Target Not Detected

31st October 2010

Target Not Detected

Initial Report

Report Text:

I was in my yacht with one other person, motor-sailing at about four knots in company with another yacht.  At about 1030 hours, we sailed into fog, with visibility about 100 yards.  My radar was detecting other vessels at about 4 mile range.

At 1140 hours, I received a VHF call from the accompanying yacht, which was half mile away to port, that he had detected, by radar, a fast moving vessel crossing ahead of him, which could be coming towards my vessel.  My radar screen showed nothing in that direction.  At 1145, a dark shape appeared through the fog square abeam to port.  Within seconds it passed astern of me at a distance of 20 yards maximum, disappearing into the fog as quickly as it came. It was probably a small fishing vessel, some 30 feet long, of the type commonly used for angling parties.  No name could be seen.  Estimating another vessel’s speed in such conditions is unreliable, but it was excessively fast in the conditions, and could have been 18-20 knots.

We continued the passage with no further incident.

Lessons learnt:

  1. My radar picked up no return from the other vessel, possibly because its aspect was “bows on”. i.e. radar cannot be assumed to be the perfect early warning system in bad visibility.
  2. Having received the warning from the other yacht, I couldn’t decide whether to hold my course and speed, or turn away to present a smaller “end-on” target.
  3. I should have immediately called the angling vessel to ascertain his name and home port, but I didn’t.

CHIRP Comment:

To comply with the ColRegs, in particular Rule 19 (Conduct of vessels in restricted vessel), both vessels should have been proceeding at a safe speed.  It would appear the yacht’s speed of 4 knots was prudent, but the fast speed of the other craft was not.  Both vessels should have been sounding fog signals.

As the yacht could not observe the angling boat and could not determine her course, the yachtsman was not able to determine whether an alteration of course would improve or worsen the situation.  As an alteration may have resulted in confusion, we are inclined to think that the best option was to maintain course.

It is not apparent that, in the short time the yacht had available, making a VHF call to an unidentified vessel would have achieved anything.

In Issue 23 of CHIRP MARITIME FEEDBACK, we included an editorial on “Defensive Sailing”.  In an encounter with a fast boat in fog where you are unable to determine whether collision is imminent, we would suggest that the following precautions for consideration:

  1. Everyone to be in the cockpit or on deck.
  2. If you are not already wearing lifejackets in accordance with the RNLI guidance, do so now!
  3. Plot your vessel’s position so that if there is a collision, you will have the information immediately available.

We are surprised that the yacht was not able to detect this target at any time on her radar and wonder whether the equipment was performing properly.  We note that the accompanying yacht was able to detect the angling boat by radar.  In the reported wind conditions of force 2 to 3 with slight sea, so we would not expect that the target would have been lost in sea clutter.  We have recommended to the reporter that, on a suitable clear day, he should observe other vessels within a radius of a few miles both visually and by radar.  If the radar is not picking up targets that can be seen visually, a service engineer should be called.

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