COLREGs lights and shapes for your skipper exam. International Regulations for Preventing Collisions at Sea
Learn to read the night horizon like a road sign. Free flashcards for Rules 20 to 29, except Rule 24 (towing). Each card comes back on a spaced-repetition schedule until you answer without thinking.
Free · no install · works on your phone in the marina
At night you see both sidelights of a vessel together, under her masthead light. What does that tell you?
Pick an answer — it's a real card.
THE DECK
The lights-and-shapes rules, one module at a time.
66 cards in 4 modules, every answer checked against the International rule text. Each round mixes cards from all of them.
Lights Basics
When the lights and shapes rules apply, what each navigation light is and shows, and how far it must be seen — COLREGs Rules 20–22.
SAMPLE CARD Which colour does each sidelight show?
Power-Driven and Sailing Vessels
Lights of power-driven vessels underway, air-cushion and WIG craft, small craft, sailing vessels and vessels under oars — COLREGs Rules 23 and 25.
SAMPLE CARD How do a sailing vessel's lights underway differ from those of a power-driven vessel underway?
Fishing and Pilot Vessels
Trawlers and other fishing vessels, outlying gear, fishing on and off the grounds, and pilot vessels on and off duty — COLREGs Rules 26 and 29.
SAMPLE CARD Which vessel shows two all-round lights, white over red, at or near the masthead?
Not Under Command, Restricted, Constrained
Vessels not under command, restricted in their ability to maneuver, dredging, diving, clearing mines or constrained by their draft — COLREGs Rules 27 and 28.
SAMPLE CARD What does a vessel restricted in her ability to maneuver hoist by day, where it can best be seen?
RECOGNISE, DON'T RECALL
At sea you get two seconds. Train for that.
Shapes and lights are shown, not described. Tap one to check yourself.
HOW IT WORKS
Ten minutes a day until exam day.
Spaced repetition brings each card back right before you’d forget it. Easy cards fade back, the ones you miss come round again soon.
Open the deck
Each round mixes cards from all the modules, so lights basics and vessel signals come up side by side.
Answer the card
Questions written from the rule text, with the rule reference and an explanation every time.
Come back tomorrow
The schedule decides which cards come back, and when. A few minutes and you’re done.
FAQ
Before you cast off.
The lights and shapes of the International COLREGs, Rules 20 to 29 except Rule 24: when lights and shapes apply, what each light is, and what power-driven, sailing, fishing, pilot, not-under-command, restricted and draft-constrained vessels show. Towing and pushing (Rule 24), anchored and aground vessels (Rule 30), steering and sailing rules, sound signals, buoyage and the U.S. Inland rules are not covered yet. Your national authority sets your exam’s syllabus, so check it there.
Your first card is the next one you'll see at sea.
Free, in the browser, no account needed to start.
Start COLREG prep →Study aid only — always carry the official COLREG text on board.