Marine LED lights
Navigation light arcs and colors, waterproofing, corrosion, 12 and 24 V power, underwater, dock and trailer lights
Navigation lights are the colored lights a vessel must show between sunset and sunrise so others can tell its heading and type. Their colors, arcs and minimum visible ranges are fixed by the international collision regulations (COLREGs). LED versions must still match those arcs and colors, not just be bright.
Boats are hard on lighting: salt spray, vibration, constant damp and a battery bank that has to last the night. LEDs fit the job because they draw a fraction of the current of a halogen or incandescent bulb and last far longer, but a waterproof-looking lamp is only useful on a boat if it meets the navigation rules and survives corrosion. This guide expands the short marine section on the applications page with the arcs, ratings, wiring and the lights beyond navigation.
What arcs and colors do navigation lights show?
A powered vessel under way shows a white masthead light over a 225° arc ahead, a red port and a green starboard sidelight each covering 112.5°, and a white sternlight over 135°. Together they cover a full circle. At anchor a vessel shows an all-round white light instead.
The arcs are set by COLREGs Rule 21. The masthead light and both sidelights start dead ahead and end 22.5° abaft the beam on each side, so the masthead light covers 112.5° per side and each sidelight covers 112.5° on its own side. The sternlight fills the remaining 135° astern. An observer sees red only from the port bow, green only from the starboard bow, white from behind, and both colors together when a vessel is coming straight at them. Rule 22 sets the minimum visible range, which depends on length.
| Light | Color | Arc | 12–50 m vessel | Under 12 m |
|---|---|---|---|---|
| Masthead | White | 225° | 5 nm (3 nm under 20 m) | 2 nm |
| Sidelights | Red (port), green (starboard) | 112.5° each | 2 nm | 1 nm |
| Sternlight | White | 135° | 2 nm | 2 nm |
| All-round (anchor) | White | 360° | 2 nm | 2 nm |
Small vessels have options. Powered boats under 12 m may show a single all-round white light plus sidelights in place of separate masthead and sternlights, and a boat under 7 m traveling no faster than 7 knots may show just an all-round white light. A sailing vessel under 20 m may combine its three lights in a tricolor at the masthead. Sailing vessels under about 7 m with no lights fitted must have a torch ready. Inland rules in the US and rules on some lakes and rivers differ in details, so check which apply where you boat.
COLREGs navigation light arcs (top view)
An LED light must also hit the right color: the red and green chromaticity limits in the regulations are strict, and a cheap LED that is merely "red" or "green" may fall outside them. Buy lights that state compliance with the Navigation Rules for your boat's length, with certification by the Coast Guard or your national authority where required, and mount them so that nothing on the boat blocks the arc. The ABYC A-16 standard covers electric navigation lights in the US. LED drivers can also produce radio noise, so check for low-RFI drivers if VHF reception matters.
How waterproof and corrosion-resistant should marine LEDs be?
Choose IP67 as the minimum for deck, mast and cabin-exterior lights, and IP68 for lights that sit below the waterline or are often submerged. Waterproofing is only half the job: salt corrodes metal, so look for 316 stainless or anodized housings, potted electronics and tinned copper wire.
An IP67 light survives temporary immersion up to 1 m, while IP68 is rated for continuous immersion under conditions the maker states, so check the depth and duration on the datasheet (the IP ratings table explains every code). Salt is the real enemy. It attacks unprotected aluminum, plated brass and copper, creeps along wire strands by capillary action and bridges dissimilar metals, which causes galvanic corrosion. Reliable marine fixtures use 316 stainless, bronze, anodized or powder-coated marine-grade aluminum, silicone or polycarbonate lenses and potted drivers. Wire should be tinned copper, with adhesive-lined heat-shrink or sealed connectors, and connections should be above the bilge. Makers often cite salt-spray tests (ASTM B117 or IEC 60068-2-52) for hundreds of hours, but check that the test covers the whole fixture, not only the finish.
Do marine LEDs run on 12 V or 24 V, and how much current do they use?
Most boats have a 12 V DC system, and larger or commercial vessels use 24 V. Quality marine LEDs include a constant-current driver that accepts about 9–32 V, so one light suits both. A typical LED navigation light draws roughly 0.1–0.5 A, against 1–2 A for the incandescent bulb it replaces.
Battery voltage is not steady: a 12 V system rests near 12.6 V, rises to 13.8–14.4 V while charging and falls below 12 V as the battery empties, so a driver that regulates current keeps brightness constant. Voltage drop in long cable runs to the masthead or bow is the most common cause of dim lights, and ABYC allows only 3% drop for navigation lights, against 10% for non-critical loads. Size the wire for length and current (the wire-gauge notes apply the same arithmetic), fuse each circuit at its source and use tinned copper. For LED strip on a boat, see which voltage to choose, and use IP67 or IP68 strip.
What are underwater, dock and courtesy lights for?
Underwater lights, usually fitted to the transom or the drain plug, light the water for swimming, fishing and appearance, and blue or green penetrates farthest. Dock lights are low-voltage lights for safe footing. Courtesy and cabin lights use red to protect night vision, and deck floods light work areas.
Water absorbs red light within a few meters and passes blue and green farthest, which is why underwater boat lights are blue, green or white. They must be IP68, and any light mounted through the hull needs a proper through-hull fitting. Dock lights should be low-voltage (typically 12 V) with sealed cable. In marinas, faulty AC wiring can leak current into the water and cause electric shock drowning, so keep dock lighting on a protected, correctly wired system. Cabin, cockpit and step lights benefit from a red mode because red light barely affects the dark-adapted eye, so a helm remains readable and the crew keeps their night vision. Deck floods and spreader lights should be aimed down and kept off while under way, because glare can hide the navigation lights of other vessels and ruin the helmsman's night vision.
What should a boat trailer's LED lights be?
Boat trailers get dunked at every launch, so use sealed LED lights rated IP68 and submersible, with potted wiring and no replaceable bulb sockets. Most trailer failures come from corroded grounds and plugs, not the lamps, so give each light its own ground and unplug the connector before launching.
An LED trailer light has no filament to crack when a hot lamp meets cold water, and it draws a fraction of the current, which also helps a tow vehicle's wiring. The lamps themselves still need to carry the DOT or SAE markings required where you drive. Disconnect the plug before backing in, fit dielectric grease in the connector, run a dedicated white ground wire to the frame in addition to the one in the plug, and rinse salt off the lights and connector after each outing.
Frequently asked questions
Can I replace my boat's halogen navigation light with an LED?
Yes, if the LED unit is certified as meeting the navigation rules for your boat's size. A retrofit bulb in an old fixture often changes the arc, because the lens was built around a filament, so a complete certified LED light is safer.
What is the difference between IP67 and IP68 for boat lights?
IP67 means dust-tight and tested for temporary immersion up to 1 m for 30 minutes. IP68 means continuous immersion under conditions the maker states. Use IP67 above the waterline and IP68 for underwater and trailer lights.
Do LED lights interfere with marine radio?
Some do. Cheap LED drivers switch at high frequency and can add noise that is heard on VHF and AM receivers. Choose lights sold as low-RFI, keep cables away from antenna leads and test reception with the lights on.
Why is red light used on boats at night?
Red light has little effect on the dark-adapted eye, so a helmsman reading a chart or instrument keeps the ability to see unlit objects on the water. A white light, even a dim one, resets night adaptation for several minutes.
Are underwater boat lights legal?
Rules vary by state and country. Most allow them when the boat is stationary or at the dock but restrict colors such as flashing blue and red, and some bar them when under way. Check your local boating regulations.
Can I use a 12 V LED strip on a boat?
Yes, if it is rated for the environment: IP67 or IP68 silicone-encased strip, tinned wiring and sealed connections. Strips for dry indoor use corrode quickly in a humid cabin, so mount them in channels and use marine-rated power connections.
Do I need navigation lights on a kayak or small dinghy?
Rules vary by country and size, but small human-powered boats under 7 m generally need a white light, often a handheld torch or all-round light, shown in time to prevent a collision. Check your local requirements before paddling after dark.
Sources and further reading
- International Maritime Organization, Convention on the International Regulations for Preventing Collisions at Sea (COLREGs 1972), Rules 20 to 25 and 30, and Annex I (positioning and technical details of lights).
- U.S. Coast Guard, Navigation Rules: International-Inland.
- American Boat and Yacht Council, ABYC A-16 (electric navigation lights) and ABYC E-11 (AC and DC electrical systems, voltage drop and conductor sizing).
- IEC 60529, Degrees of protection provided by enclosures (IP Code) (IP67 / IP68).
- ASTM B117, Standard Practice for Operating Salt Spray (Fog) Apparatus; IEC 60068-2-52, salt mist testing.
- NFPA 303, Fire Protection Standard for Marinas and Boatyards, and Electric Shock Drowning Prevention Association guidance on dock and marina electrical safety.
Image credits
- Bow port and starboard navigation lights: AI-generated illustration for LEDlights.org.
- COLREGs navigation light arcs diagram: LEDlights.org.
- Navigation light arc diagram: forthcoming / drawn by LEDlights.org.