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See the rules of the water.

Lights, sound signals, rules, buoyage, charts, sailing, radio, and anchoring — made visual, interactive, and easy to revisit.

Free · No signup · Official sources cited · Progress stays on this device

Explore by topic

Every light configuration in rotatable 3D — day shapes included.

Hear every horn, bell, and gong signal — then identify them by ear.

Who gives way, in plain language, with the official text beside it.

IALA marks that actually blink — Region A and B.

Decode any charted light — Fl(2)WRG.10s — and watch it live.

What every mark on the chart means, drawn clean.

Points of sail and apparent wind, interactive.

Know what belongs on Channel 16, Channel 70, and a working channel.

Choose the spot, calculate scope, set the anchor, and verify it holds.

Drill any topic with instant feedback and explanations that link back to the visuals.

Instructors can deep-link any light, rule, or buoy straight into course notes and slides. Every fact cites its rule and official source.

Rule text comes from the public-domain USCG Navigation Rules; chart symbols follow NOAA U.S. Chart No. 1. Diagrams and questions are our own.

Color-vision-friendly modes, keyboard-friendly 3D with named viewpoints, and sound quizzes that are fully answerable visually.