Boating at Night: Lights, Speed, Night Vision and Reading Other Boats

The navigation rules require your lights from sunset to sunrise (and in restricted visibility). Turn them on and walk around the boat. Red should show on the left (port) bow, green on the right (starboard) bow, and white at the stern or on an all-round pole. A power boat under 12 meters (39.4 feet) may show an all-round white light plus sidelights instead of a separate masthead light and sternlight. BoatUS notes lights should be visible 1 to 2 miles away, but loose connections and crazed, cloudy lenses cut that a lot. Clean the lenses and fix weak lights before you go. See our navigation-lights guide for repairs.

Carry spare bulbs or a spare LED fixture and fuses, several flashlights (one with a red setting), spare batteries, and a charged spotlight. Discover Boating stresses having backups you can grab right away: if the main spotlight dies, you need another light immediately. Keep your sound device (horn or whistle) within reach of the helm, and make sure your flares or electronic distress light are in date.

Under Rule 20, you may not show other lights that can be confused with navigation lights or that get in the way of keeping a proper lookout. Discover Boating says to turn off headlights, spotlights and other lights that could interfere while you are underway. That includes bright deck lights, cockpit floodlights and colorful accent or underwater lighting. They wreck your night vision and can hide or confuse your navigation lights for other boaters.

Give your eyes time to adjust to the dark before you leave. BoatUS notes that a few seconds of white light can cost you several minutes of night vision. Use a red (or blue-green) headlamp for reading charts and finding gear. Put your chartplotter, sounder and phone in night mode and turn the brightness way down. Glance at screens briefly, then look back outside.

Logs, crab-pot floats, unlit moorings and rocks are nearly invisible at night. Discover Boating notes many experienced night boaters run at about half their daytime cruising speed. The navigation rules require a safe speed that lets you stop in time. They list background shore lights as one of the factors that make other boats and hazards harder to see. Going slower also makes the boat quieter, so you can hear surf, engines and other boats.

The driver should not be the only set of eyes. Put a sober, reliable person on lookout, ideally with binoculars, which gather light and help you pick out boats, buoys and landmarks. Turn off the music and keep talking quiet so you can hear. Have the lookout scan all the way around, including astern, where faster boats come up from behind.

Lights tell you which way another boat is pointing:

• Red and green together (with white above): the boat is coming straight at you. Rule 14 says when two power boats meet head-on, each turns to starboard (right) and they pass port-to-port. If you are not sure whether it is head-on, assume it is.

• Red only (plus white): you are seeing its port side. If it is on your right (starboard), Rule 15 makes you the boat that keeps out of the way. Slow down or turn so you pass behind it, not ahead.

• Green only (plus white): you are seeing its starboard side. Hold your course and speed, but be ready to act if the other boat does not.

• White only: you are probably behind a boat moving away from you, or looking at an anchored boat, or a small boat with only an all-round white. Treat it with care until you know which.

• Flashing blue light: on U.S. inland waters, only law enforcement boats may show it (33 CFR 88.05). Slow down and be ready to stop.

• Alternating red and yellow flashing light: a public safety or similar boat at work, such as assisting a disabled boat, firefighting or search and rescue (33 CFR 88.07). It gives that boat no right of way, but give it room.

Sailboats under sail show red and green but no white masthead light. Larger and commercial vessels show more lights. Learn them from the Navigation Rules or a boating course, and give tugs and ships plenty of room.

Do not assume everyone has lights on. BoatUS warns that a boat without lights may not be seen until it is too late, and Discover Boating says to stay alert for unlit vessels. Paddlers, anglers in small skiffs and boats with dead batteries are common culprits. This is another reason to keep your speed down.

Use the spotlight in quick sweeps to find a marker, a dock or debris, then turn it off. Long beams kill your night vision and reflect off spray and haze. Never shine it at the helm of another boat; you will blind that driver. If a fast boat or ship does not seem to see you, shine the light on your own boat or sails to show that you are there.

Stick to well-marked channels where you can. Discover Boating notes reflective tape on markers makes them much easier to find than cutting across open water. Lighted buoys and markers flash in a set pattern shown on the chart and the plotter, so you can match the flash to the right marker. Shore lights in the background make markers and boats hard to pick out, so double-check against the chart.

Electronics help a lot at night, but charts can be out of date and buoys get moved. Use the plotter, depth sounder and, if you have them, radar and AIS together with your eyes and ears. Landmarks look different in the dark, and a far-off street lamp can look like an anchor light.

Everyone wears a life jacket, and the driver clips on the engine cut-off lanyard or wireless fob. Brief the crew on what to do if someone goes over, and keep a throwable device and a light ready to toss. Do not let people sit on the bow or gunwales at night.

Night boating needs all your concentration. The USCG notes that alcohol cuts night vision, depth perception and peripheral vision and makes it harder to tell red from green, exactly the skills you need after dark. The USCG also says alcohol is involved in about a third of recreational boating deaths, and boating under the influence is illegal in every state. The driver and the lookout should stay sober.

Before you head out, or as soon as you know you will be out late, tell someone ashore your route and expected return so they do not call a search for nothing, or do call one if you really are overdue. Carry an anchor and anchor light so you can stop and wait out problems instead of pushing on.

Anchoring after dark, even just to fish or watch fireworks? Rule 30 (33 CFR 83.30) calls for an all-round white light where it can best be seen. Your red and green sidelights go off, because they tell others you are moving. A boat under 7 meters (about 23 feet) is excused only when it is not in or near a channel, fairway, anchorage or anywhere other boats normally travel, and boats under 20 meters in a Coast Guard special anchorage area are excused too. In practice, if anyone could come your way, show the light.