COLREG / ARPA / AIS Bridge Rule 18(a)(iii) 🔒 Course / Premium

Power-Driven Gives Way to Fishing Vessel (Rule 18(a)(iii))

Target is identified by AIS as a vessel ENGAGED IN FISHING (badge "F").

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Scenario briefing

Target is identified by AIS as a vessel ENGAGED IN FISHING (badge "F"). Rule 18(a)(iii): a power-driven vessel under way shall keep out of the way of a vessel engaged in fishing. Manoeuvre so that CPA 1 NM in open water.

Applicable COLREG rule(s)

Rule 18(a)(iii) — referenced in this scenario. Practising this scenario reinforces correct application under realistic time pressure.

📸 Bridge simulator scene

Captured directly from the SkipperCheck COLREG bridge simulator at scenario T = 0 — the moment the encounter begins.

SkipperCheck bridge simulator — COLREG Rule 18(a)(iii) — Power-driven gives way to fishing vessel — radar PPI with AIS targets — Bridge-simulator scene under COLREG Rule 18(a)(iii) — Power-driven gives way to fishing vessel. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.

Key teaching points

Rule 18(a)(iii): a power-driven vessel under way shall keep out of the way of a vessel engaged in fishing.
A vessel engaged in fishing shows the lights of Rule 26 — two all-round lights vertically, GREEN OVER WHITE (trawling) or RED OVER WHITE (other fishing methods).
A vessel engaged in fishing shall not impede the passage of any vessel in a narrow channel (Rule 9(c)) or a TSS lane (Rule 10(i)).
A vessel merely angling with rod-and-line is NOT "engaged in fishing" for Rule 18 purposes.

Common mistakes to avoid

Mistaking a sport-fishing yacht for a vessel "engaged in fishing". Only commercial gear (trawl, nets, lines) qualifies.
Crossing close astern of a trawler — the trawl extends 300–500 m behind. Pass well clear.

Why it matters

Vessels engaged in fishing are restricted in their ability to manoeuvre — nets, lines or trawls are deployed and the vessel cannot turn freely. Rule 18(a)(iii) gives them priority over power-driven vessels, and the rule is most often broken in approaches to fishing harbours where the priority is misread.

Exam relevance

Rule 18(a)(iii) paired with Rule 26 lights is a frequent night-time oral in Yachtmaster Coastal/Offshore and STCW OOW exams.

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