31st March 2016


Initial Report

What did the reporters tell us?

The reporter’s ship, a VLCC, sights an overtaking vessel astern at 3 nm closing on an apparent collision course in open sea. VHF calls elicit no response. The other vessel makes a small alteration to port and eventually passes the VLCC at a range of 5 cables, having crossed her stern. Extracts from the information passed to CHIRP. ‘The [other] vessel was overtaking at a speed of 18.7 knots (own ship 11.1 knots) and appeared to be heading directly for my own vessel’s accommodation block. At this point, [the other ship] was approximately 3 miles away. Attempts to contact [the other ship] to ask for their intentions were met with no response. We engaged hand steering and put the second steering motor on in preparation for any required action on our part. [The other ship] was then observed to make a small course alteration to port, meaning she would pass close astern. Final CPA was 5 cables, which in open sea is both dangerous and unacceptable’.

The lessons to be learnt

A burdened vessel (in terms of the COLREGS) fails to make her intentions clear, thus introducing doubt into the minds of those on the latter bridge. Though the use of VHF radio is not generally recommended in collision avoidance, the fact that the reporter’s VHF radio communication call went unanswered would have added further concern. Such doubt entered the mind of the ship being overtaken that she took steps to be ready for an emergency manoeuvre. Safe distance. The overtaking rule (13) requires the overtaking ship to ‘keep out of the way’. Even the passing distance (after course alteration) of 5 cables understandably seems too close to the reporter. This is often a matter of judgement and experience; a more objective way to think about it is to visualise what would happen if either ship had a machinery or steering breakdown. Would a close quarter situation be avoided by virtue of distance? If not, the CPA is too close. It is usually bad practice, when overtaking another ship, to approach her from dead astern, if only because this may put the overtaker in the other’s ‘blind arc’. Again – always think: ‘what if I/she had a machinery breakdown?’ A CHIRP Maritime Advisory Board member, when reviewing this case, recalled an occasion at sea when a ship ahead experienced propulsion failure. Our expert altered course, overtook, slotted in ahead. His own ship then suffered a mechanical breakdown. In this example it is not impossible that both ships were heading for the same waypoint, or converging on a likely point of shipping concentration. If so the overtaker should have been aware of the fact, and doubly alert. ‘Red-line-itis’ may also have been in play: ‘follow the planned track regardless’. Likewise dependence on bridge electronics may have dulled the judgement of CPA which would have resulted from visual assessment.

CHIRP Suggests

The lessons to be Don’t approach from dead astern when overtaking. Make your intentions clear in plenty of time. Avoid introducing doubt. Allow ample room. What would happen if either ship experienced a steering or propulsion breakdown? If a close quarters situation is the answer, too little room has been allowed. Keep a good lookout all round, including astern, and be aware of blind arcs. Monitor all vessels, especially those whose intentions are unclear.

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