The International Regulations for Preventing Collisions at Sea (COLREGS, also known as IRPCS or Rules of the Road) govern how vessels behave when in sight of each other. Mastery of the 72 rules is required for every USCG license exam and is tested on every STCW-related certification.
What COLREGS covers
The rules are organized into five parts and several annexes. The most frequently tested sections in our game include:
- Part B — Steering and Sailing Rules — Right-of-way hierarchy, crossing, head-on, and overtaking situations
- Part C — Lights and Shapes — Which lights a vessel displays at night, what shapes it shows by day
- Part D — Sound and Light Signals — Whistle signals, distress signals, fog signals
- Rule 5 — Lookout duties
- Rule 8 — Action to avoid collision
How to study effectively
The most efficient path through COLREGS is spaced repetition. Focus first on Part B (the steering and sailing rules), then Part C (lights and shapes), then audio signals. The game presents scenarios and explains the correct rule after each question, so you learn from mistakes without having to flip to a textbook.
For the USCG exam, expect 10–15 COLREGS questions on a 100-question exam at the Mate 500 GRT level. At Master level, the proportion is higher. Practice daily for two weeks and most exam-takers find COLREGS becomes their strongest topic.