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33

Equipment for Sound Signals

Vessels 12m+ must carry a whistle and bell. Vessels 100m+ must also carry a gong.

Rule 33 specifies required sound signal equipment.

a
A vessel of 12 metres or more in length shall be provided with a whistle and a bell.
b
A vessel of 100 metres or more in length shall, in addition, be provided with a gong.
c
Vessels less than 12 metres are not obliged to carry these but must have some means of making an efficient sound signal.

Signal Workflow

1

Decide the context first: manoeuvring in sight, restricted visibility, or distress. The same whistle can mean very different things in a different context.

2

Check both the pattern and the interval. For fog signals, the time spacing is part of the rule, not just the blast sequence.

3

When in doubt about another vessel's intentions, use the prescribed warning signal early rather than waiting for the situation to deteriorate.

Exam Focus

1

Three short blasts are astern propulsion, not a fog signal.

2

In restricted visibility, think 'every two minutes' for underway signals and 'every one minute' for anchor bell signals.

Key Takeaways

1

12m+: whistle and bell required

2

100m+: whistle, bell, AND gong required

3

Under 12m: some means of sound signal required

4

Equipment must meet technical specifications in Annex III

Common Mistakes

Not carrying a gong on vessels 100m or more

Small vessels having no means of making sound signals at all

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