West of England P&I – Loss Prevention Placards
Two new placards have been added to the West of England Club’s Radar Best Practice series of Loss Prevention placards, produced in association with Northrop Grumman Sperry Marine.
The new placards address the numerous points that should be considered by Deck Officers when using Automatic Radar Plotting Aids (ARPA) for collision avoidance:
When using the ARPA the following points should be considered:
- For collision avoidance purposes an ARPA should be sea stabilised with a log input delivering the vessels speed through the water. The resulting true vectors will provide a more accurate indication of the aspects of tracked targets. If speed through the water is set manually, the details should be checked regularly and updated as necessary. Remember that GPS speed is the vessels speed over the ground
- It should be borne in mind that the relative motion of a target, and therefore its Closest Point of Approach (CPA), Time to Closest Point of Approach (TCPA), Bow Crossing Range (BCR) and Bow Crossing Time (BCT) should remain the same regardless of radar set-up, provided the vessel and the target maintain their course and speed
- Compass heading and speed errors will produce inaccurate target true vector data, particularly when another vessel is on a reciprocal or near reciprocal course. This may lead to an incorrect interpretation of the other vessels true heading and the necessary collision avoidance action
- If guard zones or target acquisition areas are used, bear in mind that these features are no substitute for maintaining a proper lookout by sight, hearing and all other available means to ensure the early detection of other vessels
- Relative target trails which are sufficiently distinct may provide an early indication of whether a close quarters situation is developing and/or if risk of collision exists
- Some ARPAs may not be able to track small, high speed craft accurately, and it is possible that such targets may be lost
For more information please view theLoss Prevention Placards below:
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Source and Image Credit: West of England Club
