Navigation lights on a power boat

Navigation Rules, lights & bridges · Power boats

The Navigation Rules require a power-driven vessel underway from sunset to sunrise, and in restricted visibility, to show a masthead light, red and green sidelights and a white sternlight. Boats under 12 meters (39.4 ft) have a simpler option. Inland and International Rules are nearly the same here (Inland Rules 20, 23).

When the lights must be on

• Show your navigation lights from sunset to sunrise in all weathers, and also by day in fog, heavy rain or other restricted visibility. You may also show them at other times when you think it necessary (Inland Rule 20(b)-(c)).
• While they are lit, the rules forbid other lights that could be mistaken for navigation lights, make them harder to see or recognise, or interfere with keeping a proper lookout (Inland Rule 20(b)).
• 'Underway' means not anchored, not made fast to the shore and not aground, so a boat drifting with the engine off still needs her underway lights (Inland Rule 3(i)).

Under 12 meters (39.4 ft)

• You may show the full set (masthead light forward, sidelights and sternlight) or, instead, an all-round white light plus sidelights (Inland Rule 23(a), 23(d)).
• The masthead light, or the all-round white light, must be carried at least 1 meter [3.3 ft] higher than the sidelights (33 CFR 84.02(d)).
• On a boat this size the masthead light, and the sidelights if combined in one lantern, go as near the centreline as practicable (Inland Rule 21(a)-(b)).
• Seaward of the demarcation lines, the International Rules also let the all-round white light sit off the centreline when a centreline fitting isn't practicable, provided the combined sidelight lantern is on the centreline or in line with it (COLREGS Rule 23(d)(iii)).

12 meters (39.4 ft) to under 20 meters (65.6 ft)

• Show a masthead light forward, sidelights and a sternlight. A second, higher masthead light further aft is optional for any vessel under 50 meters (Inland Rule 23(a)).
• Below 20 meters the sidelights may be combined in one red/green lantern on the centreline (Inland Rule 21(b)).
• The masthead light must be at least 2.5 meters [8.2 ft] above the gunwale (33 CFR 84.02(c)). On Inland waters the sidelights must sit at least 1 meter lower than the forward masthead light (33 CFR 84.02(g)).
• A single masthead light goes forward of amidships; on a vessel under 20 meters, as far forward as practicable (33 CFR 84.03(d)).

Special cases

• On the Great Lakes a power-driven vessel may show an all-round white light, placed where the second masthead light would go, instead of the second masthead light and the sternlight (Inland Rule 23(e)).
• If your boat doesn't normally tow and towing lights are impracticable, you need not show them while towing a vessel in distress or needing help. You must still take all possible measures to show that the two boats are connected, and may light the tow with a searchlight (Inland Rule 24(i)).

The rules: Inland Rule 3 · Inland Rule 20 · Inland Rule 21 · Inland Rule 22 · Inland Rule 23 · Inland Rule 24 · COLREGS Rule 23 · 33 CFR 84.02 · 33 CFR 84.03 · 33 CFR 84.20

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.