Study by Images
Browse each vessel type with fixed-aspect 3D models, matching 2D light diagrams, and day/night controls.
23Power-driven vessel underway
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An interactive 3D illustration is shown here. The same content is described in the rule text and key takeaways below.
2D light grid
Power-driven vessel ≥ 50 m
5 lights
Power-driven vessel < 50 m
4 lights
Power-driven vessel < 12 m — simplified
3 lights
Power-driven vessel < 7 m, max 7 kt (minimum)
1 lights
Air-cushion vessel, non-displacement mode
5 lights
WIG craft taking off, landing, or near surface
5 lights
How to learn vessel lights and day shapes with 3D models
Every vessel category in COLREG Part C — power-driven, sailing, towing, fishing, trawling, not under command, restricted in ability to manoeuvre, constrained by draught, pilot vessels, anchored and aground — carries a distinct combination of masthead, side, stern and all-round lights. This trainer shows each combination on an interactive 3D model, so you learn the pattern the way you would actually meet it at sea: from port, starboard, ahead and astern.
Switch between night view (lights only) and day view (shapes) for each vessel, and compare the 3D scene with the matching 2D diagram used in exam questions. The aspect you are shown — which lights are visible from which bearing — is exactly what PER, Yachtmaster and deck-officer papers test.
Once the patterns feel familiar, switch to the image-based test, where the same vessels appear unlabelled and you identify them by their lights alone.