Here is why the trawler was absolutely WRONG. Under international rules sound signals are signals of execution and require no response. Under inland rules which cover every harbor and the Great Lakes sound signals are signals of intent and require a response signal. Since a paddle board won't be carrying a sound signal the necessary response will not be forthcoming. At that point there is only one option which is to sound the danger signal. The trawler did more to confuse an already tenuous situation and should have known better. Additionally his actions show a lack of ability to ascertain a risk of collision situation and alter his vessels movement before he felt the necessity to sound his horn.
Here's the definition of International Rules:
(a) These Rules shall apply to all vessels upon the high seas
and in all waters connected therewith navigable by seagoing vessels.
Here's the definition of vessel:
a) The word "vessel" includes every description of watercraft, including non-displacement craft, WIG craft, and seaplanes,
used or capable of being used as a means of transportation on water.
Narrow Channels:
Rule 9
(a) (i) A vessel proceeding along the course of a narrow channel or fairway shall keep as near to the outer limit of the channel or fairway
which lies on her starboard side as is safe and practicable.
(b) A vessel of less than 20 meters in length or a sailing vessel
shall not impede the passage of a vessel [ which | that ] can safely navigate only within a narrow channel or fairway.
(d)
A vessel shall not cross a narrow channel or fairway if such crossing impedes the passage of a vessel which can safely navigate only within such channel or fairway.
The thing you might be correct about is that the skipper of the trawler
might have used the wrong sound signal. In any event, the trawler was off my port stern/quarter so was more on the left side of the channel, not the right (starboard) side, which is where I was

. The SUP was across the channel off my port beam, so was more in the correct spot BUT was IMPEDING the on-coming trawler being practically stopped. [
However, I don't know what the application of this rule would be if BOTH are less than 20 meters length.] The trawler signaled with a single blast a turn to the right. To signal "I'm overtaking you..." WOULD have required a response which could not be given. [And not even understood.] So, maybe he was "honking." On the other hand, as pointed out--MAYBE the guy meant his signal for an approaching vessel and had nothing to do w/the SUP! Nevertheless, the SUP responded and more toward the path that the trawler skippered had indicated he was taking.
See BELOW;
(c) When in sight of one another in a narrow channel or fairway:
(i) a vessel intending to overtake another shall in compliance with Rule 9 (e)(i) indicate her intention by the following signals on her whistle: two prolonged blasts followed by one short blast to mean "I intend to overtake you on your starboard side" two prolonged blasts followed by two short blasts to mean "I intend to overtake you on your port side"
(ii) the vessel about to be overtaken when acting in accordance with 9(e)(i) shall indicate her agreement by the following signal on her whistle: one prolonged, one short, one prolonged and one short blast, in that order.
Tell me that would not have shaken up everybody in the channel at that time INCLUDING ME!!!