That would be my guess - it would be nice to warn folks that they're going to swing
around. Since the vessel was not strictly underway, I'm not sure its strictly required.

Maybe they were using a little reverse to straighten/reset the chain when the tide
changed. Is one actually "at anchor" at this point?

For leaving a berth: One prolonged blast (US Inland)
For a blind turn: One prolonged blast
For turn to starboard: One short blast (The meaning is slightly different in Intl and
Inland)
For "operating astern propulsion": three short blasts

I assume there was good visibility, so these weren't actually anchor signals.

"Donal" wrote in message
...
Yesterday, as we approached a large, anchored, oil tanker, it gave one
short blast. About a minute later it gave three short blasts.


Does anybody know what this meant?

At the time, there were few other boats in the vicinity. The tide was
about to turn. In fact the ship changed its attitude by 90 degrees over the
following 15-20 minutes. I noticed some smoke from the funnel for a couple
of minutes.

Do these ships "drive around" when at anchor? Would they indicate a
starboard turn, and then an astern signal?

I tried calling them up on the radio, but there was no reply.



Regards


Donal
--