COLREG / ARPA / AIS Bridge
Rule 25(b)
🔒 Course / Premium
Rule 25(b) - Sailing Tricolour < 20 m
NIGHT. A sailing vessel less than 20 m in length is approaching.
This scenario is part of the full library.
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Scenario briefing
NIGHT. A sailing vessel less than 20 m in length is approaching. She shows, at or near the top of the mast where it can best be seen, a SINGLE lantern combining RED (port arc), GREEN (starboard arc), and WHITE (stern arc) - no other lights are visible. What is this permitted configuration?
Applicable COLREG rule(s)
Rule 25(b) — referenced in this scenario. Practising this scenario reinforces correct application under realistic time pressure.
Why it matters
COLREG knowledge is the foundation of safe ship handling. Most maritime collisions happen because watchkeepers either misidentified the situation, applied the wrong rule, or acted too late. This scenario lets you train pattern recognition + correct response under time pressure — the exact skill the rules are designed to support. RYA, Yachtmaster, STCW and most national exams expect you to apply COLREGs reflexively, not just recite them.
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About SkipperCheck simulators
SkipperCheck offers two browser-based maritime training simulators:
- ARPA · AIS · COLREG Bridge Simulator — 54 scenarios covering Rules 2, 5–10, 12–19, 23–30, 34 and 35.
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