To See and Be Seen: The Fundamentals of Boat Lighting

Boating at night can be a fantastic experience – the waterways are less crowded, the fishing is usually pretty good, not to mention the whole moon, stars and skies aspect of a nocturnal cruise.

However, because we mortals aren’t endowed with particularly sharp night vision faculties, it’s important that our boats have the proper lights to allow other mariners to see us – and vice-versa. These lights are called navigation lights (nav lights in the nautical vernacular); they’re an uncomplicated, yet critical component of boating after hours.

Navigation Lights by the Book
To ensure we’re delivering the most accurate information, we’ve consulted Navigation Rules, International-Inland (COMDTINST M16672.2D), a comprehensive volume offered by the United States Coast Guard® (USCG) that provides in-depth guidelines on almost every navigational scenario imaginable, including detailed nav light requirements for vessel of all lengths.

For the sake of simplicity, we’re going to address the navigation lights and their locations for power boats under 12 meters (39.37 feet) long, according to Rule 21, Inland Lights and Shapes.

White Lights
Your boat must have a masthead light, located as close as possible to the fore-aft centerline of the hull and a stern light. This two-light configuration is frequently found on larger craft, such as big cruisers; however, a common (and legal) solution is an elevated single all-around white light mounted at the starboard stern (right rear corner) of the boat.

Red and Green Lights
To enable other boaters to determine what side of your vessel they’re looking at, a red light is required to be displayed on the port (left) side and a green light on the starboard (right) side of your boat.

In lieu of individual red and green sidelights, a single bow-mounted 1/2 red-1/2 green combination navigation light is acceptable.

Exceptions
Slow, motor-driven boats less than 7 meters (about 23 feet) long that don’t go faster than 7 knots (8 mph) are compliant if a single all-around white light is displayed, and red/green lights, if practical.

A rowboat isn’t required to have nav lights; however if you’re out at night in a rowboat without lights, you must have either a white flashlight or lantern to alert another vessel to prevent a collision in which you would surely come up short.

Using Nav Lights
Navigation lights must be used from sundown to sunrise, or when operating in situations of reduced visibility (fog/haze).

While underway, the white light(s) and the red/green lights have to be turned on; if you stop and anchor at night, only display the white light(s) – the red/green lights go off at anchor.

Interpreting What You See
Let’s say you’re on the lake post-sundown and in the distance, you see a white light and red light – what is it? Because the white light is likely at the stern, and the red light is definitely on the port side, you’re looking at the port side of a boat that’s probably crossing from right-to-left in front of you.

Conversely, a white light and a green light would designate the starboard side of a boat potentially travelling from left-to-right across your bow.

If you see a red/green light, and no white light, there is a strong possibility that another boat is heading directly towards you – take action to avoid a collision immediately.

A single white light should indicate a boat at anchor – or a boat without functioning red/green lights – steer clear either way.

Proceed with Caution
Driving your boat at night is an acquired skill that takes a bit of practice to reach a reasonable level of comfort. The lake looks completely different once the sun goes down; familiar landmarks are cloaked in darkness and replaced by lights from houses, cars, radio towers – or the shore may disappear altogether, depending on where you’re boating.

Slow down. Dim the instrument panel lights (if possible). Turn off interior lights and courtesy lights. Don’t use a spotlight unless absolutely necessary; a hand-held spotlight reflecting off a white foredeck can ruin your night vision for quite a while (like looking at the flash when someone takes your picture).

We recommend wearing eye protection during nighttime ops – clear safety glasses aren’t expensive and work well – remember, the bugs like to zip around after dark, too.

Overall
If you go boating at night, check all rules and regulations first, take your time, use your head, and you’ll soon find an entirely new world opening up for your pleasure. Y

Resources
U.S. Coast Guard’s Boating Safety Division (CG-5422)
uscgboating.org

U.S. Coast Guard Navigation Center
navcen.uscg.gov

Quick Reference:  Navigation Lights

Under power
Sidelights, stern light, masthead light
Boats 16' or longer must also have an 360° all-around white anchor light capable of being lit independently from the red/green/white running lights

Sailboats under power are considered powerboats and must follow "under power" rules.

Power boats/rowboats under 7m and under 7 knots can substitute a white flashlight/lantern in place of the required lights.

At Anchor
All around white light visible for 2nm at night unless in a chart-designated anchorage

Although these aren’t quick reads, we’re obligated to give you applicable excerpts from The Rules – chapter and verse – straight from the USCG (Revised Oct. 19, 2009). See Resources for more information and complete details.

INLAND
Lights and Shapes

RULE 21 – Definitions
(a) “Masthead light” means a white light placed over the fore and aft centerline of the vessel showing an unbroken light over an arc of the horizon of 225 degrees and so fixed as to show the light from right ahead to 22.5 degrees abaft the beam on either side of the vessel, except that on a vessel of less than 12 meters in length the masthead light shall be placed as nearly as practicable to the fore and aft centerline of the vessel.

(b) “Sidelights” mean a green light on the starboard side and a red light on the port side each showing an unbroken light over an arc of the horizon of 112.5 degrees and so fixed as to show the light from right ahead to 22.5 degrees abaft the beam on its respective side. On a vessel of less than 20 meters in length the sidelights may be combined in one lantern carried on the fore and aft centerline of the vessel, except that on a vessel of less than 12 meters in length the sidelights when combined in one lantern shall be placed as nearly as practicable to the fore and aft centerline of the vessel.

(c) “Sternlight” means a white light placed as nearly as practicable at the stern showing an unbroken light over an arc of the horizon of 135 degrees and so fixed as to show the light 67.5 degrees from right aft on each side of the vessel.

(e) “All-round light” means a light showing an unbroken light over an arc of the horizon of 360 degrees.

RULE 22 – Visibility of Lights
The lights prescribed in these Rules shall have an intensity as specified in Annex I to these Rules, so as to be visible at the following minimum ranges:
(c) In a vessel of less than 12 meters in length:
—a masthead light, 2 miles
—a sidelight, 1 mile
—a sternlight, 2 miles
—a white … all-round light, 2 miles