What the collision regulations part covers
Shorebased theory courses such as RYA Day Skipper devote one part to the collision regulations, and it comes down to three skills: recognise a vessel by her lights at night, read her day shapes (ball, cone, diamond, cylinder), and match a sound signal to the manoeuvre. On top of that the exam expects the give-way order: who keeps out of the way and who keeps course and speed.
Where to learn each part
- Lights and shapes: 35 configurations from ahead, from the beam and from astern, plus the vessel in 3D with the 112.5 and 135 degree sector limits marked.
- Sound signals: 20 signals synthesised in the browser, nothing to download.
- All 38 rules: plain wording, an example at sea, and the verbatim text.
- 118 flashcards: decks for lights, shapes and sound signals, with a multiple-choice Check mode and a 20-question Exam mode.
Three things people get wrong
- The sectors. A sidelight covers 112.5 degrees and ends 22.5 degrees abaft the beam; past that you see only her sternlight, 135 degrees. Masthead light: 225. Drag the slider in the 3D vessel and watch the green go out.
- Nobody has right of way. One vessel keeps out of the way, the other keeps her course: the order is in Rule 18, and an overtaking vessel (Rule 13) keeps clear whatever type she is.
- Restricted visibility. In fog there is no give-way vessel at all: Rule 19 applies, not the Rule 18 order. The Situations mode drills exactly this difference.
The official text: IMO, Convention on the International Regulations for Preventing Collisions at Sea
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Source, method, updated: 07.09.2026