The short answer. A power boat under 12 meters (39.4 ft) needs red and green sidelights plus either a masthead light and a sternlight, or one all-round white light. Sailboats under sail show sidelights and a sternlight, or one tricolor at the masthead if under 20 meters. At anchor, one all-round white light covers any boat under 50 meters.
This is a plain summary of the Rules, not legal advice. Check the Rules for your boat’s length and type.
You’ll need
- Red and green sidelights, as two lights or one bi-color bow light
- A white light aft: a sternlight with a masthead light, or a single all-round white light (power boats under 12 meters)
- An all-round white light for anchoring, which on most small boats is that same light: Perko fold-down masthead/all-round light 1184, Perko Stealth LED fold-down all-round light, vertical mount 1639, Perko Stealth LED tower/arch all-round light 1609
- A switch that turns the anchor light on alone, with the sidelights off
The rules read heavy, but for most small boats they come down to a handful of lights. Two things set yours: the boat’s length, and what’s moving it right now.
The USCG Navigation Rules are the ones that count: the Inland Rules (33 CFR Part 83) inside the demarcation lines, the International Rules outside. Rule numbers match, and the few small-boat differences are flagged below. Read on, then check your own boat with the steps further down.
What do the light names mean?
Rule 21 defines each light by the arc it covers, measured around the horizon:
- Masthead light: white, facing forward, showing over 225 degrees, from dead ahead to 22.5 degrees behind the beam on each side.
- Sidelights: green on the starboard side, red on port, each covering 112.5 degrees. Boats under 20 meters can combine the two in one lantern (the bi-color bow light).
- Sternlight: white, at the stern, covering the 135 degrees behind.
- All-round light: one light that shows all 360 degrees.
When do navigation lights have to be on?
Rule 20 says from sunset to sunrise, in any weather. They also go on in daytime when visibility is restricted (fog, heavy rain, snow), if your boat has them. Between sunset and sunrise, no other light may be on if it could be mistaken for a nav light or makes yours harder to see. Deck lights, cockpit lights and light bars all count.
Which lights does a power boat need?
Rule 23(a) sets the full set for a power-driven boat underway: a masthead light forward, sidelights and a sternlight. A second, higher masthead light aft is required only at 50 meters and up.
Under 12 meters, Rule 23(d) gives you a shorter option: one all-round white light plus sidelights, in place of the masthead light and sternlight. That’s the pole light you see at the back of a lot of runabouts, center consoles and pontoons.
Annex I adds a height rule (33 CFR 84.02). On a power boat under 12 meters, the masthead light or that all-round white light has to sit at least 1 meter (about 3.3 ft) higher than the sidelights. From 12 meters to under 20 meters, the masthead light sits at least 2.5 meters (about 8.2 ft) above the gunwale.
The International Rules add two small-boat options:
- Under 7 meters (about 23 ft) with a top speed of no more than 7 knots, a power boat may show just an all-round white light, plus sidelights if that’s practical (Rule 23(d)(ii)).
- Under 12 meters, if the white light can’t go on the centerline, it may sit off to the side. The sidelights then have to be one combined lantern on the centerline or in line with the white light (Rule 23(d)(iii)).
On Inland waters, neither of those is in Rule 23. Under 12 meters there, Rule 21 only says the masthead light and a combined lantern go as near the centerline as practicable.
Which lights does a sailboat need?
Under sail, Rule 25 asks for sidelights and a sternlight. No masthead light. On a sailboat under 20 meters, all three can be combined in one tricolor lantern at or near the top of the mast.
Red-over-green all-round lights at the masthead are optional with sidelights and a sternlight, never with the tricolor.
Under 7 meters, a sailboat shows those lights if it practically can. If it can’t, it shows an all-round white light or keeps a white flashlight or lit lantern at hand, ready to show in time to prevent a collision.
When the engine is running, you’re a power boat. Rule 3 makes any boat propelled by machinery power-driven, and a sailboat counts as a sailing vessel only while the engine isn’t being used. Under motor, sails up or not, the tricolor goes off and the power-boat lights go on.
What about rowboats and kayaks?
Rule 25 lets a vessel under oars show the same lights as a sailboat. If it doesn’t, it needs an all-round white light, or a white flashlight or lit lantern at hand to show in time to prevent a collision. The Rules call this “under oars,” so a canoe or kayak owner should read Rule 25 for themselves.
Which light do I show at anchor?
Rule 30 asks for an all-round white light forward and a second, lower one at the stern. Boats under 50 meters can show a single all-round white light where it can best be seen instead. On most small boats that’s the same pole light you run with, switched on with the sidelights off.
Two exemptions:
- Under 7 meters: no anchor light is required when you’re anchored away from a narrow channel, fairway or anchorage, and away from where other boats normally run (Rule 30(e)).
- Inland only, under 20 meters: no anchor light is required in a special anchorage area designated by the Coast Guard (Rule 30(g)). The International Rules don’t have this one.
Quick table: boat type and length to lights required
| Your boat | Underway | At anchor | Rules |
|---|---|---|---|
| Power, under 7 m (about 23 ft), top speed 7 knots or less, International waters | All-round white, plus sidelights if practical; or the under-12 m options | One all-round white (none if away from channels and traffic) | Intl 23(d)(ii), 30(b), 30(e) |
| Power, under 12 m (39.4 ft) | Sidelights + all-round white, or sidelights + masthead + sternlight. White light 1 m above the sidelights. | One all-round white | 23(a), 23(d), 30(b), Annex I 84.02(d) |
| Power, 12 m to under 20 m (39.4 to 65.6 ft) | Masthead + sidelights + sternlight. Masthead 2.5 m above the gunwale. | One all-round white | 23(a), 30(b), Annex I 84.02(c) |
| Sail under sail, under 7 m | Sidelights + sternlight or tricolor, if practical; if not, all-round white or a white flashlight ready | One all-round white (none if away from channels and traffic) | 25(d)(i), 30(b), 30(e) |
| Sail under sail, under 20 m | Sidelights + sternlight, or one tricolor at the masthead | One all-round white | 25(a), 25(b), 30(b) |
| Sailboat motoring (sails up or down) | Power-boat lights for its length | One all-round white | 3(b), 3(c), 23 |
| Rowboat (under oars) | Sailboat lights, or all-round white or a white flashlight ready | One all-round white (none under 7 m away from channels and traffic) | 25(d)(ii), 30 |
| Any boat under 20 m in a Coast Guard special anchorage (Inland only) | (as above) | None required | Inland 30(g) |
How far do the lights have to be seen?
Rule 22 sets a minimum range for each light. The Rules write it in miles; light makers usually write nm.
| Light | Under 12 m | 12 m to under 20 m | 20 m to under 50 m |
|---|---|---|---|
| Masthead | 2 | 3 | 5 |
| Sidelight | 1 | 2 | 2 |
| Sternlight | 2 | 2 | 2 |
| All-round white | 2 | 2 | 2 |
So a light certified to 2 nm covers an all-round white on any boat under 50 meters. It also covers a masthead light under 12 meters. Between 12 and 20 meters, the masthead light needs 3 nm.
When you shop, check the light’s USCG certification range and the boat length the maker certifies it for. Perko prints both on each product page.
How do I check my boat’s lights? Step by step
You can check your whole setup in one evening at the dock. Here’s how.
- Know your length. Use the boat’s length in meters, or the feet shown next to each meter figure on this page.
- Know your waters. Inland or International. Most of the rules match; the differences are flagged above.
- Find your row. Look up your boat type and length in the quick table, for underway and at anchor.
- Check the colors and sides. Green on starboard, red on port, white where your row says.
- Check the height. On a power boat, compare your white light’s height with the Annex I rule in the power boat section.
- Check the range. Read the USCG certification range on each light (or its maker’s page) against the visibility table.
- Test the anchor setting. All-round white on, sidelights off. If one switch can’t do that, plan a switch change.
- Look at them lit. At dusk, switch on and walk around the boat from the dock. Check each light shows on its side and nothing else on deck outshines it.
Anything missing or dim? Swap it now, before your next night run.
Picking the white light
Most boats under 12 meters with an all-round pole light are swapping one of three kinds:
- Fold-down pole lights lie flat for covers and low bridges: the 14 inch Perko fold-down masthead/all-round light 1184 (bulbs, 3 nm) or the LED Perko Stealth LED fold-down all-round light, vertical mount 1639 (2 nm).
- Plug-in poles come out when you don’t need them: Perko plug-in masthead/all-round light 22 in 1124.
- Short lights go high on a hardtop or arch: the 4 inch Perko fixed-mount masthead/all-round light 1183, or the Perko Stealth LED tower/arch all-round light 1609, which folds down into a cockpit courtesy light. Under 12 meters, it still has to clear the sidelights by 1 meter.
LED matters for the battery. Perko lists 0.80 amps per compartment for the 1184 and 0.1 amps for the Stealth lights. Anchor lights burn all night, so that difference adds up. Boat LED lighting amp draw: what your lights cost the battery runs the numbers, and Fold-down all-round and anchor lights: how to pick one compares mounts and heights.
Does this guide fit your boat?
This applies if: – Your boat is under 20 meters (65.6 ft): a power boat, sailboat or rowboat. – You run US Inland waters or International waters under the USCG Rules. – You’re replacing a light or checking what your boat should show.
This doesn’t apply if: – Your boat is 20 meters or longer, is fishing with gear that restricts how it moves, is towing, or is not under command. Rules 24 and 26 to 29 add lights for those. – You run the Great Lakes. Inland Rule 23(e) has a different white-light option there. – You need a ruling on your own boat. Ask the Coast Guard or a marine surveyor.
Products in this guide
| Product | Why it’s here |
|---|---|
| Perko fold-down masthead/all-round light 1184 | Fold-down pole, two compartments, USCG 3 nm, sail or power under 20 m |
| Perko plug-in masthead/all-round light 22 in 1124 | Plug-in pole, 22 inch, masthead and anchor compartments, USCG 3 nm |
| Perko fixed-mount masthead/all-round light 1183 | 4 inch fixed light for a hardtop or arch, USCG 3 nm |
| Perko Stealth LED fold-down all-round light, vertical mount 1639 | LED all-round, 0.1 A, USCG 2 nm, power under 20 m |
| Perko Stealth LED tower/arch all-round light 1609 | LED all-round for 7/8 inch tubing, folds down to a courtesy light |
Prices show live from the store. None of the sidelights or tricolors we looked at made this list, so you’ll need those from elsewhere for now. Other lights we carry are in Navigation lights.
Bundles for this job: Nav light refit kit
Quick answers
Do I need navigation lights during the day? Only in restricted visibility. Rule 20 says lights you carry also go on from sunrise to sunset in fog, heavy rain or similar conditions.
Can my all-round white light double as my anchor light? Yes, on a boat under 50 meters. Rule 30(b) allows one all-round white light at anchor. Turn the sidelights off so you don’t look like a boat underway.
Is a 2-mile light good enough? For an all-round white light, yes, on any boat under 50 meters (Rule 22). For a masthead light on a boat from 12 to 20 meters, no: that needs 3 miles.
Sources
- 33 CFR Part 83 (Inland Navigation Rules), Rules 3, 20, 21, 22, 23, 25 and 30: https://www.ecfr.gov/current/title-33/chapter-I/subchapter-E/part-83
- 33 CFR 84.02 (Annex I, positioning of lights): https://www.ecfr.gov/current/title-33/chapter-I/subchapter-E/part-84/section-84.02
- USCG NAVCEN, Navigation Rules (International and Inland side by side): https://www.navcen.uscg.gov/navigation-rules-amalgamated
- Perko Fig. 1184: https://www.perko.com/catalog/navigation_lights_under_20_meters/837/combination_masthead_and_white_all-round_anchor_light/
- Perko Fig. 1183: https://www.perko.com/catalog/navigation_lights_under_20_meters/131/fixed_mount_combination_masthead___white_all-round_light/
- Perko Figs. 1123/1124: https://www.perko.com/catalog/navigation_lights_under_20_meters/121/combination_masthead_and_white_all-round_light/
- Perko Fig. 1639: https://www.perko.com/catalog/navigation_lights_under_20_meters/815/stealth_series_-_led_fold_down_white_all-round_light/
- Perko Fig. 1609: https://www.perko.com/catalog/navigation_lights_under_20_meters/817/stealth_series_-_tower_arch_mount_led_folding_white_all-round_light/
