Collision Regulations and Navigation Rules
The framework
Collision regulations exist to prevent collisions at sea. The candidate must know the concepts of keeping a proper lookout, safe speed, and risk of collision, plus the hierarchy of responsibility: everyone must act to avoid collision even if they hold right of way. Learn the power-driven versus sailing vessel hierarchy, and the special status of vessels not under command, restricted in ability to manoeuvre, fishing vessels and vessels constrained by draft.
Meeting, crossing and overtaking
Head-on: both alter course to starboard and pass port-to-port. Crossing: the vessel with the other on its starboard side gives way; the stand-on vessel keeps course and speed but must act if collision is imminent. Overtaking: the overtaking vessel keeps clear regardless of propulsion type. Know the meaning of the sector lights and shapes conceptually: a vessel showing a red light to you is seeing your green, and you should give way if it is on your starboard side.
Traps
Questions often test the stand-on vessel's duty (it is not 'do nothing'), the fact that a sailing vessel does not always have right of way (a power vessel overtaking a sailboat still keeps clear), and narrow channel rules. Watch for wording such as 'first action'.
Worked example
You are in a powerboat and see another powerboat fine on your starboard bow, bearing steady and range decreasing. Risk of collision exists, so you are the give-way vessel: alter course to starboard, pass astern of the other vessel, and avoid crossing ahead.