COLREG / ARPA / AIS Bridge Rule 17(a)(i) Rule 8 🔒 Course / Premium

Crossing — You Are Stand-On (Rule 17(a)(i))

A power-driven vessel is on your PORT side, crossing right to left. You are the stand-on vessel. Rule 17(a)(i): keep your course and speed.

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Scenario briefing

A power-driven vessel is on your PORT side, crossing right to left. You are the stand-on vessel. Rule 17(a)(i): keep your course and speed. The other vessel is expected to give way. Monitor her action if she alters properly, you remain stand-on (no change). Click EVALUATE when clear.

Applicable COLREG rule(s)

Rule 17(a)(i) — referenced in this scenario. Practising this scenario reinforces correct application under realistic time pressure.

Rule 8 — 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 17(a)(i) — Crossing — you are stand-on — radar PPI with AIS targets — Bridge-simulator scene under COLREG Rule 17(a)(i) — Crossing — you are stand-on. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.

Key teaching points

Rule 17(a)(i): the stand-on vessel SHALL keep her course and speed.
Rule 17(a)(ii): once it is apparent the give-way vessel is not taking appropriate action, the stand-on vessel MAY take action.
Rule 17(c): the stand-on vessel taking action MUST NOT alter to port for a vessel on her own port side.
Monitor: bearing drift, AIS-reported turn or speed change, sound signals from the other vessel.

Common mistakes to avoid

Altering "to help" while still stand-on. Two ships both altering produces the canonical "dance of death".
Holding course past the point of no return. Rule 17(b) demands best-available action when collision cannot be avoided by give-way alone.

Why it matters

Stand-on is psychologically the hardest role under COLREG — the rule asks you to hold course and speed while another vessel closes. The discipline of trusting the rule, while still being ready to act under 17(a)(ii) and 17(b), is what examiners probe.

Exam relevance

Stand-on doctrine and the Rule 17(a)(ii) / 17(b) transitions are a standard probe in Yachtmaster Offshore and STCW OOW orals.

Related scenarios

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