All boats operating between sunset and sunrise, or in other conditions that limit visibility like fog, are required to display navigation lights. There are several different navigation lighting requirements for different types and sizes of boats, as well as what they are being used for, and it is on you as the owner or operator of the boat to know what is required and implement it properly. So before you buy navigation lights for your boat, make sure you know the basics of what each type of light is for, when to use it, and how it applies to your boat.

Types of Navigation Lights

Sidelights: Sidelights are fairly self-descriptive, as they are navigation lights that indicate which side of the boat someone is seeing when they look at your lights in the dark. A red sidelight is for the port side of the boat, while a green sidelight is for the starboard side. Depending on the size and purpose of the boat, these are typically mounted right on the bow or near the bow of the boat, as they must be visible from dead ahead and 112.5° aft on either side.

Bi-Color Light: A bi-color light is one fixture that combines the red and green sidelights, and is typically used on smaller boats and gets mounted as far forward on the bow as possible.

Tri-Color Light: A tri-color light is one fixture that combines the red and green side lights with a stern light as well. This is typically seen on sailboats, mounted at the top of the mast and used when the boat is under sail.

Stern Light: As the name indicates, a stern light is a white light intended for your boat to be visible from behind, so it faces backwards with 135° of visibility, 67.5° on each side.

All-Around Light: An all-around light is white and has 360° of visibility. It is typically the light at the highest point on the boat compared to all other navigation lights. All-around lights are also used as anchor lights, to indicate that the boat is resting at anchor.

Masthead Light: Masthead lights are the complement to stern lights, shining a white light directly ahead with 225° of visibility, totaling 360° when combined with a stern light. As the name indicates, masthead lights installed at or near the highest point on the boat.

Visibility Range Requirements

One common mistake that boat owners make when purchasing navigation lights for their boat is choosing lights that do not meet the visibility range requirements for their size of boat. Different boats have different requirements, with the general rule being that larger boats must be visible from further away than smaller boats. Below are the international requirements for visibility range.

Boats less than 12 meters (39’5”) must have sidelights with a minimum visibility range of 1 nautical mile (nm) and all other lights must be visible from 2nm.

Boats between 12m & 20m (65’8”) must have a masthead light that is visible from 3nm and all other lights must be visible from 2nm.

Boats between 20m & 50m (164’) must have a masthead light visible from 5nm and all others must be visible from 2nm.

For any boats over 50m, the masthead light must have a 6nm visibility range and all others must be visible from 3nm.

When and How to Use Your Navigation Lights

For the majority of recreational boats, there are three different scenarios in which you must display navigation lights: under power, under sail and at anchor. For commercial purposes like towing a barge, drag-net fishing and so on, there are specific lighting configurations required for each of a vast array of different activities, so it’s always best to consult an expert in that specific industry if you’re operating your boat commercially.

When under power, for recreational purposes, your boat must display both side lights as well as a form of 360° white light, either through an all-around light (boats under 12m in length) or with a combination of a masthead light and stern light (boats over 12m). When under sail, a sailboat needs to display both side lights and a stern light, which can be done with separate lights down on the hull or with a single tri-color light at the top of the mast. If your boat is at anchor in an area that is not specifically designated as an anchorage, you must display a single all-around white light that is visible from 360°. For oar or paddle boats like canoes and kayaks, they are treated as sailboats under sail, though if installed lights aren't possible a handheld flashlight is acceptable.

Final Thoughts

When it comes to navigation lights the most important factors are configuration and visibility. Adhering to the proper configuration of your navigation lights is essential so as not to confuse any other boaters on the water about your direction of travel and type of vessel when observing your navigation lights. As long as they’re configured properly, being more visible at night is always better, so many boaters opt for more powerful lights that have longer visibility ranges than the required minimum for their particular boat.

If you plan to operate your boat at night frequently, it’s always a good idea to carry spares onboard in case there’s a failure in any of your navigation lights. Depending on your lights, you may be able to carry just bulbs, or you may have to replace an entire fixture in the event of a failure, depending on the model of light. Manufacturers like DHR make navigation lights that are field-serviceable and offer kits of spare parts to make onboard repairs easy.

If you have any questions or doubts about your navigation lighting, it’s always best to consult with an expert or with your local authorities like harbormasters and Coast Guard.