One short blast. What does it mean?
«I am altering my course to starboard».
Rule 34 (a).
Part of the convention Sound and light signals
In sight of one another, a power-driven vessel underway signals her manoeuvre on the whistle: one short blast means altering to starboard, two short altering to port, three short operating astern propulsion. The same meanings may be repeated with flashes of an all-round white light.
- Overtaking in a channel: two prolonged and one short means intending to overtake on your starboard side, two prolonged and two short on your port side. The other vessel agrees with prolonged, short, prolonged, short.
- At least five short and rapid blasts (and flashes if you like) mean «I do not understand your intentions» or «I doubt whether you are taking sufficient action». Sound it immediately.
- Approaching a bend in a channel: one prolonged blast, and any vessel round the bend within hearing must answer with the same.
- If whistles are fitted more than 100 m apart, only one whistle is used for manoeuvring and warning signals.
At sea it looks like this
She is on your starboard side, must give way, and is not turning. Five short blasts is not swearing, it is the rule-book way to say «your actions are unclear to me», after which you may act on your own.
The rule says«When vessels are in sight of one another, a power-driven vessel underway, when manoeuvring as authorized or required by these Rules, shall indicate that manoeuvre by the following signals on her whistle: one short blast to mean “I am altering my course to starboard”; two short blasts to mean “I am altering my course to port”; three short blasts to mean “I am operating astern propulsion”».
Sound signals
Sound signals
•«I am altering my course to starboard»
• •«I am altering my course to port»
• • •«I am operating astern propulsion»
• • • • • …«I do not understand your intentions» or «I doubt you are taking sufficient action»
▬ ▬ •«I intend to overtake you on your starboard side»
▬ • ▬ •Agreement of the vessel being overtaken: «go ahead»
▬I am approaching a bend where other vessels cannot see me
Check yourself
Two short blasts. What do they mean?
«I am altering my course to port».
Rule 34 (a).
Three short blasts. What do they mean?
«I am operating astern propulsion».
Rule 34 (a).
At least five short and rapid blasts. What does that mean?
«I do not understand your intentions» or «I doubt whether you are taking sufficient action». Sounded immediately, and may be joined by flashes.
Rule 34 (d). It is not a distress signal.
Two prolonged and one short blast. Where and what is it?
In a narrow channel or fairway only: «I intend to overtake you on your starboard side». Two prolonged and two short means on your port side.
Rule 34 (c) (i).
Prolonged, short, prolonged, short. Who sounds it and why?
The vessel being overtaken in a channel: «agreed, come through», and she then takes steps to permit safe passing.
Rule 34 (c) (ii) and 9 (e) (i).