COLREG / ARPA / AIS Bridge Rule 2(a) Rule 2(b) Rule 17(c) 🔒 Course / Premium

Rule 2 — Departure to Avoid Immediate Danger

DILEMMA: Clear visibility. You are the STAND-ON vessel in a crossing situation a power-driven give-way vessel is on your PORT side and has failed to act.

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Scenario briefing

DILEMMA: Clear visibility. You are the STAND-ON vessel in a crossing situation a power-driven give-way vessel is on your PORT side and has failed to act. Rule 17(c) forbids altering course to PORT for a vessel on your own port side. However, shoal water lies immediately to STARBOARD a starboard turn would put you aground. Which response best complies with COLREG 72?

Applicable COLREG rule(s)

Rule 2(a) — referenced in this scenario. Practising this scenario reinforces correct application under realistic time pressure.

Rule 2(b) — referenced in this scenario. Practising this scenario reinforces correct application under realistic time pressure.

Rule 17(c) — 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 2 — Departure to avoid immediate danger — radar PPI with AIS targets — Bridge-simulator scene under COLREG Rule 2 — Departure to avoid immediate danger. Captured from the SkipperCheck COLREG / ARPA / AIS bridge simulator.

Key teaching points

Rule 2(a) — nothing exonerates a vessel from following the ordinary practice of seamen.
Rule 2(b) — special circumstances (proximity of danger, vessel limitations) may require a departure from the Rules to avoid immediate danger.
A Rule 2 departure must be a positive choice supported by reasoning, not an excuse for not knowing the right rule.
Document the reasoning in your logbook — courts and inquiries expect to see WHY you departed from a numbered rule.

Common mistakes to avoid

Invoking Rule 2 to justify failure to keep a proper look-out or to act in good time. Rule 2 does not excuse negligence.
Departing from another rule without first establishing that "ordinary practice" demands it.

Why it matters

Rule 2 is the rule that empowers — and obliges — you to depart from any other rule when the ordinary practice of seamen makes it necessary. The "Rule 2 dilemma" is the moment when blindly following the letter of another rule would cause the very collision the rules exist to prevent.

Exam relevance

Rule 2 dilemma scenarios appear in STCW OOW orals and in RYA Yachtmaster Offshore — the candidate must justify departure from another rule using Rule 2(b) language.

Related scenarios

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