It happens to all of us who have been boating long enough, we unexpectedly get back late from a cruise. If the sun sets and we don’t have the benefit of see in the dark technology, we have to rely on interpretation of boat buoy and channel lights. Here’s a quick guide.

Take a look at the illustration to this piece. If you see these vessels in front of you lit in this configuration and know you have a fast enough boat to split the difference between them instead of waiting to take the stern of both – don’t.

That’s exactly what happened in Puget Sound a few years ago. A cruiser tried to pass between the two sets of moving lights at night without realizing that the specific light patterns indicated that the second vessel was being towed.

The cruiser was torn apart by the tow chain and several people were killed.

One key to night boating safety is knowing what navigation lights mean. On display is the pattern for a night tow: The towing vessel must display two masthead lights in a vertical line. When the length of the tow from the stern of the towing vessel to the aft end of the tow exceeds 200 meters, the towing vessels must display three lights vertically. It must also display sidelights, a stern light, a towing light directly above the stern light; and when the length of the tow exceeds 200 meters, a diamond shape where it can best be seen.

A vessel being towed must display sidelights, a stern light and when the length of the tow exceeds 200 meters, a diamond shape where it can best be seen.

The night pattern on display means that that by daylight, the scenario in the next image is what we would be seeing. By daylight, you can’t see the tow chain so don’t assume it isn’t there. It droops during a tow. The heavier it is, the more it sags.

Remember skipper Rick BeauChemin’s dictum, “The most important thing about sailing at night is to observe and be observed.”

The light patterns we’ll discuss here are not only for you to recognize what’s out there, but for you to display yourself. It’s important to check your boat’s navigation lights before you go out of a sail. I always carried spare bulbs. The Coast Guard will only care if your lights work, not if they did work once.

We’ll only cover the basics. For more detailed information, turn to the free brochure "Federal Requirements for Recreational Boats", from the Coast Guard Customer Information Line at 800-368-5647.

Coming back into Marina del Rey, the North and South entrances are lit with green and red lights. Keep this phrase in mind, “Red right returning.” Put the red light on your right when you are returning to the harbor.

On a boat itself over 7 meters in length, the green  navigation or running light is displayed on the right (or starboard) bow while the port shows a red light. Each must cover a forward arc of 112.5°. The white stern light must cover 135° completing the 360° of the horizon. The coverage is very specific so boaters can judge each others’ relative positions to apply the rules of the road that I’ve outlined for power boaters and sailboats. Remember, if sailboat is under power, even if with sails up, it is governed by the rules for power boaters. These lights are required on boats between sunset and sunrise.

Keep it these night light patterns in mind. Specifics follow based on boat length.

For boats under 12 meters, here is what is needed:

Rowboats, kayaks, canoes  or sailboats less than 7 meters have the option of displaying sailboat lights but at the very least should have a flashlight showing a white light that can be snapped on and used soon enough to prevent a collision.

Sailboats between 7 and 12 meters may display separate or combination red and green sidelights visible for one nautical mile. The white stern light must be visible 2 nautical miles. Another option is to display a tri-colored masthead light.

Powerboats may show separate or combination red and green sidelights visible for one nautical mile placed over the hull at least a meter below the mast head light. The masthead light has to be white with 225° of coverage, visible for 2 nautical miles. The white stern light should be visible for 2 nautical miles. Another option is to have one white light visible for 360° along with red and green side lights.

For boats from 12-20 meters adhere to these rules:

For sailboats, the red and green sidelights and white stern light must all be visible for two nautical miles. Again a tri-colored mast head light is another option

Sidelights for powerboats in this range must each be visible for 2 nautical miles, located above hull at least 1 meter below the masthead light. The masthead light must be white covering an arc of 225°, visible for three nautical miles. The white stern light must be visibled from a distance of 2 nautical miles. 

Masthead lights are optional for boats under 50 meters. Those over 50 meters must display two.

Anchored Boats:

Boats less than 7 meters aren’t required to display an anchor light unless they are in a narrow navigable channel. Otherwise all bigger boats up to 50 meter must display a 360° white light, visible for 2 miles set where it can best be seen. Boats at anchor should also display a ball shape. To avoid confusion, when under anchor be sure to turn off the sidelights and stern light.

Always err on the side of caution at night. Emergencies are exacerbated by darkness. 

Editor's Note: Corrected on Friday, Sept. 16, 2011, that boats over 7 meters in length have the green  navigation or running light displayed on the right (or starboard) bow while the port shows a red light.