The order of responsibility between vessels (Rule 18)

Navigation Rules, lights & bridges · Power & sail

Rule 18 sets who keeps out of whose way by vessel type. Power-driven vessels keep clear of vessels not under command, restricted in their ability to maneuver, engaged in fishing, or under sail. Sailing vessels keep clear of the first three. The overtaking, narrow-channel and traffic-lane rules come first.

The order

• A power-driven vessel underway keeps out of the way of a vessel not under command, a vessel restricted in her ability to maneuver, a vessel engaged in fishing, and a sailing vessel (Rule 18(a)).
• A sailing vessel underway keeps out of the way of a vessel not under command, one restricted in her ability to maneuver, and one engaged in fishing (Rule 18(b)).
• A vessel engaged in fishing keeps out of the way, so far as possible, of vessels not under command or restricted in their ability to maneuver (Rule 18(c)).
• COLREGS only: vessels other than those two avoid impeding a vessel constrained by her draft that shows the Rule 28 signals. The Inland Rules have no such category (COLREGS Rule 18(d); Inland Rule 18(d) is reserved).

When the order doesn't apply

• Rule 18 gives way to Rules 9, 10 and 13. A sailboat overtaking a powerboat must keep clear, and a sailboat or small boat must not impede a ship confined to a channel or following a traffic lane.
• Rule 18 is one of the in-sight rules (Rules 11-18), so it applies only when vessels can see each other. In fog, Rule 19 governs instead (Rules 11, 19(a)).

Who counts as what

• Any vessel driven by machinery is power-driven. A sailboat is a sailing vessel only while under sail with its engine not in use, so motorsailing counts as power-driven (Rule 3(b), (c)).
• 'Engaged in fishing' means using nets, lines, trawls or other gear that restricts maneuverability. A boat trolling with lines that don't restrict maneuvering isn't engaged in fishing (Rule 3(d)).
• 'Not under command' means unable to maneuver as the Rules require through some exceptional circumstance, such as a steering failure. 'Restricted in ability to maneuver' means limited by the work being done, such as dredging, buoy or cable work, or certain tows (Rule 3(f), (g)).

The rules: COLREGS Rule 3 · COLREGS Rule 18 · Inland Rule 18 · 33 CFR 83.03 · 33 CFR 83.18

A plain-language summary of federal rules for recreational boats, checked against the rules’ own text and a second source, and written in our own words. It isn’t legal advice. States add rules of their own, and rules change — the links above go to the current official text.