually in contact. Allowance must be made for the fact that refraction causes the apparent dimensions of ice to increase, sometimes so as to make bergy bits appear like icebergs. Where there is open water there will be seen a dark blue color, toward which the vessel should steer.

Ice identification: Mariners should note that, before attempting any passage through ice, it is essential to determine its type, thickness, hardness, floe size and concentration. This can only be achieved visually.

It is very easy and extremely dangerous to underestimate the hardness of ice.

After a snow fall, ice thickness can be very difficult to identify. Hence, mariners should exercise due diligence, based on experience, when making a passage through ice.

Ice is seldom uniform. There can be every type/age of ice among drift ice.

Changes in ice conditions: Ice moves continually under the influence of wind and current; floating ice is much influenced by the wind. With a change of wind, ice conditions can change completely, often within hours, depending on the concentrations.

Ice fuses when the temperature falls below freezing. An area of separate ice floes and loose fragments can quickly turn into a solid mass of ice and pose serious problems, even for icebreakers.

When practicable, a lookout from aloft will frequently detect both the best strategic route to utilise, and open water not distinguishable from the bridge. However, the tactical control of both track and engine movements/power, especially if not available aloft, remains on the bridge. 

Considerations before entering ice 

Factors: Ice should not be entered if an alternative, although longer, route is available. Before deciding to enter the ice the following factors need to be considered:

• Latest ice report detailing the type and concentration of the ice in the area
• Time of year, weather and temperature
• Area of operation
• Availability of ice manoeuvring modes from all equipment and machinery spaces
• Availability of icebreakers
• Availability of any airborne support
• Availability of potential mutual support/advice from other vessels in the area
• Vessel's ice class in relation to the type of ice expected
• State of hull, machinery and equipment, and quantity of bunkers and stores available 
• Draught, with respect to any ice strengthened belt, and depth of water over the propeller tips and the rudder
• Ice experience of the person in charge on the bridge

Impact on passage of age and thickness of ice: Modern steel vessels can make passage on the original planned route through thin, new ice. Thick first-year ice or old ice that cannot be negotiated safely, due to the vessel's ice classification, requires the prudent mariner to stop and wait until either conditions improve with a change of wind or tide, or an icebreaker becomes available. 

Navigation in reduced visibility: At night or in reduced visibility when passing through fields of drift ice, speed must be reduced or the vessel stopped until the mariner can distinguish and identify the ice ahead. Navigation in drift ice in darkness should only be attempted with the aid of well-positioned searchlights to assist in the interpretation of the radar picture.

Ice of land origin should be given a wide berth: All forms of glacial ice and dirty ice broken away from coastal regions should be given a wide berth. Icebergs are usually current-driven while the ice field will have a wind-drift component.

With a strong current icebergs may travel upwind. Under these circumstances, open water will be found to leeward and pressured pack ice will be found to windward of the iceberg. 

Similar conditions have been observed with a weak current and a strong wind, when the floes overtaking an iceberg were heaped up to windward, while a lane of open water lay to leeward of the iceberg.

Any vessel, observing such situations, and experiencing difficulty in advancing through the prevailing drift-ice concentrations, should monitor the relative situation very closely, and make every available effort to manoeuvre to the leeward side of the berg.

When navigating in pack ice, advantage may be taken of leads created by the relative movement of icebergs through the pack ice.

Using leads: When navigating in pack ice every opportunity should be taken to use all leads and any - ' open water available, however, without icebreaker support it is unwise to follow a shore lead with an onshore wind blowing or expected. A flaw lead is not as hazardous in offshore winds but is not recommended. A vessel stopped in ice close inshore should always be pointed to seaward unless it is intended to anchor.

Making an entry: The following principles govern entry into the ice: 

• Entry should not be attempted where the existence of pressure is evident from hummocking and rafting
• The ice should be entered from leeward, if possible, as the windward edge of an ice field is more compact than the leeward edge, and wave action is less on the leeward edge
• The ice edge often has bights separated by projecting tongues. By entering at one of the bights, the surge will be found to be least
• Ice should be entered at very low speed and at right angles to the ice edge to receive the initial impact, and once into the ice speed should be increased to maintain headway and control of the vessel 

Speed in ice: The force of the impact on striking ice depends on the tonnage and speed of the vessel. It varies as the square of the speed. Speed in ice therefore requires careful consideration. If a vessel goes too slowly, she risks being beset; and if she goes too fast, she risks damage from collision with floes.

Where concentrations of ice vary, and a vessel passes from close pack ice through patches of open drift ice or open water and back to close pack ice, engine revolutions should be reduced on entering the more open patches. If revolutions are maintained, the vessel will gather way as she passes through the clearer water, and her speed may become too great to re-enter the close pack ice safely.

Use of engines and rudders: The propeller(s) and rudder(s) are the most vulnerable part of any vessel, and particularly so in ice. Engines must be prepared to go full astern at any time, and should a vessel be required to go astern in ice, it should be done with extreme care, and always with the rudder amidships.

If a vessel is stopped by a very close concentration of pack ice, the rudder should be put amidships and the engines kept turning slowly ahead. This will wash the ice clear astern. Once checks of the propeller have been made, the vessel can come astern.

When a vessel is working in very close pack ice, floes submerged by the bow often pass under the vessel. If this occurs, speed should immediately be reduced to dead slow. thereby reducing the flow of water/ice into the propellers.

Violent rudder movements should only be used in an emergency, such as when beset, as they may cause the stern to swing heavily into ice, particularly when navigating in drift ice which comprises multi-year floes.

Effect of rudder use on speed: Frequent use of the rudder, especially in the hard-over position, can be employed both as a means of slowing the vessel's advance in drift ice, while maintaining the flow past the rudder, which would be lost with a reduction of propeller revolutions, and as a means of making the vessel roil in very close pack ice, reducing the static friction of ice against the ship's side, and helping to maintain advance.

Too much use of the rudder when pushing through pack ice, or when following an icebreaker, may bring the vessel to a complete stop.

Basic manoeuvring

When operating in ice, there are always four basic rules, regardless of ice type:

• Excessive speed leads to damage
• Once in the ice, keep moving, even if very slowly
• Work with ice movement, not against it
• Knowledge of ship's manoeuvring characteristics and turning radius is vital.

Impacts with ice are the greatest cause of vessel damage in polar waters. Because of the possibility of encountering much harder multi-year ice, massive heavy ridges or extremely hard glacial ice either alone or embedded within a lighter pack in polar regions, it is even more important to be aware of one's speed. The higher the speed, the greater the likelihood of serious damage.

This is no less the case when considering lateral impacts as opposed to bow impacts. Serious lateral damage can be experienced from ice thrown against a ship's hull by heavy seas when the vessel is transiting at speed. One should never underestimate the hardness of ice or that polar ice with possible multi-year or glacial ice inclusions may be harder than first-year or fresh water ice. Impacts at speed are dangerous.

A vessel stopped in ice for any length of time runs the risk of being frozen in and beset, or pinched as pressure builds around the vessel — therefore it is important to keep some way on if at all possible. The strategy is to prevent becoming beset. Once a vessel is stuck in the ice, it is at the whim of the movement of the ice and the risk of being run on to shoal ground increases.

In always working with the ice and not against it, the first plan is to avoid ice. A higher expenditure in fuel to proceed around or clear of ice where possible is likely to pay dividends. The alternative may in fact be greater fuel consumption working against the ice, or even costly voyage delays and stoppage. Do not work against the ice, the power of which considerably outrates the vessel's engine power. Use the pack and its movement to your advantage.

Knowing well the vessel's manoeuvring characteristics is vital when in ice. Often radical turns and rapid changes in speed may be required. It is important to know stopping distances to avoid collisions with ice, other vessels in convoy or icebreakers. When following leads and turning, knowing the centre of turn radius and how the aft structure rotates is necessary to reduce the likelihood of side impacts as the vessel turns to negotiate the maze of leads.

During any transit in ice, the bridge team has a greater part to play than in open water transits. As in entering any close navigation situation, the most experienced helmsman should be selected and given clear direction before entering the ice and latitude to act as necessary in conjunction with the OOW's overall navigational guidance. Often the helmsman is given a base course to maintain and some freedom to manoeuvre through the ice as conditions require. The helmsman should be given clear instructions to: 

• Put the rudder amidships immediately when astern movements are ordered until the vessel begins moving forward again or the 00W orders otherwise
• If an impact on an ice floe is imminent, ensure it will be on the bow with the stempost
• Avoid passing near heavy floes to decrease the possibility of impacts against ice on the side shell plate
• Avoid sharp turns in heavy ice
• Turn the rudder towards heavy ice to prevent the bow swinging inadvertently towards weaker ice and exposing the side shell to the heavier ice. 

Ship handling techniques in ice

Manoeuvres in Different Ice Conditions

Ice is an obstacle to any ship, even an icebreaker, and the inexperienced navigator is advised to develop a healthy respect for the potential strength of ice in all its forms. However, it is quite possible, and continues to be proven so, for well-maintained and well-equipped ships in capable hands to navigate successfully through ice-covered waters. Masters who are inexperienced in ice often find it useful to employ the services of an Ice Advisor for transiting the Gulf of St. Lawrence in winter or an Ice Navigator for voyages into the Arctic in the summer.

The first principle of successful ice navigation is to avoid stopping or becoming stuck in the ice. Once a ship becomes trapped, it goes wherever the ice goes. Ice navigation requires great patience and can be a tiring business, with or without icebreaker escort. The longer open water way around a difficult ice area whose limits are known is often the fastest and safest way to port or to reach the open sea.

NOTE: Do not underestimate the hardness of ice and its potential for inflicting damage.

Before Entering the Ice

For an unstrengthened ship, or for a ship whose structural capability does not match the prevailing ice conditions, it is preferable and safer to take any alternative open water route around the ice even if it is considerably longer. An open water route is always better than going through a large amount of ice. Any expected savings of fuel will be more than offset by the risk of damage, and the actual fuel consumption may be higher by going through ice, even if the distance is shorter.

The following conditions must be met before a vessel enters an ice field:

• Follow the route recommended by the Ice Superintendent via the Marine Communications and Traffic Services Centre (MCTS). This route is based on the latest available information and Masters are advised to adjust their course accordingly if changes are recommended during the passage.
• Extra lookouts must be posted and the bridge watch may be increased, depending on the visibility.
• There must be sufficient light to complete the transit of the ice field in daylight or the vessel must be equipped with sufficient high-powered and reliable searchlights for use after dark.
• Reduce speed to a minimum to receive the initial impact of the ice.
• The vessel should be at right angles to the edge of the pack ice at entry to avoid glancing blows and the point of entering the ice must be chosen carefully (see Figure 49), preferably in an area of lower ice concentration.

Correct Approach to Ice Field: Reduced Speed and Perpendicular to Edge

• The engine room personnel should be briefed fully as to the situation and what may be required of them, as it may be necessary to go full astern at any time, and engine manoeuvres will be frequent as speed is constantly adjusted.
• The ship should be ballasted down to ice draft, if appropriate, or to such a draft that would offer protection to a bulbous bow, rudder, or propeller (as applicable).
• The ship should be fitted with an internal cooling system for use in the event that the main engine cooling water intake becomes clogged with slush ice.

After Entering the Ice

Once the ice is entered, speed of the vessel should be increased slowly, according to the prevailing ice conditions and the vulnerability of the ship. If visibility decreases while the vessel is in the ice, speed should be reduced until the vessel can be stopped within the distance of visibility. If in doubt, the vessel must stop until the visibility improves. The potential of damage by ice increases with less visibility. If the vessel is stopped, the propeller(s) should be kept turning at low revolutions to prevent ice from building up around the stern.

When navigating in ice, the general rule is:

• Use the pack to its best advantage. Follow open water patches and lighter ice areas even if initially it involves large deviations of course.
• In limited visibility, beware following an open water lead at excessive speed, it may be the trail of an iceberg.

Do not allow the speed to increase to dangerous levels when in leads or open pools within an ice field, or when navigating open pack conditions.

Turning in Ice

Changes in course will be necessary when the vessel is in ice. If possible course changes should be carried out in an area of open water or in relatively light ice, as turning in ice requires substantially more power than turning in water, because the ship is trying to break ice with its length rather than with its bow, turns should be started early and make as wide an arc as possible to achieve the new heading. Care must be taken even when turning in an open water area, as it is easy to underestimate the swing of the ship and to make contact with ice on the ship's side or stern: a glancing blow with a soft piece of ice may result in the ship colliding with a harder piece.

The ship will have a strong tendency to follow the path of least resistance and turning out of a channel may be difficult or even impossible. Ships that are equipped with twin propellers should use them to assist in the turn. In very tight ice conditions, a ship sailing independently may make better progress by applying full power and leaving the rudder amidships. This allows her to find the least resistance without any drag from the rudder in trying to maintain a straight course by steering.

Warning: avoid turning in heavy ice – seek lighter ice or open water pools.

If it is not possible to turn in an open water area, the Master must decide what type of turning manoeuvre will be appropriate. If the turn does not have to be sharp then it will be better to maintain progress in ice with the helm over. When ice conditions are such that the vessel's progress is marginal, the effect of the drag of the rudder being turned may be sufficient to halt the vessel's progress completely. In this case, or if the vessel must make a sharp turn, the star manoeuvre will have to be performed. This manoeuvre is the equivalent of turning the ship short round in ice by backing and filling with the engine and rudder. Masters will have to weigh the dangers of backing in ice to accomplish the star manoeuvre, against any navigational dangers of a long turn in ice. Care must be taken while backing on each ram that the propeller and rudder are not forced into unbroken ice astern.

Danger in Turning in an Ice Channel

Backing in Ice

Backing in ice is a dangerous manoeuvre as it exposes the most vulnerable parts of the ship, the rudder and propeller, to the ice. It should only be attempted when absolutely necessary and in any case the ship should never ram astern. In recent years “double-acting” ice strengthened vessels have been developed which are designed to break ice while moving astern in order to protect their bulbous bows, but only this type of specially designed vessel should attempt such manoeuvres.

The ship should move at dead slow astern and the rudder must be amidships (Figure 51). If the rudder is off centre and it strikes a piece of ice going astern, the twisting force exerted on the rudder post will be much greater than if the rudder is centred. In the centre position, the rudder will be protected by an ice horn if fitted.

If ice starts to build up under the stern, a short burst of power ahead should be used to clear away the ice. Using this technique of backing up to the ice and using the burst ahead to clear the ice can be very effective, but a careful watch must be kept of the distance between the stern and the ice edge. If a good view of the stern is not possible from the bridge, post a reliable lookout aft with access to a radio or telephone.

Warning: avoid backing in ice whenever possible. If you must move astern, do so with extreme caution at dead slow.

Backing onto Ice: Rudder Amidships. Dead Slow Astern.

Entering ice

Before entering ice, it is always advisable first to determine that no alternative ice-free route exists, even if this may require additional fuel expenditure. Extra lookouts should be posted and the engine room watch advised if sea suction or other changes are required. The ship should have already been ballasted to ensure sufficient submersion of the propeller, rudder(s) and bulbous bow to avoid impact with ice and that the hull ice belt, if fitted, is at the water line. Refer to the ship's stability data for possible ice draught. 

Entering ice

Reduce speed to a minimum and manoeuvre the vessel to take the first impacts of ice directly on the bow with the vessel at right angles to the ice edge. If at all possible, select an area of least ice thickness or concentration. Open leads or breaks in the ice should be used. If ridging is apparent, it is a likely sign of ice under pressure and a more suitable entry point should be found.

If the vessel is approaching ice from downwind, generally ice will be open and entry will be favourable. However, as the vessel continues into the ice, concentration will increase. A vessel approaching ice from upwind will probably encounter a heavier concentration of ice at the ice edge and progress into the ice may be met initially with greater difficulty. It may be advisable to avoid entry into ice that is under pressure from wind and current and that may be thrown against the hull. 

In ice

Once in the ice, speed may be increased gradually - but not quickly or dramatically -taking into consideration the vessel itself and the prevailing ice conditions. Always consider speed in relation to visibility and reduce speed so that the vessel can clearly stop within the visibility distance available. Be aware that in polar ice regimes, harder multi-year ice, ridges or glacial ice may exist among what appears to be more benign first-year or rotten ice. 

Ice field with bergy bit in foreground and iceberg in background

Follow open water patches, leads, regions of lesser concentration and floes of less thickness. When deviating off planned tracks to take advantage of open leads and lesser ice concentration, always be aware of available depth relative to draught. Turns should be made when in open water areas or light ice if at all possible. Take care in estimating the swing of the stern, as lateral impacts in this area may result in serious damage to less ice-strengthened hull portions or to propellers and rudders. When turning in ice, gradual increase in power may be required as the flat sides of the vessel's hull may be breaking ice more than the bow. Be aware that glancing blows on ice may cause the vessel to swing or slide laterally into heavier ice.

Generally a vessel will tend to follow lighter ice, the path of least resistance, and the navigator should be aware that additional power may be required to turn as necessary. Abrupt increases in power should never be used. In more consolidated ice, a turning short round manoeuvre requiring judicious backing and filling to negotiate a turn may be required.

Always be aware of wind direction, and take note of the effect of wind on ice. While offshore winds will often open shore leads that can be taken advantage of, a change of wind to onshore may soon trap the vessel and drive it on to the lee shore. When choosing leads, always consider wind effect and the possibility that the lead may close or that ice may be under pressure. Ice closing behind a vessel as it proceeds indicates pressure.

Icebergs, because of their large draught, are predominantly affected by current whereas floating sea ice is predominantly affected by wind. Smaller glacial ice fragments, however, are generally wind-driven, similar to sea ice. As fragments break off the main iceberg they begin to come under the effect of the wind and proceed downwind like a debris field. As a result, the preferred course around an iceberg to avoid the smaller debris downwind, is upwind of the iceberg itself.

Turning in ice 

Never pass close to an iceberg as the underwater portion, which is the greatest mass of the structure, often extends well out from the visible portion above water.

As icebergs age and degrade, they become inherently unstable and subject to rapid roll-over. Ships have suffered severe structural damage passing close by an iceberg that subsequently turns turtle, striking the ship, or even from the waves generated by the roll heaving the ship unexpectedly.

Care must be taken at all times when backing ice to ensure that heavy ice is not thrust against rudders or propellers. The rudder should be centred during all astern movement. Short bursts ahead to clear ice from the stern are often advisable. When ice washing the stern clear of ice with ahead movements, cycling the rudder from port to starboard will widen the area astern cleared. 

If the vessel construction is suitable and entry into multi-year ice or passage through a ridge is necessary, the navigator should select a point of least pressure or thickness, first approaching dead slow to survey the entry point and come to a stop. Immediately use astern movements (verifying the stern is clear of ice) and back away a short distance. Repeat the approach at a slight angle from the original contact point and in repeated fashion use a herringbone sequence to impact the ridge alternately to port and starboard to widen the opening and weaken the ice. Unless the vessel is a purpose-built icebreaker, ramming should be avoided and it should certainly not be attempted by vessels constructed with bulbous bows.

Normally the vessel should avoid large floes, going around where at all possible. If two floes of similar age or thickness are joined, it is preferable to break on either side of the point where the two floes join, as this area is likely to be ridged and more difficult to negotiate. If two joined floes of different age or thickness are encountered, break through the younger or floe of thinner ice.

If an open lead exists between two floes, but is less than the breadth of the vessel, the lead may be widened by an initial breaking run into the floe to windward or with no wind on the younger or ice of lesser thickness.

When passing through areas of lesser concentration of ice between two areas of higher ice concentration, reduce power. This may seem counter-intuitive at first, but: power has probably been INCREASED to proceed through the higher concentration so when the vessel clears the ice and enters more open conditions, speed will invariably increase. It is important to enter the next ice field or floe at as slow a speed as possible and once within the ice again to increase power slowly to a level necessary to maintain way.

Use of ice imagery

Ice Observations

1. Aerial Ice Observations
2. Shipboard Ice Observations
3. Iceberg Observations
4. Ice Thickness Observations

1. Aerial Ice Observations

Using aircraft as platforms from which to conduct ice reconnaissance, a nearly synoptic description of ice conditions can be obtained. Large areas of ice can be covered in a relatively short time, using the latest state-of-the-art electronic aids combined with visual observations, where weather conditions and daylight make it possible to see the ice surface.

However the limitations must be realized. As the observing distance from the aircraft increases, it becomes progressively more difficult to detect changes in the ice surface. Therefore it is necessary to determine the visibility limit, which is the maximum distance from the aircraft at which the ISS can confidently identify and locate ice features. Under normal circumstances, the visibility limit should not exceed 15nm (25 km) on each side of the aircraft. Ice observations made in the early morning or late afternoon under sunny skies allow for much easier identification of surface features away from the aircraft. In an overcast situation with snow covered ice, a condition known as flat light will often exist. This condition eliminates shadows and causes ice-surface features to appear insignificant or even invisible. Observing limits will change as a function of altitude and the prevailing horizontal and vertical visibility.

In order to successfully perform ice reconnaissance duties, the ISS must be able to recognize, identify and record the different characteristics and features which distinguish one ice type from another. Training and experience in ice recognition allows the ISS to identify ice types, concentrations, floe sizes and significant surface features.

Aerial observing platforms are usually stable relative to their intended track, but ground speed varies considerably with wind. For this reason, the aircraft position should be plotted on the ice chart with a dot every few minutes.

In the conduct of aerial ice reconnaissance, the ISS employs standard techniques and procedures which are designed to provide the maximum amount of useful, quality-controlled information. Discussion with the participating air crew as to the extent of flight, general area of reconnaissance, close-tactical support requirements and other particulars are routine for each flight. Attendance at pre-flight weather briefings is also normal.

Use of Electronic Aids: The ISS has available on board the reconnaissance aircraft several useful electronic aids that can be combined, where appropriate, with visual observations. These aids may include an airborne imaging radar and an airborne radiation thermometer (ART).

Airborne Imaging Radar: An imaging radar is the most valuable ice-observing tool. It is presently the only operational source of mapped ice information when the surface becomes obscured by fog or cloud. An ISS who is fully familiar with the operation and the limitations of the radar system can effectively delineate ice edges and large leads, estimate the total ice concentrations and when used in combination with other sources of information, identify and distinguish many ice types. There are two types of imaging radars that are used for ice reconnaissance. The first type is the Side-Looking Airborne Radar (SLAR), which is a real-aperture system. It differs from most other airborne radars in that the antenna is rigidly fixed to the aircraft and the energy is directed towards either side of the aircraft ground track. Scanning of the area to either side of the ground track is accomplished by the movement of the aircraft in flight. The radar returns are then processed and converted into intensity-modulated traces on cathode ray tubes. This light is used to expose film thus producing a photo radar map of the ground. The signal is also digitized and processed by on-board computers and is transmitted to ships and ground stations in digital format. It then is relayed to the Canadian Ice Service and Canadian Coast Guard Ice Operation Centres.

Imagery may be acquired at 25, 50 or 100 km swath widths on both sides of the aircraft. Generally speaking, the 100 km swath is used when wide aerial coverage is desired. If more detail is needed or the width of a channel being imaged is narrow, a 50 km swath may be specified. Unless otherwise specified, the SLAR is operated at the 100 km swath.

The second type of airborne imaging radar is the Synthetic Aperture Radar (SAR). This radar forms an image by a different process. It uses a relatively short antenna to produce a wide beam. The image is built up by successive scans but the radar also makes use of the Doppler history of the surface being scanned as the aircraft moves forward. As the beam of the radar moves across the surface, changes in position are calculated and this information is used in creating the radar image. The effect is to synthesize a much longer antenna than is physically possible on the SLAR, achieving a constant resolution across the image. This factor, along with a finer resolution, distinguishes the SAR from the SLAR.

The radar image is mainly a function of the return microwave energy which is dependent on the radar system parameters and the surface characteristics. Through practice and experience, radar imagery can be interpreted by studying changes in texture, pattern and tone.

2. Shipboard Ice Observations

Shipboard ISS are a very important part of the ice-observation network. They provide very detailed ice observations, as well as report characteristics of the ice not collected by aerial reconnaissance methods such as snow depth, ice thickness and ice behaviour.

These detailed observations of the ice are used to make more accurate interpretations of aerial charts as well as for climatological studies. Therefore shipboard ISS should always record ice conditions to the maximum possible detail.

Ice information to be collected should include, but not be limited to:

• Concentration
• Behaviour of the ice (i.e. movement, developing or releasing pressure)
• Thickness
• Topography
• Ridge heights
• Ridges per linear mile
• Iceberg observations
• Depth and surface coverage of snow
• Water temperature
• Melt state

Whenever possible, the ISS should disembark from the ship to the ice surface in order to measure its thickness and snow depth and to estimate or measure ridge heights.

The shipboard perspective is similar to the far-range of the aerial perspective as the ice cover is viewed from an extreme angle; this, along with its slow speed, limits the geographic extent of a ship-based ice observation. The low angle perspective of a ship’s deck requires special attention to maintain ice observation accuracy. Whereas an aerial observation depends primarily on surface features to determine ice types, a shipboard ISS should normally use ice thickness.

3. Iceberg Observations

Iceberg observations are acquired in several different ways from the air and from the surface. The method of reporting iceberg observations is the same for both types. Iceberg observations from the air are collected by visual means as well as using airborne radar. This manual will briefly describe visual iceberg observations only.

Aerial iceberg observations are made by dedicated flights or as part of the collection of sea ice data. For dedicated iceberg flights, basic sea-ice boundaries and concentrations shall be recorded. Otherwise icebergs have a lower priority but should be reported whenever possible.

The principal objective of iceberg observations is to identify and report all icebergs that are present within the area covered. The ISS should set his/her observing limits to the extent that he/she can be certain that all icebergs have been reported with a high degree of confidence.

Visual priority flights shall not be undertaken unless visibility along 90% of the planned flight track is forecast to be 15 nm or more. The optimum altitude for visual observation is approximately 1500 feet.

4. Ice Thickness Observations

Ice thicknesses are measured routinely at selected shore stations, ranging from the Arctic to the Great Lakes. Occasional thickness measurements are obtained from icebreakers. All thickness observations are desirable and should be obtained where and when possible.

These measurements serve to help verify aerial and shipboard observations by providing the exact WMO thickness category at the point of measurement. This data can be used to compare estimates made in the same area at the same time or during future observations. It can also be used to predict future ice thicknesses.

Ice Information

To conduct a sea voyage safely and efficiently, a mariner must have a well-founded understanding of the operating environment. This is especially true for navigation in ice. It is the responsibility of all mariners to ensure that before entering ice-covered waters, adequate ice information is available to support the voyage from beginning to end.

The ways and means of acquiring ice information suitable for navigation vary from one source to another. Content and presentation formats also vary depending on the nature of the system used to acquire the raw data, and the degree of analysis or other form of enhancement which may be employed in generating the final product.

Many information sources are not normally or routinely available at sea, especially outside Canadian waters. In some cases prior arrangements may be necessary to receive particular products. The mariner is encouraged to consider carefully the required level of information, and to make appropriate arrangements for its delivery to the vessel.

Levels of Ice Information

It is possible to distinguish four levels of ice information, characterised by increasing detail and immediacy:

• Background;
• Synoptic (summary or general survey);
• Route specific; and
• Close range.

Background information is primarily historical in nature. It describes the natural variability in space and time of ice conditions for the region of intended operation. It may also describe the relationship of ice conditions to other climatological factors including winds, currents, and tides. It is applied very early in the strategic planning process, but it may also be useful at any time during the voyage.

At the synoptic level, ice conditions are defined for specific regions and time periods. The information may provide either current or forecast ice conditions but, in either case, it is not very detailed. As synoptic information is normally used days or even weeks before entering the ice, and because conditions are often dynamic, its greatest value is as a support tool for strategic planning.

Route-specific information provides a greater level of detail than synoptic information, usually for smaller areas. The detail provided may extend to the identification of individual floes and other features of the ice cover, and is most useful at the tactical planning stage.

Close-range information identifies the presence of individual hazards which lie within the immediate path of the ship. This level of information provides critical support during monitoring and execution of the tactical passage plan.

Environment Canada’s Canadian Ice Service (CIS), provides ice information and long-range forecasts to support marine activities. At the synoptic level, the Ice Operations Division of the CIS provides valuable strategic planning information through a series of plain language bulletins, warnings, and short-range forecasts for ice and iceberg conditions. These are broadcast live by marine radio, with a range of up to 320 kilometres. Broadcast frequencies and schedules are listed in the Canadian Coast Guard publication Radio Aids to Marine Navigation, issued seasonally. Taped bulletins are broadcast continuously from Canadian Coast Guard radio stations with an effective range of 60-80 kilometres. Alternatively, most of this information is available on the CIS website or by subscription through the CIS Client Service section.

The most important external source of information available to the ship is the broadcast of ice analysis charts by the CIS. For ships equipped with their own reconnaissance helicopter, aerial visual observations may provide considerably more ice information at the route planning and tactical levels.

Remote Sensing Systems

With special purpose receiving and processing equipment, ships may take advantage of airborne and satellite borne remote sensing systems for complementary synoptic level ice information.

The Canadian Ice Service operates two airborne imaging radar systems for ice reconnaissance, which are able to transmit raw data directly to the CCG Ice Operations Centres. The all-weather systems can penetrate dry snow cover to produce grey-tone images of the ice surface. The level of detail afforded by these systems depends on sensor resolution, which may vary between 25 and 400 metres. The resultant images therefore, are well suited to the tactical route planning process. The higher resolution data may be used in conjunction with visual observations and marine radar at the close range hazard detection level.

Many commercially available systems enable ships to receive direct transmission of weather satellite imagery which may be used to assess regional ice distribution. These systems are designed to receive the VHF (137 MHz) image transmission from various weather satellites via inexpensive personal computer software. Image resolution is in the range of 3 to 4 kilometres, providing suitable information for synoptic level voyage planning. The low cost of these systems (typically in the tens of thousands of dollars) makes them suitable for a larger number of ships transiting ice-covered waters.

Canada has a fully operational imaging radar satellite known as RADARSAT-2, which provides highresolution (100 metre) global coverage of ice-covered waters on a nearly continuous basis. RADARSAT-2 has the capability to send and receive data in both horizontal (H) and vertical (V) polarizations. Images acquired with the various combinations of polarizations on transmit and receive can be displayed on single channels or in various combinations including ratios and false colour composites.

Sea ice of Baffin

Ice in Scandinavia

Detachment of sea ice

Areas of ice floes

Areas of pack ice

Use of Radar for Ice detection

Radar can be a great asset in ice navigation during periods of limited visibility, but only if the display is properly interpreted. Ice makes a poor radar target beyond 3 to 4 nautical miles and the best working scale is in the 2 to 3 nautical mile range. Radar signal returns from all forms of ice (even icebergs) are much lower than from ship targets, because of the lower reflectivity of radar energy from ice, and especially snow, than from steel. Detection of ice targets with low or smooth profiles is even more difficult on the radar screen, although the radar information may be the deciding factor when attempting to identify the location of these targets under poor conditions, such as in high seas, fog, or in heavy snow return. For example, in close ice conditions the poor reflectivity and smooth surface of a floe may appear on the radar as a patch of open water, or signal returns from sea birds in a calm sea can give the appearance of ice floes. In an ice field, the edge of a smooth floe is prominent, whereas the edge of an area of open water is not. The navigator must be careful not to become over-confident in such conditions.

In strong winds the wave clutter in an area of open water will be distributed uniformly across the surface of the water, except for the calm area at the leeward edge.

Ice within one mile of, and attached to, the shore may appear on the radar display as part of the land itself. The operator should be able to differentiate between the two if the receiver gain is reduced. Mariners are advised not to rely solely on radar for the detection of icebergs because they may not appear as clearly defined targets. In particular, mariners should exercise prudence when navigating in the vicinity of ice or icebergs. The absence of sea clutter also may indicate that ice is present. Although ridges may show upwell on the radar display, it is difficult to differentiate between ridges, closed tracks of ships and rafted ice, as all have a similar appearance on radar.

The effectiveness of marine radar systems will vary with power and wavelength. The optimum settings for the radar will be different for navigating in ice than for open water. As the radar reflectivity of ice is much lower than for ships or land, the gain will have to be adjusted to detect ice properly. Generally, high-power radars are preferred and it has been found that radars with 50 kW output provide much better ice detection capability than 25 kW radars. Similarly, 3-centimetre radars (x-band) provide better ice detail while 10- centimetre radars (s-band) show the presence of ice and ridging at a greater distance - it is therefore recommended that both wavelengths be used.

 

Ice Navigation Radars

Conventional marine radars are designed for target detection and avoidance. Enhanced marine radars provide a higher definition image of the ice that the vessel is transiting through and may help the user to identify certain ice features. There are various shipboard marine radar systems enhanced and optimized for ice navigation. In the ice navigation radar, the analog signal from the x-band radar (azimuth, video, trigger) is converted by a modular radar interface and displayed as a 12-bit digital video image (1024x1024).

In the enhanced marine radar, the coastline is more clearly defined; icebergs are visible at greater distances, as are the smaller bergy bits and growlers. In the standard radar, sea clutter affects the ability to see smaller targets near the vessel. X-band radars will produce clearer images of the ice at short ranges, such as under 4 nautical miles, when set to a short pulse. The shapes of ice floes, the ridges and rafted ice and open water leads are also more distinct in an ice navigation radar, particularly when using the short radar pulse length.

Standard X-band Radar Image

Enhanced X-band Radar Image

Experiments with cross-polarized radar have demonstrated that it is possible to enhance radar displays for better detection of old and glacier ice. Advances are also being made in shipboard systems which use passive microwave radiometers to measure the natural emissivity of the ice (the relative ability of its surface to emit energy by radiation), producing radar-like displays which may be colour-enhanced to distinguish between open water and various ice types.

Icebergs

Icebergs normally have a high freeboard and, as such, they are easy to detect visually (in clear conditions) and by ship's radar. In poor to no visibility, radar must be relied upon. The radar return from an iceberg with low freeboard, smooth surface, or deep snow cover is less obvious, particularly if surrounded by bright returns from sea or ice clutter. Depending upon their size, aspect and attitude, icebergs may be detected at ranges between four and 15 nautical miles or even further for very large high profile icebergs, detection ranges diminishing in fog, rain, and other conditions affecting the attenuation of radar return. Icebergs may not appear as clearly defined targets but the sector of the radar display directly behind the iceberg may be free of clutter. Iceberg radar targets will sometimes cause a “radar shadow” on the far side, in which other targets will not show. It is sometimes possible to identify an iceberg target lost in the clutter by this shadow extending away from the observer. A large iceberg with a long and gently sloping aspect may not provide enough reflective surfaces to show at all on radar, so it should never be assumed that just because there are no targets in view there are no icebergs around.

 

Observation will reveal the shadow to increase in size on approach to the iceberg, and to swing around as the angle between the ship and the iceberg changes. However, care should be taken in using this technique as the returns from pack ice can obscure the return from the iceberg.

As the vessel gets closer to the iceberg, the size of the radar target reduces and may in fact disappear when very close to the iceberg, in which case only the shadow will remain to warn of the iceberg's presence. For this reason it is important to plot any iceberg (which has not been sighted visually) that the vessel may be approaching, until the point of nearest approach has passed.

Bergy Bits

From time to time pieces of ice break off, or calve, from an iceberg. The larger pieces are known as bergy bits, and the smaller pieces are known as growlers. Whereas the iceberg moves in a direction that is primarily the result of current because of its large keel area, the growlers and bergy bits are primarily wind driven, and will stream to leeward of the iceberg. While this is the general case, the effects of strong tidal currents may alter this pattern. However, for reason of the wind influence on bergy bits and growlers it is advisable, if possible, to move to windward of icebergs to avoid bergy bits and growlers. 

Passing distance from the iceberg is a function of the circumstances, but always bear in mind that:

• The closer the ship passes the more likely the encounter with bergy bits, and
• A very close pass should be avoided because the underwater portion of the iceberg can protrude some distance away from the visible edge of the iceberg at the sea surface.

The visual sighting of bergy bits depends on good visibility, and surrounding conditions of low sea state or fairly smooth sea ice. In windy conditions, the presence of bergy bits can be indicated by spray flung upwards by the waves striking the ice, while the ice itself remains invisible as the waves break over it. The differentiation of bergy bits (in waters where they are present) from open water or from a smooth first-year ice cover is relatively easy with radar, if the height of the bergy bit is sufficient for its return to be distinguished from the ice or water returns. The radar display should be checked carefully for radar shadows which may identify bergy bits with less height differential, or when the ice or water background is more cluttered.

Detection of bergy bits by radar is difficult in pack ice, especially if there is any rafting, ridging, or hummocks which cause backscatter and also may produce shadows that can obscure a bergy bit. Detection is particularly difficult if the surroundings are open pack ice, because radar shadows behind low bergy bits are small and are difficult to discriminate from the dark returns of open water between ice floes. As with icebergs, bergy bits should be avoided, but passing distances can be relatively closer, because the underwater portion of bergy bits is unlikely to extend as far to the side as for icebergs.

Growlers

Growlers, because of their low freeboard and smooth relief, are the most difficult form of glacial ice to detect (both visually and on radar) and, therefore, are the most hazardous form of ice. Very little of a growler appears above the water surface because of the low freeboard of the ice and waves may completely cover it. Unless recently calved, water erosion will have made the surface of a growler very smooth, making it a poor radar target. In open or bergy water with good weather conditions visual detection of growlers is possible at two or three nautical miles from the vessel. In rough weather and heavy swells, a growler may remain submerged through the passage of two or more swells passing over it, making detection by any method even more difficult. Detection (on radar or visually) can be as little as 0.5 nautical miles from the vessel, if at all. It is important to keep a constant check on radar settings, particularly the tuning control (on manually tuned radars), to ensure that the radar is operating at maximum efficiency. Varying the settings can be useful, but care must be taken to ensure that the radar is retuned after any adjustment. It sometimes helps to sight a growler visually then tune the radar for maximum return.

 

For a growler in an ice cover, it may be possible to detect it visually in clear conditions (because it is often transparent, green, or dark in appearance), but it is often not possible to discriminate it from surrounding ice clutter on marine radar. As the exact location of each growler cannot be identified for certain amongst ice floes, care must be taken to determine a safe speed through the ice-covered area when navigating by radar.

Old Ice Floes

Detection of old ice floes is primarily visual, because differentiation between first-year and old ice on marine radar is not possible. Travel through old ice can be reduced by using ice analysis charts to avoid areas of high concentrations of old-ice. However, mariners must watch for old ice even in areas where it is not identified on ice charts. Visual identification is possible up to one to two 2 nautical miles from the ship in good weather. Old ice can be distinguished from first-year ice by more rounded and weathered surface, light blue colour, higher freeboard, and a well-defined system of melt-water channels. Old ice is widely encountered in the Canadian Arctic, Baffin Bay, Davis and Hudson Straits, as well as the Foxe Basin, and is occasionally found in the Labrador Sea, off the north east coast of Newfoundland and on the Grand Banks. It is not a hazard in Cabot Strait, Gulf of St. Lawrence, Great Lakes, or the St. Lawrence River.

Danger of icing up

Sea spray icing is a serious hazard for marine operations in high latitude regions. Many ships and lives have been lost when ships sank, or became disabled, after the accretion of ice on decks and superstructures. Large amounts of ice can raise the center of mass on a ship enough to result in a catastrophic loss of stability. Capsizing, extreme rolling and/or pitching, and topside flooding can occur as a result of the loss of stability and extra weight from the ice burden. 

Ice accumulation may occur from three causes:

• Fog, including fog formed by evaporation from a relatively warm sea surface, combined with freezing conditions;
• Freezing drizzle, rain or wet snow.
• Spray or sea water breaking over the ship when the air temperature is below the freezing point of sea water (about -2° C).

Icing from fresh water

From fog, drizzle, rain or snow, the weight of it; which can accumulate on the rigging may increase to such an extent that it is liable to fall and endanger those on deck. Radio and radar failures due to icebergs on aerials or insulators may be experienced soon after it starts to accumulate. The amount of ice, however, is small compared with the amount; which accumulates in rough weather with low temperatures; when heavy seas break over a vessel.

Icing from Sea Water

when the air temperature is below the freezing point of sea water and the ship is in heavy seas, considerable amounts of water will freeze on to the superstructure and those parts of the hull; which are sufficiently above the waterline to escape being frequently washed by the sea. The amounts so frozen to surfaces exposed to the air will rapidly increase with falling air and sea temperatures; and have in extreme cases lead to the capsizing of vessels.

Nevertheless, the dangerous conditions are those; in which strong winds are experienced in combination with air temperatures of about -2°C or below; freezing rain or snowfall increases the hazard. The rapidity; with which iceberg accumulates increases progressively as the wind increases above force 6 and as the air temperature falls further below about -2°C. It also increases with decreasing sea temperatures.

The rate of accumulation also depends on other factors; such as the ship’s speed and course relative to the wind and waves, and the particular design of each vessel.

Precautions to avoid icing up

Superstructure Icing

Superstructure icing is a complicated process which depends upon meteorological conditions, condition of loading, and behaviour of the vessel in stormy weather, as well as on the size and location of the superstructure and rigging. The more common cause of ice formation is the deposit of water droplets on the vessel's structure. These droplets come from spray driven from wave crests and from ship-generated spray. Ice formation may also occur in conditions of snowfall, sea fog, (including Arctic sea smoke) a drastic fall in ambient temperature, and from the freezing of raindrops on contact with the vessel's structure. Ice formation may sometimes be caused or accentuated by water shipped on board and retained on deck.

Vessel icing is a function of the ship's course relative to the wind and seas and generally is most severe in the following areas: stem, bulwark and bulwark rail, windward side of the superstructure and deckhouses, hawse pipes, anchors, deck gear, forecastle deck and upper deck, freeing ports, containers, hatches, aerials, stays, shrouds, masts, spars, and associated rigging. It is important to maintain the anchor windlass free of ice so that the anchor may be dropped in case of emergency. Constant spray entering the hawse pipes may freeze solid inside the pipe, also anchors stowed in recessed pockets may freeze in place, both conditions preventing letting the anchor go. It is good practice in freezing spray to leave anchors slightly lowered in the hawse pipe in order to free them from ice accretion when needed. It is also advisable to maintain securing claws in place in case of slippery brakes, so that the anchors can be readily released in the event of a power blackout.

 

Severe Icing Conditions

Superstructure icing is possible whenever air temperatures are - 2.2°C or less and winds are 17 knots or more. It is very likely to take place when these conditions occur at the same time.

In fresh water such as the Great Lakes and St. Lawrence River superstructure icing will occur at 0°C and below, and accumulate faster than in salt water conditions.

Generally speaking, winds of Beaufort Force 5 may produce slight icing; winds of Force 7, moderate icing; and winds of above Force 8, severe icing.

Under these conditions, the most intensive ice formation takes place when wind and sea come from ahead. In beam and quartering winds, ice accumulates more quickly on the windward side of the vessel, thus leading to a constant list which is extremely dangerous as the deck-immersion point could easily be reached with a loaded vessel.

 

Ice being removed from the bulwark region

Ice build-up on forecastle

Options during icing up

The effects of freezing spray can be minimized by slowing down in heavy seas to reduce bow pounding, running with the sea, or seeking more sheltered sea conditions near-shore or in sea ice. Another option may be to head to warmer waters, although this is not possible in many Canadian marine areas.

Under severe icing conditions, manual removal of ice may be the only method of preventing a capsize. It is important for the Master to consider the predicted duration of an icing storm and the rate at which ice is accumulating on his vessel in determining which strategy to follow.

Several tips for minimizing icing hazards on fishing vessels are:

• Head for warmer water or a protected coastal area;
• Place all fishing gear, barrels, and deck gear below deck or fasten them to the deck as low as possible;
• Lower and fasten cargo booms;
• Cover deck machinery and boats;
• Fasten storm rails;
• Remove gratings from scuppers and move all objects which might prevent water drainage from the deck;
• Make the ship as watertight as possible;
• If the freeboard is high enough, fill all empty bottom tanks containing ballast piping with seawater; and
• Establish reliable two-way radio communication with either a shore station or another ship.

Freezing spray warnings are included in marine forecasts by Environment Canada. However, it is difficult to provide accurate icing forecasts as individual vessel characteristics have a significant effect on icing. Graphs assessing the rate of icing based on air temperature, wind speed, and sea-surface temperature can provide a guide to possible icing conditions, but should not be relied on to predict ice accumulation rates on a vessel. Caution should be exercised whenever gale-force winds are expected in combination with air temperatures below -2°C.

Winterization and preparedness of vessel

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Arctic Shipping Sea Routes

The promise of shorter sea routes across the north, potential fuel savings, and even reduced piracy risks are attractive to ship owners in the always competitive shipping markets. Several different Arctic sea routes have been considered as potential transit options. Distance savings compared with traditional blue-water trading routes, which make use of the Suez or Panama canals, can be as high as 35%.

• Northern Sea Route (NSR): The NSR stretches across the Russian Arctic linking Asian and European waters.
• Northern European markets: It typically is the first route to be ice free in the summer. Maritime traffic has started to develop along the NSR since the creation of the Northern Sea Route Administration (NSRA) in 2012.
• Northwest Passage (NWP): The NWP is a complex of channels through the Canadian Archipelago. A few trial transits of dry bulk cargo and cruise operations have been successfully carried out to date, but some projections estimate the NWP to become usable on a regular basis by 2020-2025.
• Arctic Bridge: The Arctic Bridge is a potential route that links the Port of Churchill in northern Manitoba, Canada with western parts of Russian and Scandinavia. The Port of Churchill is ice-free in the summer months and is served by a rail line extending to the Canadian national railway system.
• Transpolar Sea Route: The Transpolar Sea Route extends directly across the Arctic Ocean to link the Bering Strait with the North Atlantic. This route is currently hypothetical as it requires an essentially ice-free Arctic Ocean.

Typical passages through the Northern Sea Route

Polar shipping Routes

Northwest passage

Northeast passage

Winterisation

Before transiting the Northern Sea Route (NSR), companies should assess the ship's capability to operate in the anticipated ice and low temperature environment. Winterisation notations issued by Classification Societies are not the same as Ice Class notations. Ice Class notations refer to the ability to structurally withstand navigation through ice, whereas winterisation notations refer to the ability to operate within a low temperature environment. A company may choose to apply for a ship to have a winterisation notation but this may involve a considerable amount of retrofitting of equipment.

The following winterisation measures are recommended, even if a ship is only going to be used for a single transit of the NSR:

• Assurance of the proper operability of ship's equipment and systems in the anticipated low temperatures.
• The provision of equipment and supplies that are capable of being used in the anticipated low temperatures.
• The implementation of procedures for safe operation and personnel welfare in the anticipated low temperatures.

These measures are in addition to any hull and machinery requirements necessary for safe navigation through ice.

Winterisation checklist 

Before transiting the NSR, companies are encouraged to review their winterisation procedure and make sure the following are addressed in the winterisation checklist:

• Test of communications equipment.
• Test of deck lighting and projectors.
• Operational test of navigation equipment.
• Operational test of bridge windows heating and clearing systems.
• Operational test of horn and whistle heating system.
• Operational test of equipment heaters (in steering gear room, control equipment, electric motors, radar scanners, radar gear box).
• Lifeboat and davit readiness.
• Deck lines liable to freeze are drained dry.
• Sufficient amount of salt, sand and equipment to remove snow and ice is on board for the anticipated voyage.
• Firefighting equipment and life-saving appliances are protected from low temperatures. Potable water normally stored in the lifeboats should be removed and placed in a heated compartment close by unless the lifeboat interior is kept heated.
• Continuous steam supply is available on deck, while ensuring that any deadlegs are drained to prevent freezing.
• Ventilation to interior spaces has been reduced to prevent outside air from coming into direct contact with inside equipment.
• Switch to lower sea chest and operate steam injector if provided.
• When fitted, the Pressure Vacuum Breaker (PV Breaker) is checked for correct level of antifreeze and that steam is supplied to the deck water seal.
• Deck hydraulic systems free of water/moisture.

Regular checks should be carried out on all equipment exposed to low temperatures to make sure they are working properly and are safe.

Deck Equipment 

Deck Line 

1. Isolate and drain seawater and freshwater lines on deck to prevent freezing. 
2. Fire main drain status “open or close” to be posted in the ship’s office, wheelhouse, and engine control room. 
3. Post caution notices at local and remote starting points of various pumps whose lines have drain valves open. 
4. Install rubber hoses in exposed deck scupper pipes. 
5. Freshwater tanks heating to be on (where fitted). 

Fire Line 

Prior to arrival in a cold weather area, the fire line must be drained completely. After the draining, all exposed valves must be left cracked open because under cold weather conditions, the frozen moisture between seat, flap and stem may render valve opening impossible (lubricate stems).

Some fire line configurations will need additional drain valves fitted at the lowest point, where water could be completely drained. 

Using fire lines in below freezing temperatures requires a constant flow of water through all exposed lines and branches. This is achieved by opening end valves slightly, leading water overboard through hoses. 

After using the fire line, a quick draining of the line is necessary. To achieve quick draining (less than 10 minutes), the lowest valve on the main deck should be fully opened as well as upper exposed valves on the line (bridge deck and forecastle). The airflow in the line from the upper valve(s) will accelerate the line’s drainage due to venting action. 

After draining the line, all exposed valves must be left cracked opened except the valve for washing anchors, so as to avoid ice accumulation in the anchor hawse pipe and inadvertent pressure loss if a fire should occur. Secure shut isolating valves in forecastle.

Deck Equipment 

Cargo cranes are vulnerable under cold temperatures. Sluggish hydraulic control and slippery brakes are very common. Failure to overcome these difficulties has led to fatal accidents in the past. In order to overcome these problems, cranes should be warmed up and all safety switches tested, well in advance. Motor, pump and hydraulic oil heaters must be kept on, as cold conditions persist. 

1. All exposed electric and air motors of the following equipment is to be securely protected with canvas covers : accommodation ladders, provision cranes, bunker davits, electric whistle motor on the foremast and forward and aft winch starting switch boxes. 
2. Start motors and pumps of gangways, provision cranes, pilot doors and bow thruster well in advance of their use. If practicable, keep them running continuously, otherwise, perform idling runs at a suitable frequency, decided under prevailing conditions. The pilot doors’ trace-heating (where fitted) to be kept on at all times during the winter season. The pilot reels power to be always kept on so that space heaters remain on. Check the oil level in the pilot doors’ storage tanks. 
3. Start the windlass/mooring winches motors and pumps well in advance. In severe cold conditions, turn on hydraulic tank heaters, and if practicable, keep the pumps running and keep the winches turning at slow speed, otherwise, perform 30-minute idling runs every 5 to 6 hours. Duration and frequency, is to be carefully decided under prevailing conditions. Also, check the oil level in the hydraulic tanks for the forward and aft winches before putting into use. A thermostat should control the hydraulic tank heaters automatically. 
4. Ensure all mooring-ropes on the drums are kept securely covered with strong canvas covers. 
5. Windlass, compression-bar on the bow-stoppers, mooring-winches, cargo-winches, open gears, engaging clutches, pins, operating handles, brake clamping bolt threads - all to be liberally covered with grease. All nipple points to be greased up. 
6. All loose lashing material on deck to be stowed away in bins and stowage racks, as far as practicable. 
7. All lashing material in use (turn-buckles, shackles etc.) to be liberally greased. 
8. Do not use manila ropes for any lashings on deck, as it becomes stiff and impossible to handle. Polypropylene and some other synthetic ropes are best suited for severe temperature use. 
9. All exposed movable parts (butterfly nuts/bolts, flap hinges, vents, valve spindles, sounding pipe covers, hydrant wheel spindles, steel door dogs, etc.) to be kept liberally covered with grease. Some antifreeze mixed into the grease is very effective. 
10. Pilot doors’ wheels and rams, pilot ladder rollers and track ways to be well greased. 
11. Regularly clear decks and walkways between hatches, of snow and ice. 
12. Keep shovels, crow bars, hammers, spikes, sledge hammers, pickaxes (fire-axes will suffice), grease-pot, blow-lamp and sufficient salt, handy and in convenient sheltered locations near work areas. 
13. When receiving freshwater alongside, water is to be left running continuously. Ensure that the end of the hose is pushed well down inside the freshwater tank filling pipe to prevent freezing. 
14. Ensure heating (where fitted), are kept in operation in storage room. 
15. Hold bilges, store bilges, chain lockers and the bilges for the side passage ways to be stripped dry. 
16. Use heaving line (rubber hose) or environmentally safe antifreeze in sounding pipes in order to prevent bursting of pipes. 

Pilot Transfer Procedures 

1. The pilot ladders should be kept in a protected area and covered to prevent ice accumulation; it should be deployed at the last moment and stored again between pilot stations. The pilot ladder, the accommodation ladder, its platform and all the stanchions in use must be examined and free of ice before being deployed. It should be protected and stored between pilot stations in order to avoid the effect of freezing spray and ice accumulation caused by the sea smoke clinging and freezing on the ropes and steps. 
2. Minimize the vertical climb on the pilot ladder. If the vessel is equipped with an arrangement to provide a combination of pilot ladder and accommodation ladder that meets the regulations, we strongly suggest that it should be deployed regardless of the freeboard. Winter boots and extra clothing make climbing of a pilot ladder even more perilous during the winter season. Deploying the combination ladder will minimize the vertical climb and mitigate the risk of a fall. Special care should be given to the importance of protection by handrails and taut ropes on the boarding platform. The platform must be in a horizontal position. The use of salt or other de-icing products on the stairs, steps and boarding area will contribute to an “ice-free” boarding environment. 
3. Check all mechanical equipment used in transfer procedures. Winches, controls and power source (air, hydraulic) should be tested in advance to ensure their proper operation in cold climates. 
4. Ensure safe access on deck. Ice and snow should be removed from the vicinity of the affected personnel the pilot boarding area. 
5. Ship personnel should wear proper winter clothing. It may take longer for the pilot boat to come alongside the vessel due to prevailing weather and/or ice conditions. 
6. Bridge/Deck communications should be tested. The officer supervising the transfer procedures should verify the charge of the VHF batteries prior to use as cold weather has a detrimental effect on battery charge. 
7. Keep close supervision at all times during the pilot transfer procedures. The risks of a fall and its implications are far greater in winter; keep a watchful eye at all times. 
8. The arrangements and procedures should be adjusted to the freeboard of the pilot boat used at the pilot stations. At Les Escoumins and Trois-Rivières, the pilot boat has a freeboard of 1,5 m to 2 m. At Quebec City, the pilots are boarding from tugs that have a boarding platform located 5 m from the water with an alternate boarding station 3 m from the water. 

Navigation Bridge 

All ships should be fitted with a suitable means to de-ice sufficient conning position windows to provide unimpaired forward and astern vision. 

Humidity in the air from the heating system should be avoided in order to prevent window fogging and icing. 

The windows referred to above, should be fitted with an efficient means of clearing melted ice, freezing rain, snow mist and sea spray from the outside and accumulated condensation from the inside. A mechanical means to clear moisture from the outside face of a window should have operating mechanisms protected from freezing or ice accumulation that could impair effective operation. 

Restricted Visibility

Efficient lookout is the single most important aspect of navigation whether visibility is restricted or not. The OOW should visit the chartroom for the minimum time possible and he must always ensure that it is safe to do so each time.

During restricted visibility, extra care should be taken that there is a look out person available continuously. A vessel or a floating object can often show up at short range and there will be very little time to take action.

The biggest mistake an OOW can do in restricted visibility is to watch the radar screen continuously for targets. Remember that not all objects are detected by the radar effectively. 

A continuous 360 degree lookout is a must by sight and hearing. A sufficient number of lookout persons are is to be strategically placed to ensure the above. A lookout on the forward mast in direct communication with the wheelhouse is preferred. 

The lookout should be able to report at once any sound signals heard along with the bearing with reasonable accuracy. The fog horn on own ship should be operated either automatic or manually to sound the appropriate signal as required by the collision regulations.

The OOW has to check the following when in or nearing an area of restricted visibility:

1. The condition of visibility should be reported to the Master.
2. Call for additional lookouts and instruct them.
3. Inform the engine room as advised by Master.
4. Set the radar and ARPA to optimum settings for prevailing conditions.
5. Select a suitable range and make full use of both the X-band and the S-band radars.
6. Consider changing over to manual steering depending on traffic around the vessel.
7. Visually confirm the navigation lights are on.
8. Proceed at a safe speed as advised by the Master.
9. Appropriate sound signals should be on.
10. Strictly follow Rule 19 – Conduct in Restricted Visibility of COLREG. 
11. Follow the Master’s standing orders and company procedures.

The sound reception system can be very useful but should not be used as a replacement for lookout.

Passage Planning in Restricted Waters 

By comparison with open waters, margins of safety in restricted waters can be critical, as the time available to take corrective action is likely to be limited. 

The manoeuvring characteristics of the ship and any limitations or peculiarities that the ship may have, including reliability problems with its propulsion and steering systems, may influence the route selected through coastal waters. In shallow water particularly, allowance should be made for reduced underkeel clearance caused by ship squat, which increases with ship speed.

Ships' routeing schemes, restricted areas and reporting systems along the route, as well as vessel traffic services, should be taken into account.

Coastal weather bulletins, including gale warnings, and coastal navigational warnings broadcast by coast radio stations and NAVTEX may require changes to be made to the route plan. 

Navigation in coastal waters

Have the following factors been taken into consideration in preparing the passage plan?

• Advice/recommendations in Sailing Directions
• Ship’s draught in relation to available water depths 
• Effect of squat on underkeel clearance in shallow water
• Tides and currents
• Weather, particularly in areas prone to poor visibility
• Available navigational aids and their accuracy 
• Position-fixing methods to be used
• Daylight/night-time passing of danger points
• Traffic likely to be encountered – flow, type, volume
• Any requirements for traffic separation/routeing schemes
• Ship security considerations regarding piracy or armed attack
• Are local/coastal warming broadcasts being monitored?
• Is participation in area reporting systems recommended including VTS?
• Is the ship’s position being fixed at regular intervals?

Has equipment been regularly checked/tested, including:

• Gyro/magnetic compass errors
• Manual steering before entering coastal waters if automatic steering has been engaged for a prolonged period
• Rader performance and radar heading line marker alignment 
• Echo sounder
• Is the OOW prepared to use the engines and call a look-out or a helmsman to the bridge?
• Have all measures been taken to protect the environment from pollution by the ship and to company with applicable pollution regulations?

1. Ensure individual heating to bridge windows remain on at all times (where fitted), when temperatures are below freezing. Drastic changes in temperatures created by a chill factor, may cause the glass to crack, due to thermal shock. 
2. Individual heaters in the wheelhouse to be kept on during winter (where fitted). If not fitted, at least two portable heaters (5000 watts each, with ventilator) should be safely and adequately installed, temporarily. 
3. Every effort shall be taken to prevent exterior windows from ice accretion. 
4. Drain the bridge window washwater line and leave drains open or use -45° C antifreeze window wash. 
5. Ensure whistle and horn heater remain on at all times. Ensure compressed air is moisture free. 
6. Slack down all signal halyards. 
7. Radar scanners to be kept running at all times. 
8. Special attention should be taken to avoid freezing of navigation and deck lights. 
9. Switches for the duct heaters to be switched on (where fitted). 
10. Clear-view screens to be kept running when needed. 
11. A container of coarse salt to be kept readily at hand in the wheelhouse especially in pilotage waters to prevent slipping accidents. 
12. Search lights, port and starboard, to be functional. 
13. Ensure trace-heating to EPIRB is on. It comes on automatically by thermostatic control as the temperature drops below –2^o C. 
14. Engine control air should be free of moisture. Line passage through cable trunk should be protected from freezing. 

Traffic Separation Schemes

There have been a number of major collisions in the TSS. One of those was the infamous collision between MSC Alexandra and the Dream II in Singapore Strait.

Container carrier MSC Alexandra and VLCC Dream collided in Singapore Strait. The very large crude carrier Dream collided with container ship MSC Alexandra in Singapore Strait on 2 nautical miles southeast off Sebarok island. The both vessels were proceeding on crossing routes, as the tanker was proceeding through the separation scheme in western direction, while the container ship MSC Alexandra was entering into the scheme from Singapore. The collision happened due to serious violation of the ColReg rules for vessels running on crossing routes. Following the collision, the crude carrier Dream suffered serious damages of the bow, while the container ship MSC Alexandra suffered damages in the port board. Also a dozen of empty containers fell overboard from the deck of MSC Alexandra. Fortunately there is no report about injuries and water pollution.

The local authorities started investigation for the root cause of the accident. According to preliminary information, responsible for the collision was the duty officer of very large crude carrier Dream, who was neglecting the ColReg rules, as container ship MSC Alexandra was proceeding from the right board and have to be released by the tanker to enter in the separation scheme. On other side, the lack of communication and misunderstanding from the both duty officers was in the root cause of the collision.

Colreg Rule 10 - Traffic separation schemes

     

(a) This Rule applies to traffic separation schemes adopted by the Organization and does not relieve any vessel of her obligation under any other Rule. 

(b) A vessel using a traffic separation scheme shall:

1. Proceed in the appropriate traffic lane in the general direction of traffic flow for that lane;
2. So far as practicable keep clear of a traffic separation line or separation zone;
3. Normally join or leave a traffic lane at the termination of the lane, but when joining or leaving from either side shall do so at as small an angle to the general direction of traffic flow as practicable.

(c) A vessel shall, so far as practicable, avoid crossing traffic lanes but if obliged to do so shall cross on a heading as nearly as practicable at right angles to the general direction of traffic flow.

(d) 1. A vessel shall not use all inshore traffic zone when she can safely use the appropriate traffic lane within the adjacent traffic separation scheme.  However, vessels of less than 65.62 ft in length, sailing vessels and vessels engaged in fishing may use tile inshore traffic zone.

2. Notwithstanding subparagraph (d)(1), a vessel may use an inshore traffic zone when en route to or from a port, offshore installation or structure, pilot station or any other place situated within the inshore traffic zone, or to avoid immediate danger.

(e) A vessel other than a crossing vessel or a vessel joining or leaving a lane shall not normally enter a separation zone or cross a separation line except:

1. In cases of emergency to avoid immediate danger,
2. To engage in fishing within a separation zone.

(f) A vessel navigating in areas near the terminations of traffic separation schemes shall do so with particular caution. 

(g) A vessel shall so far as practicable avoid anchoring in a traffic separation scheme or in areas near its terminations.

(h) A vessel not using a traffic separation scheme shall avoid it by as wide a margin as is practicable.

(i) A vessel engaged in fishing shall not impede the passage of any vessel following a traffic lane.

(j) A vessel of less than 65.62 ft in length or a sailing vessel shall not impede the safe passage of a power driven vessel following a traffic lane.

(k) A vessel restricted in her ability to manouevre when engaged in an operation for the maintenance of navigation in a traffic separation scheme is exempted from complying with this rule in the extent necessary to carry out the operation.

(l) A vessel restricted in her ability to manouevre when engaged in an operation for the laying, servicing or picking up of a submarine cable, within a traffic separation scheme, is exempted from complying with this rule to the extent necessary to carry out the operation.

The media below explains Traffic Separation Schemes:

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The Rule 10 of COLREGS does not override other rules. This means that a vessel when it is in TSS shall obey other rules as well as the rules within the TSS.

It gives suggestions on how a vessel should move in a traffic separation scheme. The correct traffic lane has to be followed at all times.

The courses should not be laid such that they get very close to the edges. It is preferred to draw them to as centre as possible.

A vessel should not abruptly come out of the TSS just like that. It has to join or leave the TSS in as small angle as possible.

The inshore traffic zone has to be used by smaller vessels less than 65.62 ft, including sailing vessels and fishing vessels. The big ships may have to use the inshore traffic zone when approaching a port or a pilot station or when loading or discharging cargo at a Single Buoy Mooring etc.

The ship should be very careful and take all precautions when coming out of ports, terminals or pilot stations. It is better to have extra lookouts and keep both radars on. Engines must be on standby and all emergency measures should be in place.

Vessels should not anchor in a TSS, but in emergencies it is allowed to. Sailing vessels and fishing vessels should steer clear of a TSS. Vessels when they are engaged in repairing work of a buoy or other maintenance in the TSS then they are not required to follow the rules of a TSS. The other vessels should observe this and keep well clear.

Joining and Leaving a TSS 

If we have to use a Traffic Separation Scheme, the first thing we have to do is to join that TSS.

But there are few mistakes that seafarers make while joining a TSS.

As per Rule 10 of the Colregs 

Normally join or leave a traffic lane at the termination of the lane, but when joining or leaving from either side shall do so at as small an angle to the general direction of traffic flow as practicable

This means that we must join the TSS at or before the point where it starts.

But the mistake is this.

Do you see any issue with this course in and around TSS?

The ship has planned to enter and leave the TSS at the termination of the TSS as required by rule no 10. 

Everything looks OK but there is one issue with this course.

The issue is that the ship has planned the to exit the TSS at a course that would trouble the ships about to join the TSS.

The solution to this issue is

Do not plan to alter the course towards the traffic planning to join the TSS. We can plan to continue to move on our course for a couple of miles and then alter the course.

In fact, this is exactly what rule 10(f) emphasizes on.

Crossing the TSS 

TSS makes it easy to navigate in congested waters. But that is not true if you need to cross a TSS.

Try crossing the TSS to pick up the pilot at Singapore.

The part of the TSS where there is expected crossing traffic is marked by a precautionary area.

Consider that your ship is arriving from the west and need to pick up the pilot at “Western pilot boarding A”. You need to cross the TSS to pick up the pilot.

Now the mistake is to plan the crossing this TSS like this.

This course may have the advantage of easily arriving at the pilot station with heading 090 (parallel to the breakwater).

But we must understand that we cannot cross the TSS at this angle.

As per the Rule 10,

A vessel shall, so far as practicable, avoid crossing traffic lanes but if obliged to do so shall cross on a heading as nearly as practicable at right angles to the general direction of traffic flow

Using a Wrong TSS 

There have been cases where where the port authorities fined the ship for using a wrong TSS.

What is meant by the wrong TSS?

At few places, you will find two Traffic separation schemes at the same place. That is two TSS in an upward direction and two in the downward direction.

Which TSS do we need to follow?

We just need to check the information on the chart and/or sailing directions for that area. This will have the information about each of these TSS.

The information could be something like this.

So if the ship is carrying dangerous cargo in bulk, the ship must use the lane C if southbound, and lane D if northbound.

Then this mistake?

While sometimes it may be just because of negligence, other times there may be other reasons.

The reasons like following the previously used passage plan. When the last time this TSS was used, the vessel may be loaded with dangerous cargo in bulk.

The next time, the vessel may not have dangerous cargo in bulk. But as the previous passage plan was used, vessel followed the wrong lane.

But whatever the reason, it cannot be an excuse for using the wrong lane.

Missing Mandatory Reporting

Using some of the TSS require the ships to do certain reporting. For some, the reporting is required just before joining a lane and on the VHF.

For others, it may be required a couple of days before entry into the TSS and through the email.

Not Acting Proactively in TSS 

While a navigator needs to be proactive in every aspect of navigation, navigating in TSS is particularly the area where this trait is very useful.

Let us see it with examples.

Is there anything wrong with this course in the Singapore TSS?

While there is nothing wrong with the course per se but the OOW (or Master) of this vessel may have a tough time crossing this area.

Because there would be a lot of traffic leaving the anchorage area and joining the opposite traffic lane.

With this course, we are creating a situation where some of this traffic might be crossing our bow.

This would be apart from the usual traffic that will be crossing the TSS for picking up the pilot.

A similar case is when you have to cross the Singapore TSS for picking up the pilot. If you plan your course like this, you are inviting trouble in crossing the TSS.

Because you will find it hard to alter your course to cross the TSS because of usual traffic in the TSS.

Then, what if we plan our course like this?

Surely, we are avoiding a lot of cross traffic this way.

We need to be proactive in planning our passage in the TSS.

Not Keeping the Vessel TSS Ready

Your company’s SMS manuals may or may not specifically mention this. But there are certain rules in navigating a vessel in the TSS, especially a congested TSS areas.

These rules are

• Keeping an extra A/E (generator) running, and
• Proceeding at a safe speed

Keeping an extra A/E (generator) running

When the ship is navigating in the TSS, there are a lot of vessels around own vessel at a comparatively shorter distance.

Most of these vessels are on a parallel course to the own vessel.

But should anything go wrong with any one vessel, we may need to alter our course quickly. This may require us to use the rudder hard over.

If the extra A/E is not running, the vessel may experience black out just when it requires the power most.

Proceeding at a safe speed

Sudden alteration of course may be required in the TSS but sometimes that is not the most effective action in the TSS. This may be because of dense traffic around, the width of the TSS or wrecks and other dangers around.

This will be the time when reducing (and sometimes increasing) the speed may be the most effective action.

But what if you are proceeding at the sea speed and need to give notice to the engine room (say 30 minutes notice) for reducing the speed?

In the open sea, alteration of course may be the best way to avoid the collision. But in TSS, it may sometimes be the reduction in speed.

Proceeding at full sea speed in the TSS will not be the safe speed.

Misunderstanding the Rule no 10 

TSS situations

• A vessel crossing own vessel from starboard (or port) side in TSS with the risk of collision. Who is give way vessel and what action do we need to take?
• A fishing vessel crossing own vessel in TSS. Who is give way vessel?
• A NUC vessel overtaking own vessel in TSS. Who is the give way vessel?

And these situations cannot be covered under a single answer.

A traffic separation lane does not give any right of way to any vessel over any other vessel.

This means that you should treat all TSS situations as if the same situation was in the open sea.

So action in case of crossing situation in TSS will be same as a crossing situation outside TSS.

Similarly, the action for the overtaking situation in TSS will be same as any overtaking situation outside TSS.

Not Following General Traffic Flow 

We plan the passage in the TSS that is not following the general traffic flow.

We all know why this is done purposely.

To avoid one extra line or course.

But we must understand that this is wrong and not as per rule 10 which states that

A vessel using a traffic separation scheme shall proceed in the appropriate traffic lane in the general direction of traffic flow for that lane

It may take us a couple of more lines to draw, but ideally, we must bend our courses parallel to the TSS.

Like this, for Strait of Hormuz.

Vessel Traffic Service (VTS) Areas

Vessel Traffic Service (VTS) is a system operating from the shore side that can range from simple collection of information messages from ships and providing information on traffic, weather warnings to extensive traffic management within a sea area or a port or a waterway. 

A ship when entering into an area governed by a VTS is obligated to report to the concerned authority usually by VHF radio. The VTS then may track the vessel’s position on their radar ashore.

The VTS will have a working frequency on the radio and the ship’s officer must keep a watch on this frequency as long as navigating within the area covered by the VTS or until the VTS operator advises otherwise.

Important navigational information or other warnings may be communicated to the ship via this frequency. The VTS operator will directly contact the ship if a traffic situation is developing or if a vessel is running towards danger.

The SOLAS convention makes way for the governments to establish and operate VTS if it is felt necessary considering the density of traffic and degree of risk.

The navigator must be aware of such VTS along the passage. It should be pre-planned and implemented in the passage plan. The Admiralty List of Radio Signals (ALRS) provides information on VTS which should be consulted when preparing passage plan.

The reporting points are marked on the chart before transiting the area. All information that needs to be communicated during the reporting are compiled and kept ready. The working frequency of the VTS is tuned on the radio and the station is called. 

It is important to keep a record of the reporting including the time of report and the information exchanged in the log book.

Area of Extensive Tidal Effects

Location	Country	Tidal Range (feet)
The Bay of Fundy	Canada	38.4
Ungava Bay, Quebec	Canada	32.0
Avonmouth / River Severn	England	31.5
Cook Inlet, Alaska	USA	30.3
Rio Gallegos (Reduccion Beacon)	Argentina	29.0
Hudson Bay	Greenland	28.5
Granville	France	28.2
Banco Direccion, Magellan Strait	Chile	28.0
Cancale	France	27.8
Iles Chausey	France	26.9