Sound Signal Player
audioRequired for vessels ≥ 12 m
Whistle
0:00 / 0:05
Whistle
Bell
Gong
Part DIntermediate
Rule 33: Equipment for sound signals
Required sound equipment scales with vessel length, with audibility and manual-use requirements.
Detailed Explanation
(a) Equipment by length: vessel ≥12 m must carry whistle; ≥20 m whistle + bell; ≥100 m whistle + bell + gong (gong tone must be distinguishable from bell). All must comply with Annex III. Bell/gong may be replaced by equivalent equipment, but manual sounding of required signals must always be possible.
(b) Vessel <12 m need not carry prescribed appliances, but must have another efficient means of sound signalling.
Key Points
- ≥12m: whistle + bell required
- ≥100m: whistle + bell + gong required
- <12m: any efficient sound signal device
- Audibility standards set by vessel length
Examples
- Your 25 m fishing vessel must carry a whistle and a bell per Rule 33(a). The bell is required because the vessel is 20 m or over in length.
- A 120 m tanker must carry a whistle, a bell in the forepart, and a gong in the after part. Rule 33(a) requires the gong for vessels 100 m or more in length.
- An 8 m dinghy has no whistle, only a handheld air horn. Rule 33(b) says vessels under 12 m need not carry prescribed sound-signalling appliances but must have some means of making an efficient sound signal.
Common Mistakes
- Not carrying a bell on a vessel of 20 metres or more, or carrying one that does not meet audibility requirements.
- Forgetting that vessels of 100 metres or more must also carry a gong in addition to the bell.
- Using a substitute device on a vessel under 12 metres without ensuring it produces an efficient sound signal.