Observer
Well-Known Member
Last week we made a passage from the Solent to Guernsey. Crossing the SW bound shipping lane, we encountered some traffic and ended up in a situation not dissimilar to that posed in this WNS thread.
We were crossing on a heading of (say) 180º and a ship (I'll call it Ship A) was approaching from port on a heading of (say) 270º. We were making ~18kts. Time was ~1200 and visibility was excellent. We are not in a TSS. Whilst Ship A was still a considerable distance away (>3nm according to radar), I assessed (by eye) that we were on a possible collision course. Obviously I was the stand on vessel. I decided to maintain course and speed in accordance with colregs and see how things developed. There was another ship (Ship B) to port of Ship A, on about the same heading but moving faster and I assessed that it would comfortably pass ahead of us. There was also another ship (Ship C) behind and to starboard of Ship A but it was clear that we would comfortably pass ahead of it. At the time we were ~1nm east of our straight line track to Alderney, due to tidal effect, that I had deliberately decided not to correct, expecting a compensating push back to the west when the tide turned.
A few minutes passed and I could not see any appreciable change in the bearing of Ship A, so wondered if he intended to take avoiding action, but decided to wait a bit longer. A further few minutes passed and, according to MARPA, CPA was <0.1 nm. I'm now somewhat doubtful that Ship A is going to take action and the bearing (by eye) is very steady. There's no actual danger because the distance is still >1nm so I have plenty of time to take action if needed. Ship B is now directly ahead and crossing and Ship C is still a long way off.
A further period passes and the bearing to Ship A is still steady (perhaps reducing a little) and the MARPA alarm ("dangerous contact") sounds, although the distance is still ~1nm. There is no real danger or concern but I decide that I will take action because Ship A doesn't appear to be. I assess that we will pass just ahead, but too close for comfort. MARPA did show a speed for Ship A but I find it hugely erratic so don't take much notice of it. I assess the possibilities:
A) turn to port on reciprocal track (090º) to Ship A then, when appropriate, pass behind him
B) do 180º turn and pass behind Ship A
C) slow down or stop to allow Ship A to pass ahead
D) turn 90º to starboard on to parallel heading then re-assess
My instinct was option A. There was still plenty of distance between us (we were at least 0.5nm north of the track intersection), and I knew I could easily progressively turn to starboard to track Ship A's stern so slip behind without going too far east of our desired track. Ship C was a possible concern as it was further north than Ship A but it was still a long way (>3M off) so I was happy that we would not interfere with her.
I considered B but concluded that the time to do a 180º turn would not change things materially. Would it 'look' better to accomplish A by a 270º turn to starboard? Possibly but, imo, it makes virtually no practical difference.
I considered and dismissed C, partly because I felt it unncessary and wasteful to incur the cost of coming off the plane and getting back on. I also considered it unwise to 'loiter' in front of Ship C.
I remembered the WNS thread above and that the "expert" view was, in essence, option D (90º turn to starboard). So, somewhat against my own judgment, I went for option D with the intention of either waiting for Ship A to overtake or closing Ship A's track gradually then, if sufficiently far ahead, turn 90º to port and cross ahead. After a few minutes, it became clear that our speeds were closely matched - the distance between us and Ship A was not appreciably changing but it was still >0.5nm off. I was (probably wrongly) reluctant to change my decision so, instead, I pushed the speed up by 2kts or so to increase the gap.
Well, it took about 10-15 minutes at the higher speed before the gap had widened sufficiently for me to judge it prudent to cross ahead of Ship A, and for much of that time I was looking over my shoulder to see what was happening. I did cross ahead of it without incident and resumed our course, but we were now about 2nm west of the straight line track instead of 1nm east.
My conclusion is that option A was a better choice. It would have kept Ship A firmly in the windscreen and the avoidance process would have take perhaps a minute or two instead of ten to fifteen. With respect to whoever advised Tony Jones, I can't see anything wrong, in these circumstances, in the port turn provided there is still plenty of time and sea room to re-assess if needed. Next time I will follow my judgment.
We were crossing on a heading of (say) 180º and a ship (I'll call it Ship A) was approaching from port on a heading of (say) 270º. We were making ~18kts. Time was ~1200 and visibility was excellent. We are not in a TSS. Whilst Ship A was still a considerable distance away (>3nm according to radar), I assessed (by eye) that we were on a possible collision course. Obviously I was the stand on vessel. I decided to maintain course and speed in accordance with colregs and see how things developed. There was another ship (Ship B) to port of Ship A, on about the same heading but moving faster and I assessed that it would comfortably pass ahead of us. There was also another ship (Ship C) behind and to starboard of Ship A but it was clear that we would comfortably pass ahead of it. At the time we were ~1nm east of our straight line track to Alderney, due to tidal effect, that I had deliberately decided not to correct, expecting a compensating push back to the west when the tide turned.
A few minutes passed and I could not see any appreciable change in the bearing of Ship A, so wondered if he intended to take avoiding action, but decided to wait a bit longer. A further few minutes passed and, according to MARPA, CPA was <0.1 nm. I'm now somewhat doubtful that Ship A is going to take action and the bearing (by eye) is very steady. There's no actual danger because the distance is still >1nm so I have plenty of time to take action if needed. Ship B is now directly ahead and crossing and Ship C is still a long way off.
A further period passes and the bearing to Ship A is still steady (perhaps reducing a little) and the MARPA alarm ("dangerous contact") sounds, although the distance is still ~1nm. There is no real danger or concern but I decide that I will take action because Ship A doesn't appear to be. I assess that we will pass just ahead, but too close for comfort. MARPA did show a speed for Ship A but I find it hugely erratic so don't take much notice of it. I assess the possibilities:
A) turn to port on reciprocal track (090º) to Ship A then, when appropriate, pass behind him
B) do 180º turn and pass behind Ship A
C) slow down or stop to allow Ship A to pass ahead
D) turn 90º to starboard on to parallel heading then re-assess
My instinct was option A. There was still plenty of distance between us (we were at least 0.5nm north of the track intersection), and I knew I could easily progressively turn to starboard to track Ship A's stern so slip behind without going too far east of our desired track. Ship C was a possible concern as it was further north than Ship A but it was still a long way (>3M off) so I was happy that we would not interfere with her.
I considered B but concluded that the time to do a 180º turn would not change things materially. Would it 'look' better to accomplish A by a 270º turn to starboard? Possibly but, imo, it makes virtually no practical difference.
I considered and dismissed C, partly because I felt it unncessary and wasteful to incur the cost of coming off the plane and getting back on. I also considered it unwise to 'loiter' in front of Ship C.
I remembered the WNS thread above and that the "expert" view was, in essence, option D (90º turn to starboard). So, somewhat against my own judgment, I went for option D with the intention of either waiting for Ship A to overtake or closing Ship A's track gradually then, if sufficiently far ahead, turn 90º to port and cross ahead. After a few minutes, it became clear that our speeds were closely matched - the distance between us and Ship A was not appreciably changing but it was still >0.5nm off. I was (probably wrongly) reluctant to change my decision so, instead, I pushed the speed up by 2kts or so to increase the gap.
Well, it took about 10-15 minutes at the higher speed before the gap had widened sufficiently for me to judge it prudent to cross ahead of Ship A, and for much of that time I was looking over my shoulder to see what was happening. I did cross ahead of it without incident and resumed our course, but we were now about 2nm west of the straight line track instead of 1nm east.
My conclusion is that option A was a better choice. It would have kept Ship A firmly in the windscreen and the avoidance process would have take perhaps a minute or two instead of ten to fifteen. With respect to whoever advised Tony Jones, I can't see anything wrong, in these circumstances, in the port turn provided there is still plenty of time and sea room to re-assess if needed. Next time I will follow my judgment.
but learning fast 
