Mutual misunderstanding?

Report Text

In the afternoon when approaching port we noted a tanker approaching from the southwest. It was clear from its change of bearing that it intended to pass astern of us.

However, without any signal, it altered to port as if trying to pass ahead of us.

I tried calling on 16 to establish his intention, e.g. “Tanker 10 miles south of AAA this is yacht “XXX” fine on your starboard bow: what are your intentions?” No reply. Once again the bearing became steady so at about 1/2 mile distant I was obliged to alter to port and onto the starboard tack so that she was able to pass clear ahead of our intended track. He clearly had underestimated our speed.

I called again after he was clear. This time there was a reply and I told him that he had caused immense worry and confusion by altering course to port to try to pass ahead of us. I think I heard the words “Thank you”!!

There was no hurry as the ship stood off for the rest of the day and did not enter port until the evening.

Perhaps big ship’s Officers of the Watch should be invited to spend time on small craft in busy sea lanes. They might learn something.

CHIRP Comment:

This report was sent to the tanker’s operator, who asked the master to respond:

“Regarding to CHIRP report kindly please find my explanations:

1) Vsl has been ordered from Port Control to remain 10 Nm outside Port Limit await for pilotage.

2) Due to above Vessel steamed with slow speed and var. courses.

3) At that time Bridge watch was fully equipped and we not see any serious problem to make a safely pass with small yacht. We heard on Vhf Ch 16 that some station calling a tanker within this area but usually we are not going to making any conversation for such situation with others station.

4) Vsl has been changed the course and all the time kept safely distance CPA of more 0.5 Nm”

The reporter responded to this with:

“I would comment on each paragraph as follows:

  1. As previously stated, our encounter was, indeed, about 10nm south of the port;
  2. I would not rate the tanker’s speed as particularly slow as she was creating a fair bow and stern wave in, from our point of view, a moderate sea. However, later in the day, we did note that she was going slow speed before approaching the pilotage ground;
  3. It was perverse of the tanker to have altered course towards us in open sea conditions. She gave no indication (visual or sound) that she had seen us. A series of 2 flashes on his Aldis (or blasts on the siren) would, at least, have indicated that she knew what she was about. It is my guess that the ship altered course before she was aware of our presence. We know that our ‘blipper’ radar reflector is effective up to 6 miles so she should have sensed us;
  4. The distance off ahead may well have been as much as 0.5nm, but that did not lessen the alarm experienced from such an unusual and thoughtless manoeuvre when the tanker had the entire Channel in which keep his distance off the port and us.”

The issue of passing distances generates a good number of reports to CHIRP, but there is a great deal of subjectivity in the individual assessments made and the other party does not always reach the same conclusion, as this correspondence demonstrates.  The Maritime Advisory Board makes the following observations:

  • An alteration to starboard by the tanker would have been appropriate.
  • There is a need to try and evaluate the situation from the other vessel’s perspective; it may be reasonable to ask the question “How close would I like someone to be if I were on the other ship/boat?”
  • This report and others we have published features a Radar Target Enhancer (RTE). The majority of RTE operate on the X band (3cm); merchant vessels also operate S band (10cm) radars and whilst the X band radar is commonly used for coastal work it may not be the radar being observed.  RTE’s can undoubtedly help, but they should not be relied on in making an assessment as to whether you have been seen or not.