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

Power-Driven Gives Way to Vessel RAM (Rule 18(a)(ii))

The AIS target reports "Restricted Ability to Manoeuvre" (RAM) e.g. a cable-layer or dredger (badge "R").

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Scenario briefing

The AIS target reports "Restricted Ability to Manoeuvre" (RAM) e.g. a cable-layer or dredger (badge "R"). Rule 18(a)(ii): a power-driven vessel shall keep out of the way of a vessel restricted in her ability to manoeuvre. Give way early.

Applicable COLREG rule(s)

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

Key teaching points

Rule 18(a)(ii): a power-driven vessel under way shall keep out of the way of a vessel restricted in her ability to manoeuvre.
A RAM shows three all-round lights vertically — RED OVER WHITE OVER RED (Rule 27(b)(i)).
When making way, she also shows the normal masthead, sidelights and sternlight.
Pass well clear on whichever side is shown to be safe — a RAM laying cable will indicate the safe side with red/red and green/green light groups.

Common mistakes to avoid

Confusing RAM (red-white-red) with NUC (red-red) — different lights, different priorities under Rule 27.
Crossing too close to a cable-layer "because she's slow" — the cable on the bottom is the hazard, not the ship.

Why it matters

A vessel restricted in her ability to manoeuvre (RAM) is doing work that physically prevents normal navigation — laying cable, dredging, transferring stores at sea, lifting helicopters. Rule 18(a)(ii) gives her near-absolute priority and the lights (Rule 27) make her instantly recognisable.

Exam relevance

Rule 27 RAM lights and Rule 18(a)(ii) priority are a standard light-recognition oral in STCW OOW and Yachtmaster Offshore exams.

Related scenarios

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