🔍 Key Concepts

• Sound signals in restricted visibility (fog signals) for vessels underway and at anchor • Special fog signal patterns for vessels not under command (NUC), restricted in ability to maneuver (RAM), constrained by draft, and sailing vessels • Which vessel types have identical signals in both conditions (underway vs. at anchor)

💭 Think About

• First recall the standard fog signal for a power-driven vessel underway making way and compare it to what special vessels must sound when underway. • Then think about how the fog signal changes (or not) when those same vessels are at anchor. • Ask yourself: which of these four vessel types does not change its fog signal pattern between underway and at anchor?

✅ Before You Answer

• Verify in the Navigation Rules, Annex III / Part D on Sound and Light Signals in Restricted Visibility which vessel(s) have the same pattern for both conditions. • Check carefully whether anchor status adds any extra bell, gong, or rapid ringing to the signal for each special vessel type. • Confirm which of these vessels has no additional anchor-only signal beyond what it already sounds underway.