CHIRP Narrative: This report is from the Master of a supply vessel. He was acting as watch-keeper at the time of the incident.
The following incident took place in the Northern North Sea earlier this year at about 0750 hrs(UTC+1). It involved the failure of the give way crossing vessel to make any move to carry his obligations under rule 15 such that the stand on vessel had to take all the avoiding action. At 0700 hrs the plot was started on both the 3cm & 9cm radars of the target at about 8 miles out about 4 points on the port bow. Both displays were north up, relative 12min vector, true 6 min trails. The weather was heavily overcast with visibility of 5 miles: the wind was out of the north at force 6 / 7 with a rough sea and a mod to rough swell running. Own vessel was on passage to the ### Oil Field on a course of 043deg T speed 9.8 kts The target data gave the information that within the hour a collision situation would exist and the AIS gave details of the vessel concerned. The plot showed that his cog was 135 with an sog of 7.8 kts leading to a CPA of between O and 0.2 cable in about 48 mins. The angle of convergence of the two vessels was very close to ninety degrees thus making it and maintaining it as a crossing situation throughout the whole event. The other vessel held her course and speed during the entire close encounter such that at 8 cables own vessel halved speed allowing the give way to pass ahead by 0.42 cables. The other vessel never deviated from her course or speed giving the distinct impression that for some reason she was totally unaware of our close presence in broad daylight. She continued on her way oblivious to all.
No VHF contact was made at any time. Both vessels displayed nav lights for power driven vessel underway and making way and nothing else.
The other vessel appears to have contravened Rule 15 (Crossing Situation) of the Col Regs. We are communicating with the owner of the other vessel to invite his comment.
As with any close quarters situation, it is worth reflecting whether, as the stand-on vessel, we could have done anything differently. In this case, with the two vessels being within four cables of each other, the tug may have been at some risk, albeit small, if the other vessel had unpredictably altered course at the last minute. So would it have been appropriate to slow down somewhat to increase the passing distance?