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While the vessel is in the discharge port the master should receive the orders for the next voyage. It is his duty to plan the route for the voyage to the next loading port in accordance with the requirements of the owner, the charterer and good seamanship. The basic requirements are safety, efficiency and economy. The main objective is safety of the crew, vessel and cargo. The ship must be provided with the latest navigation chart editions, corrected to the date of the latest notice to mariners on board. Radio navigation warnings must be reviewed to verify that the proposed route does not encounter any temporary hazard. The plan should be prepared using an owner approved checklist, indicating all information sources to be reviewed to properly complete the plan.

2.7.1 Owner's voyage instructions
The primary guidance for voyage planning are the guidelines set down by the vessel's owners. The owners should require strict compliance with the Convention on the international regulations for preventing collisions at sea, exclusion and separation zones and established policies for under-keel clearance, distances navigation hazards are to be passed, etc. They may also indicate how the voyage track is to be marked on the charts and how it should be verified.
Normally the voyage track will be drawn on the voyage charts by the master or ship's navigator and verified independently by the master or a second officer. Each leg of the voyage track must be measured to determine its length in nautical miles and the true course. A written voyage plan is prepared while courses are being laid down on the chart. The voyage plan should indicate:

  • The watch conditions expected to be set at each leg of the voyage.

  • Frequency of position fixing and navigation aids to be used. Where/when the master is to be called.

  • Seasonal considerations and weather routing.

  • Minimum distance(s) off for passing navigation hazards.
  • Passage plans for restricted waters are particularly important as these are the most difficult and dangerous parts of the voyage. All officers should review the plan during preparation and be fully aware of its details.
    The true course of each track segment must be marked on the chart. On some ships, the sounding line representing the shallowest navigable water for the ship is coloured in with red ink, as are all submerged hazards in deeper water. Owner's instructions regarding navigation in ice and use of weather routing services must be followed unless they conflict with the charterer's instructions, in which case the owner must be advised requesting clarification. In any case where the master is in doubt about the voyage orders, or believes that a more efficient or safe voyage plan could be used, he is required to proceed on the safest course while advising the charterer and requesting clarification.
    Owners will indicate if master is to participate in the automated merchant vessel reporting (AMVER), system operated by the US Coast Guard.

    2.7.2 Charterer's voyage instructions
    The voyage objective of the charterer is to get the vessel to the next port as rapidly as possible. Intelligent charterers will issue voyage planning instructions which place safety foremost, but they will also expect the maximum of efficiency and economy within those guidelines. Charterers expect the ship to be adequately provided with charts, publications and the latest navigation notices and warnings. Traffic separation schemes and ice navigation, speed, ballast, reserve bunkers, and water and timing of arrivals are usually discussed in charterer's instructions. Any navigation decisions which have a commercial impact should be communicated to the owner and charterer to avoid later claims for deviation or lack of adequate speed performance.
    Charterers will indicate to the master, as necessary, the ship's drafts for entering or leaving the ports. Drafts will always refer to seawater of specific gravity 1.025 unless indicated otherwise. The master must satisfy himself that the indicated loading or arrival draft is correct for the circumstances by reviewing the latest harbour and berth depth information available to him.

    2.7.3 Safe depth
    A safe depth is one which provides adequate under-keel clearance. To properly evaluate the safety of any track line which enters shallow water the master must consider:

  • The chart datum.

  • The stage of the tide while transiting.

  • Effects of the weather on water levels.

  • The actual draft of his ship allowing for trim 'squat' and list.

  • The accuracy of the chart surveys.

  • Failure to account for these effects can produce an under-keel clearance much less than that obtained by simple subtraction of the draft from the charted depth.
    Squat in shallow water can be calculated by the formula:
    SQUAT = (2 x Cb x Vs^2) = centimetres       Cb - block coefficient        Vs - speed in knots

    The most important part of this equation is the squared variable -speed. The effect of speed is apparent when a fully loaded 270,000 DWT VLCC proceeding at eight knots in shallow water will squat 1.1 meter, while at thirteen knots in shallow water the same ship squats nearly three meters! The effect is magnified further in dredged channels, adding more than a meter to the draft of a 270,000 DWT very large crude carrierVLCC travelling at six knots in a narrow channel. This is in addition to the shallow water depth squat increase.

    Squat is only one of the variables which determine underkecl clearance.

    It is clearly important to provide a large extra margin of under-keel clearance for those shallow areas which the master intends to pass at full speed. Where under-keel clearance is less than three meters the master should:

    a Reduce speed to the minimum necessary to provide steerage.
    b Increase steering ability when turning by putting the rudder over first then'kick' to the rudder with short bursts of higher engine speeds.
    c When under pilotage, discuss speed and squat with the pilot and agree on a maximum safe speed for the transit. Remember that the pilot is only an advisor. If the master believes that a slower speed should be used than that recommended by the pilot, then the master's view shall prevail.

    If excessive vibration is experienced while transiting shallow water, then the vessel's speed should be immediately reduced to minimise squat and increase the under-keel clearance.
    Vessel list increases the vessel's effective draft. For a ship with a 40 meter beam, each degree of list increases the effective draft amidship by 35 centimetres. A three degree list would increase this ship's draft by more than one meter. Where draft is critical, the ship should be placed on an even keel before proceeding.
    The heeling effect produced by the rudder when making a turn must be considered and the speed of the ship adjusted when approaching turns to minimise rudder induced list.
    Shallow water increases the turning circle of all ships. The turning diameter of a deeply laden VLCC will be doubled in conditions of restricted under-keel clearance. Deep draft vessels should avoid meeting other ships at turns or bends in shallow channels.
    Vessel turning behaviour in shallow channels requires that the master/pilot always indicate the amount of counter rudder required to check the swing of the ship. Never leave the amount of counter rudder to the quartermaster's discretion in shallow waters. If the vessel is proceeding at moderate (half), speed in shallow water, additional engine revolutions can always be called for to increase rudder force. This cannot be done if the ship is already at full speed.
    Proceeding in shallow channels with minimum under-keel clearance will reduce the speed of the ship, in some cases by 2/3!
    Deep draft vessels navigating in shallow channels should not overtake other vessels.
    Deep draft vessels navigating in narrow channels should display the 'constrained by draught' signal as appropriate.

    2.7.4 Separation schemes
    The provisions of the international rules concerning compliance with published traffic separation schemes must be followed when preparing a voyage plan.
    Where there are established major shipping routes, such as in the North Atlantic, the voyage should be planned to follow these routes, or at least laid down in such a way that the track does not conflict with the route recommended for vessels proceeding the opposite way.
    The IMO publication Ship routing and other national voyage planning guides summarise the internationally accepted ship routing schemes.

    2.7.5 Weather routing
    Weather routing services have as their objective indicating the 'least time route' for the ship. The distance recommended may be greater, however the time spent in adverse weather will be less. That advantage usually means that the ship arrives earlier than it would if it had fought its way through adverse weather on the shortest great circle track. The charterer will advise details of using his weather routing service. In the absence of such advice, the owner should utilise weather routing to minimise weather damage to the ship and cargo and weather stress on the crew.
    Allowance for ice conditions must be made in planning the voyage. Non-ice-classed ships must remain well clear of any area where consolidated pack ice is likely to occur. If an area subject to ice must be approached, then the master must obtain the best and most recent ice information from local authorities. Additional lookouts may be necessary if the vessel is passing an area where ice is suspected or reported, especially bergs or floes. Vessel speed must be adjusted at night in accordance with SOLAS 1974, Chapter V, Regulation 7. When a ship must transit pack ice conditions the appropriate icebreaker service must be contacted to arrange escort. If icebreaker services are arranged in convoys, the ship must follow the instructions of the controlling icebreaker.
    Masters unfamiliar with ice navigation should engage an ice pilot for that portion of the voyage. If a dedicated icebreaker escort is not available, the ship must wait for the next ice convoy. The master always retains full authority to abandon a voyage if, in his judgment, the ship would be exposed to serious danger in proceeding as planned. The master should keep in mind that although some time is lost by abandoning a voyage, this will be less costly for the owner than ice penetration of the hull with resulting oil pollution and damage repair costs.

    2.7.6 Prohibited zones
    Tankers which will wash tanks and decant slops or dirty ballast during the voyage must plan a route which places them outside coastal or oceanic prohibited zones long enough to conduct these operations within the requirements of MARPOL.

    2.7.7 Oceanic currents
    Tankers which will prosecute their voyages at reduced speed should carefully examine the prevailing currents for the waters to determine if the voyage plan can be adjusted to avoid adverse currents or make the best use of favourable ones. For example: when proceeding northbound on the southeastern US coast, Gulf Stream 'western wall' advisories can be obtained from shore radio stations. By setting a slow-speed vessel's track ten miles to the east of the Gulf Stream's 'western wall' considerable additional distance can be made at no additional cost in fuel.

    2.7.8 Pilotage
    The requirement for a voyage plan includes the portion of the voyage which will be completed under pilotage. The master should prepare a departure and arrival plan which includes pilotage waters and review the plan with the pilot before proceeding.

    2.7.9 Bunkers
    The master, in conjunction with the chief engineer and the first officer, must calculate and confirm that the bunkers carried are sufficient for the voyage to be undertaken. This calculation requires that the true caloric content of the fuel and the operational losses be considered. Recommended reserves should never be less than three days for full speed steaming, and will vary with the length of the voyage and the season of the year.
    Any fuel conservation programs required by charterer's should be followed diligently by the master and chief engineer.

    2.7.10 Timing of arrivals
    Unless otherwise instructed by charterer's, masters should proceed at the indicated speed to the arrival port, even though it is apparent that there will be a delay after arrival. The reasons for this are:

  • The arrived vessel may use the time to conduct necessary repairs or maintenance,

  • The ship will reserve an earlier position in the berthing order where 'first come - first berthed' procedures apply and

  • The anticipated spare time may be consumed en route by weather, mechanical or traffic delays.
  • 2.7.11 Publications
    Master and owner have a responsibility to ensure that a comprehensive set of the latest navigation publications are provided to the vessel. Notices to mariners and publication changes must be obtained when published and dispatched to the ship's next destination by the quickest method.

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