COLREGs trainerPart D: Sound and Light Signals
Rule 35
PDV making way: one prolonged blast at intervals of not more than 2 min; many variants by vessel state.
Wording follows the International Regulations as printed in the US Coast Guard Navigation Rules handbook (2024), with British spelling, and is shortened in places. Download the rules
A power-driven vessel making way through the water shall sound, at intervals of not more than 2 minutes, one prolonged blast.
A power-driven vessel underway but stopped and making no way shall sound, at intervals of not more than 2 minutes, two prolonged blasts in succession with about 2 seconds between them.
A vessel not under command, restricted in her ability to manoeuvre, constrained by her draught, a sailing vessel, a vessel fishing, or one towing or pushing shall instead sound, at intervals of not more than 2 minutes, three blasts in succession: one prolonged followed by two short.
A vessel engaged in fishing when at anchor, and a vessel restricted in her ability to manoeuvre when carrying out her work at anchor, shall instead of the bell signal of paragraph (g) sound one prolonged followed by two short blasts at intervals of not more than 2 minutes.
A vessel towed (or the last vessel of a tow, if manned) shall, at intervals of not more than 2 minutes, sound four blasts: one prolonged followed by three short. When practicable, made immediately after the towing vessel’s signal.
When a pushing vessel and a vessel being pushed ahead are rigidly connected in a composite unit, they are regarded as a power-driven vessel and give the paragraph (a) or (b) signals.
A vessel at anchor (other than one under paragraph (d)) shall, at intervals of not more than one minute, ring the bell rapidly for about 5 seconds. In a vessel of 100 m or more, the bell is sounded forward and immediately followed by the gong sounded rapidly for about 5 seconds aft. She may also sound one short, one prolonged and one short blast to warn of her position.
A vessel aground shall give the bell (and if required gong) signal of paragraph (g) and, in addition, three separate and distinct strokes on the bell immediately before and after the rapid ringing. She may also sound an appropriate whistle signal.
A vessel of 12 m or more but less than 20 m in length is not obliged to give the bell signals of paragraphs (g) and (h). However, if she does not, she shall make some other efficient sound signal at intervals of not more than 2 minutes.
A vessel of less than 12 m is not obliged to give the above signals, but if she does not, shall make some other efficient sound signal at intervals of not more than 2 minutes.
A pilot vessel engaged on pilotage duty may, in addition to the paragraph (a), (b) or (g) signals, sound an identity signal of four short blasts.
A training aid, not the official text. The COLREGs are an IMO convention, and your national authority publishes the version that applies in its waters. Check the rules themselves before you rely on them at sea. Download the rules.