COLREG Rule 34 Signals When In Sight In A Narrow Channel

Extract from RULE 34 Manoeuvring and warning signals
(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 ‘! intend to overtake you on your starboard side“;

two prolonged blasts followed by two short blasts to mean “1 intend to overtake you on your port side“;

(ii) the vessel about to be overtaken when acting in accordance with Rule 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.

(d) When vessels in sight of one another are approaching each other and from any cause either vessel fails to understand the intentions or actions of the other. or is in doubt whether sufficient action is being taken by the other to avoid collision. the vessel in doubt shall immediately indicate such doubt by giving at least five short and rapid blasts on the whistle. Such signal may be supplemented by a light signal of at least five short and rapid flashes.

(f) If whistles are fitted on a vessel at a distance apart of more than 100 meters. one whistle only shall be used for giving manoeuvring and warning signals.