The sound signals for situations other than signals specifically for restricted visibility are in Rule 34 (Manoeuvring and Warning Signals). This rule has several sub-rules that require careful reading. 

Most of the sub-rules require that “vessels are in sight of one another” before they can use particular sound signals, e.g., one, two, or three short blasts. Also, some of the sub-rules apply only to power-driven vessels (like our vessels). When other vessels cannot be seen due to restricted visibility, your vessel should not make sound signals that require that “vessels are in sight of one another”. This even applies to the “five short” signal where you indicate there may be some danger or that another vessel’s intentions are unclear. 

Note that the “five short signal“ may be supplemented by a light signal of “at least five short and rapid flashes”. Although the COLREGS do not specify, such flashing light signals should be synchronized with the blasts in the sound signals; one benefit of synchronizing the sound and light signals is that it will be clearer to others which particular vessel is sounding signals for uncertainty or danger when there are several possible vessels in sight. 

Note that Annex III 1(b) specifies that the whistles of larger vessels should be at a lower frequency. Thus the whistle of a BC ferry is much lower in tone than the horn of CAPE LAZO (and recreational vessels). 

Last modified: Sunday, 26 January 2025, 11:04 AM