Is there such a thing as a radar assisted collision? The point of having radar available on a yacht is to avoid collision. And, providing the operator knows how to use it, radar is a great aid to safety, especially when visibility is poor.
One of the most impressive parts of a radar course I attended recently at Raymarine's Portsmouth headquarters was a simulation based on the MAIB report into a collision between a yacht and a container ship in the Channel in thick fog.
As is nearly always the case when collisions occur, the report suggested that neither the ship nor the yacht could be held wholly to blame for the incident.
The yacht was equipped with radar, but perhaps the crew did not altogether understand how to interpret the screen. The ship was going too fast (27 knots!) in almost zero visibility. Each had seen the other on their radars.
Had the yacht put an EBL (electronic bearing line) on the ship's echo, it would have shown that if she did not alter course or speed she would pass safely 0.8 miles ahead of the ship. The ship saw that the yacht would pass that far clear ahead and initially saw no cause for concern.
However, the skipper of the yacht apparently looked at the rapidly approaching target on the screen, and concluded that the ship was on a collision bearing. He therefore slowed down and stopped (he was motoring, as there was no wind), thinking this would allow the ship to go ahead of him. In fact it put him right in the path of the ship.
At the last moment, he saw the ship - on the opposite side of the yacht from where he was expecting it, because having lost steerage way, the yacht had turned, a fact the crew were unaware of, owing to the disorientating effect of the fog. And having lost steerage way, the yacht was unable to power out of the ship's way, and was run down. Fortunately, all the crew managed to climb into the liferaft unharmed before the yacht sank.
The ship had been going too fast to stop in time to prevent the collision, and had not steered out of the way because as the yacht was behaving in an unexpected way, the watch officer did not know which way to steer to avoid it.
Watching the simulation of this sobering incident on the radar screen prompted a thought-provoking discussion about how the people present would have reacted, in the same circumstances.
Even with the reassurance of an EBL showing you would pass ahead, it was widely felt that this was not the best course, especially in view of the ship's speed.
“Do a starboard 30 and go behind,” was one suggestion. The corrections were fed in, the simulation run again, and the 30 degree turn took the yacht behind the ship, but still clearing by less than a mile.
“Thirty degrees isn't enough,” said another voice. “I always do 45 or 90. Here I'd do port 90.” So the simulation was replayed again - and port 90 resulted in another running down!
It was hugely instructive to be able to conduct such experiments in the safety of the classroom. The lesson we all took away was that in such close quarters situations, it pays to go on watching the radar (an omission apparently made by the yacht in question.)
The point was made that tools like EBL and MARPA (mini automatic radar plotting aid, which gives information about the course, speed and closest point of approach of a target), should not be regarded as any more than an extremely useful guide. They should never be wholly relied upon.
Especially in fog, when normal collision regulations don't apply, the only thing that matters is staying out of danger - keeping all targets at a safe distance. Slowing down (or speeding up) can be a valid tactic to achieve this. But one thing everyone agreed on: you mustn't lose steerage way, and with it the ability to respond to things you see on the water, as well as on the radar screen.
