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.

6 Types of Navigation Lights

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

6. 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.

Navigation Light Requirements

Powerboats

For Powerboats Between 39.4 ft (12 m) and 164 ft (50 m):

While in motion, these boats must exhibit a green sidelight on the starboard side and a red sidelight on the port side. These sidelights must emit an unbroken light visible from straight ahead to 112.5 degrees on either side and must be seen from a distance of 2 nautical miles (NM). Powerboats less than 65.6 ft (20 m) in length can combine these sidelights into a single "bi-color" fixture positioned along the fore-aft centerline.

Additionally, a white stern light, facing aft, should be positioned as close to the stern as possible. Its light should form an unbroken arc spanning 135 degrees, with 67.5 degrees on each side of the vessel, and it should be visible from 2 NM away.

A forward-facing white "masthead" light, typically mounted on a pole or the front of the bridge, should be situated along the centerline of the boat. This masthead light must emit an uninterrupted beam covering 225 degrees (112.5 degrees on each side of the boat) with a visibility of 3 NM. It should remain unobscured by any equipment while the vessel is in motion. The specific height requirements for the masthead light are contingent on the boat's length and beam and can be found in the USCG Navigation Rules and Regulations Handbook.

For Powerboats Under 39.4 Feet (12 Meters):

While in operation, these vessels must exhibit the same side and stern lights as mentioned earlier, but with a reduced visibility requirement of 1 nautical mile (NM). Additionally, a masthead light with a 2-mile visibility range is necessary.

For power-driven vessels less than 39.4 feet, it's permissible to combine the functions of the masthead and stern lights into a single all-around white light (covering 225° plus 135°). If opting for this configuration, ensure that the all-around white light is positioned at least 3.3 feet (1 meter) above your sidelights

Small Powerboats

For powerboats under 23 feet (7 meters) that do not exceed a speed of 7 knots, you have the option to display a single all-around white light. However, it is advisable to use sidelights as well for enhanced visibility.

Sailboats

For Sailboats Under 65.6 Feet (20 Meters):

While sailing, you have several choices for displaying navigation lights:

• Option 1: Show a green light on the starboard side, a red light on the port side (or a combined bi-color light), and a white light at the stern. These lights have the same beam angle and visibility requirements as those for powerboats mentioned earlier.

• Option 2: Display a tri-color light at the masthead. This light incorporates a red light to port, a green light to starboard, and a white light aft, forming a complete circle of illumination. It's exclusively for use when sailing. When under power or motor-sailing with sails set, you must display standard navigation lights, including a steaming (masthead) light.

• Option 3: Show a green light on your starboard bow, a red light on your port bow, and a white light at your stern. You also have the option to display additional red and green all-round lights at the masthead, positioned 1 meter above the uppermost sail. The upper light should be red, and the lower light should be green. While this option is seldom used today, it remains acceptable. However, note that the red and green all-round lights at the masthead can only be used while under sail.

For Sailboats Under 23 Feet (7 Meters):

While sailing, it is advisable, whenever feasible, to utilize lights as described in options 1 or 2 above. These options offer superior visibility and aid in providing clear directional cues to other vessels. However, if implementing these options is not viable, the regulations stipulate that "the vessel shall exhibit an all-around white light or have ready at hand an electric torch or lighted lantern (flashlight) displaying a white light. This light must be displayed with sufficient lead time to prevent a collision." In such a situation, it is recommended to direct the light against your sail to create the most prominent signal possible and avoid potential collisions.

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.

Key Considerations for Boat Navigation Lights

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.