A case study in collision avoidance
A ro-ro passenger ferry was on her regular passage from Southampton to Cowes, it was daylight and the visibility was good. The wind was south-easterly force 4 and the tidal stream was easterly.
The ferry left the Thorn Channel and headed south-south-westerly across the western part of the Bramble Bank towards the West Knoll buoy with the intention of leaving it to port. She would then head towards the South Bramble buoy. She was making good between 12 and 13knots.
A sailing yacht, the closest of four yachts crossing the Bramble Bank ahead of the ferry, was making about 6 knots on a close reach and, although on a more westerly heading than the ferry, was making good a similar track. The other three yachts were making similar tracks but further to the west.
Assuming the yacht would maintain her heading, the ferry's master considered he would be able to overtake her on her port side soon after she had passed the West Knoll buoy. There was only just enough sea room for this manoeuvre, but the ferry master knew that he could stop or slowdown rapidly if necessary. Staying clear of the main area of congested leisure traffic further to the west was another consideration.
The skipper of the yacht was watching the approach of the ferry with some alarm. He was aware that unless the ferry altered her course or speed very soon his vessel would be run down. He could not be sure that the watchkeeper on the ferry had seen him.
When the yacht was about 1 cable ahead, the ferry began to alter course to port as planned. However, by this time, the skipper of the yacht had become so concerned that he also had begun to alter course to port. The skipper considered that his own vessels close proximity to the West Knoll Buoy ruled out the possibility that the ferry would pass down his port side. With this in mind, his intention had been to tuck up closer to the buoy to give the ferry more room to pass him on his starboard side.
The combined effect of the two actions was to maintain both vessels on their collision course. The ferry's master sounded two short blasts, with the intention of altering course further to port, but immediately decided that it would be better to pass down the starboard side of the yacht. He stopped his vessel swinging further to port accordingly.
The ferry passed only a few metres clear of the yacht when she was just over half a cable south of West Knoll Buoy about 1 minute after beginning his anti-collision manoeuvre.
The lessons
Anyone who has sailed in the Solent, or been on passage through it in a larger vessel, will know that it can get quite exciting; especially in summer. It demands a very high degree of concentration and nowhere more so than in the area to the north of Cowes. Its limited area, and simultaneous use by merchant vessels, ferry operators, warships and leisure craft effectively restricts the available sea room in which to comply with the Collision Regulations, and vessels have differing perspectives of the requirements.
1. The action taken by the ferry
In accordance with Rule 13 of the Collision Regulations, the ferry was required to keep out of the way of the yacht. In accordance with Rule 17, the yacht was required to maintain her course and speed until it became apparent that the ferry was not taking appropriate avoiding action.
The Collision Rules variously call for the action of the give-way vessel to be:
- positive, made in ample time and with the observance of good seamanship;
- large enough to be readily apparent to another vessel;
- such as to result in passing at a safe distance; and
- early and substantial.
Appropriate avoiding action can be measured against these requirements.
The master of the ferry's planned anticollision action did not fulfil many, if any, of the above requirements. Bearing in mind the ferry's ability to slow down and stop very rapidly, more appropriate avoiding action in these circumstances might have been to have slowed down until both vessels were well past West Knoll Buoy where greater sea room would have enabled a safer passing manoeuvre.
2. The action taken by the yacht
Compliance with Rule 17 (maintaining her course and speed until it became apparent that the ferry was not taking appropriate avoiding action) can place the yacht, or any other slow speed stand-on vessel, in a very difficult position.
At what stage can the skipper of a stand-on yacht legitimately decide that the give-way vessel is not taking appropriate avoiding action? In this case, with the two vessels only a cable apart, and therefore within a minute of colliding, and the give-way vessel having shown no sign that he had the situation under control, the skipper was justified in taking action. As the yacht was already close to West Knoll buoy, an alteration of course to port towards the buoy was the most obvious choice, but any alter course action stood the risk of making matters worse. Rule 34 contains sound signals for this situation and it is important to make every effort to communicate intentions to the other party.
3. The importance of communication
Early use of the sound signal of two short blasts would have indicated the ferry's intentions under Rule 34 of the Collision Regulations. In the absence of a positive early indication of the intentions of the give-way vessel, the skipper of the stand-on yacht needs reassurance that the watchkeeper of the give way vessel has seen him. Under Rule 34,the skipper may try to attract the attention of the give way
vessel by sounding five or more short blasts using the boats sound signalling equipment and/or flashing a signal light. This signal indicates that you are in doubt as to whether sufficient action is being taken. Because the ferry had an enclosed bridge, flashing the light might have been the more effective signal on this occasion.
Reproduced by kind permission of the Marine Accident Investigation Branch. Originally published in MAIB Safety Digest 3/2002.
www.maib.dft.gov.uk
