🔍 Key Concepts

• Sound signals in restricted visibility under Rule 35 of the Navigation Rules • Difference between distress signals (Annex IV) and normal sound signals • Special signals for vessels that are aground or anchored in fog

💭 Think About

• Ask yourself: In fog, what sound signal patterns are used by vessels that are simply underway, but may not necessarily be in an emergency? • Consider: Does a continuous sounding of the fog whistle match any of the official distress signals listed in the Navigation Rules? • Think about whether pilots or radio communication requests are normally indicated by fog signals or by some other means (lights, flags, or radio itself).

✅ Before You Answer

• Check Rule 35 to see what sound signals are prescribed for vessels underway in or near an area of restricted visibility. • Verify in Annex IV which specific patterns are listed as distress signals and see if a continuous fog whistle is one of them. • Confirm what additional signals (if any) are specified for a vessel aground, and whether they involve a continuous fog whistle or a different pattern.