Sound Signal Player
audioAltering course to starboard
Rule 34: Maneuvering and warning signals
Whistle/light manoeuvring signals communicate intentions clearly when vessels are in sight.
Detailed Explanation
(a) In sight, power-driven vessel manoeuvring signals: one short = altering to starboard; two short = altering to port; three short = operating astern propulsion.
(b) Signals in (a) may be supplemented by equivalent light signals with prescribed flash timing and range.
(c) In narrow channels/fairways overtaking intentions: two prolonged + one short (intend overtake on your starboard side) or two prolonged + two short (intend overtake on your port side). Agreement by overtaken vessel: prolonged-short-prolonged-short.
(d) If intentions/actions are not understood, or doubt exists about avoiding action sufficiency: sound at least five short rapid blasts (may add five rapid light flashes).
(e) Near bends/obstructions in channel: sound one prolonged; approaching vessel within hearing answers with prolonged.
(f) If whistles are >100 m apart, use one whistle only for these signals.
Key Points
- 1 short = I am altering to starboard
- 2 short = I am altering to port
- 3 short = engines going astern
- 5+ short rapid = doubt/danger signal
Examples
- In a narrow channel you intend to overtake on the other vessel's starboard side: you sound two prolonged blasts followed by one short blast per Rule 34(c)(i).
- You hear five or more short rapid blasts from a vessel ahead: this is the doubt/danger signal under Rule 34(d). You stop your approach and assess the situation.
- Your cargo ship alters to port in sight of another vessel. You sound two short blasts per Rule 34(a) to indicate your alteration to port. The other vessel acknowledges understanding.
Common Mistakes
- Confusing three short blasts (engines operating astern) with an intention to alter course.
- Failing to sound five rapid blasts when there is doubt about another vessel's actions.
- Forgetting that light signals may supplement whistle signals under subsection (b).