In drawing up a Passage Plan, the Master shall NOT be too much swayed by how to shorten the distance but Select an Optimal ship track
Ocean and Open Waters
Enter the planned ship track on a small-scale chart to obtain its approximate distance. The following are among the points to be considered when setting ship course line:
- Select an optimal ships course. (Great Circle , Composite or Rhumb. Line in the order of preference, subject to prevalent weather conditions)
- Use information from Sea and Weather forecast and, in case a Weather Service is adopted, information on recommendable Ships Routing.
- Besides above analyzing , the Master shall select the route which is expected Minimum Fuel Consumption and Minimum Hours Under Way.
Coastal and Restricted Waters
In the case of coastal and restricted waters navigation, there are certain restrictions on the navigation of ships due to the available width of channel, water depth, heavy shipping traffic, IMO traffic separation schemes etc.
Following shall be considered when drawing up the course line
While safely navigable waters are restricted by such factors as draught, under keel clearance and tidal conditions, there are some Cautionary Zones called ‘No-Go Area’ where the ship cannot navigate safely. These areas must be shown by cross hatching (using only Pencil) in regions close to charted track.
To minimize the risk of getting stranded even in the occurrence of trouble on the Engine or Steering system, secure as much distance as possible from the Cautionary Zone.
Put down the Distance off Clearly on the chart using Parallel Indexing from the obstacles.
Around the No-Go Area, secure Safe Water where the ship can navigate safely by taking Margins of Safety into consideration.
In determining Safe Water consider the following :
Ship conditions such as Draft and Maneuvering Performance Effects of Ocean stream, Tidal current and Tide Under Keel Clearance Distance off from the Shallow waters, Obstacles etc
Under Keel Clearance (UKC)
UKC through the voyage, shall be kept in principle, at least 20% of the Ships Draft In Restricted Waters such as Ports, Canals or Fairways, the UKC maintained must be at least 10% of the ships draft. Depending upon the circumstances, however, it is necessary to greatly increase these margins.
When determining Under Keel Clearance , consider these points:
- Squat of the ship due to Shallow water effect and the necessity to Reduce Speed to decrease its effect
- The vessels Heeling (due to Wind or Turning) and Pitching movement
- Reliability of Charted Depth Data
- Predicted Tidal Levels including if any expected Negative Surge
- Areas of Mobile Bottom (Silting / Sand-waves)
- Any change in Water Density in passage (and its effect on draft)
- Accuracy of Actual Draft
- Reduced depths over Pipelines and other Obstructions
In the rare instance when a vessel is required to enter the port with UKC of less than 10%, the Master is to notify the managing office prior transit. He should also do so if he is in any doubt that sufficient clearance can be maintained throughout the voyage.
Special UKC policy for VLCC & Deep Draught vessels Transiting through Malacca straits & Singapore straits (Shall be complied in addition to above):
- Maximum permissible loading draught by the Company is restricted to 20.50 meter, while transiting the Malacca / Singapore Straits
- Follow Local regulations as per Rules for the Straits of Malacca & Singapore Straits
- VLCCs on her laden voyages can pass BUFFALO ROCK (Singapore) during the Daytime High Tide only.
- Minimum allowable UKC to maintain when passing entire passage is 3.50 meter (One Fathom Bank and Buffalo Rock),
EXCEPT when passing EASTERN BANK, in the season of North-East Monsoon at the South China Sea, where Minimum allowable UKC to maintain is 4.00 meter.
Where the waters are affected by large tidal variation, adequate UKC may sometimes be attainable only during the period that the predicted tide has achieved a given height and vessel would need to wait for the suitable time to Cross the Bar.
Course alteration & wheel over positions
Alteration points should be marked off with bearings/ranges of terrestrial targets and/or geographical coordinates. Wheel over positions shall be marked using ships maneuvering data while navigating in confined waters and large scale charts.
This is useful method of monitoring cross track tendency in any condition of visibility. It is a particularly valuable tool approaching port and during pilotage when the master is able to continually monitor the vessels position in this way while the OOW plots the position obtained from other data.
Aborts and Contingencies
Even if a Passage Plan has been well planned and conducted, there may be some cases in restricted waters when the Passage Plan will have to be abandoned due to change in circumstances (like equipment failure, port instructions etc)
The Abort Point is a position to be marked on the charted course where the ship may abandon her passage and be able to return (or hold position safely).
Take care when marking an abort. At the abort position, there should be sufficient sea room for the ship to undertake any of the following maneuvers in safety:
Turn around Stop in safe waters Anchor
Once this point is passed , the ship is committed and must continue on the passage.
Contingency Planning by the Master shall be done in advance which may include Alternative routes, Safe anchorages, Waiting areas, Emergency berth etc., after passing the Abort Point.
The frequency of the position fix, as a maximum, should be such that the ship is kept free from danger between fixes and if a deviation occurs, avoiding action can be taken to guarantee the safety of the ship.
Other information may be included in passage plan such as reporting points, Pilot boarding area, Tug engagement, Heavy traffic area. Also, Anecdotal information to be included basis previous voyages or experience.
Changes or deviation in passage plan
Any changes or deviation made to the plan should be made consistent with this procedure. Bridge team meeting shall be held & new supplementary passage plan shall be made to cover changes or deviation in route to ensure safe passage of vessel. Such changes or deviation clearly marked and recorded in Deck Log book.