Rules of the Road · Sound Equipment

Annex III of the COLREGS governs technical details of sound signal appliances. According to that annex, what determines the required frequency and audibility range of a vessel's whistle?

Explanation

Annex III Section 1 links whistle frequency and audibility to vessel length. Larger vessels require lower fundamental frequencies (more penetrating in fog) and greater audibility ranges. A vessel 200 meters or more requires a range of 2 nautical miles; a vessel under 20 meters requires only 0.5 nm. Length is the governing parameter.

Authority: 72 COLREGS Annex III, Section 1

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