COLREG - Manoeuvring and Warning Signals (Rule 34)
Sound and light signal pattern for intended manoeuvres or warnings per COLREG Rule 34.
Formula, assumptions, limits
COLREG Rule 34 prescribes sound signals for manoeuvres in sight of one another and for warnings. Signals may be supplemented by all-round white light flashes synchronised with the sound. Short blast = approximately 1 second; prolonged blast = 4 to 6 seconds.
Manoeuvring and warning signals
SituationSoundLightRule
Altering to starboardOne short blastOne flash34(a)(i) Altering to portTwo short blastsTwo flashes34(a)(ii) Operating engines asternThree short blastsThree flashes34(a)(iii) Narrow channel - overtake on stbdTwo prolonged + one shortn/a34(c)(i) Narrow channel - overtake on portTwo prolonged + two shortn/a34(c)(i) Narrow channel - agreementOne prolonged, one short, one prolonged, one shortn/a34(c)(ii) Doubt - in dangerFive or more short rapid blastsFive or more flashes34(d) Bend or obstructionOne prolonged blastn/a34(e)
In short
Sound and light signal pattern per COLREG Rule 34.