Check Your Navigation Lights

Chris Riley by Chris Riley Updated on July 25, 2019. In nauticalknowhow

Check Your Navigation Lights

Will You Be Seen In Time?

Operating at night (or in reduced visibility) can present some special challenges. Not only is your depth perception lessened, bright lights on the shore can cast misleading reflections on the water and if you wear glasses, or worse yet bifocals, you simply don’t see as well at night as you do during the day.

It is not only important that you be able to identify other vessels operating in your proximity, it is equally important that other vessels see you.Most recreational vessels are less than 30 feet in length and, according to the Rules of the Road, shall be equipped with navigation lights. These lights not only have a certain arc through which they can be seen but must be seen from a minimum distance. The following lighting requirements are for recreational vessels less than 12 meters in length. (approximately 39.4′)

Light Arc Color Visible
boatlites.gif (3948 bytes)
Masthead Light



Starboard Sidelight


Green 1
Port Sidelight 112.5º Red 1
Sternlight 135º White 2

The arc of the lights and color allows you to determine the direction a vessel is moving. How good are your lights? You should test them to see how visible you might be at night. Whether on a trailer or at the marina, switch on your lights and see how well they can be seen. Walk away from the boat or row away, if you are at anchor or at a mooring, and see how visible the lights are as you move further away. How easy are they to see against the background of lights on shore?

Does your stern light shine dead astern over the required 135º arc or does it shine to one side or up or down. Can it be seen from the required 2 miles and why is that important? As an example, let’s say that your stern light for some reason can only be seen for 1/2 mile. You are underway at 8 knots and a large ship is approaching at 15 knots. The ship is only 4 minutes away from collision with you. By the time the ship “might” see you, identify the light and decide on the reaction that should be taken, it is too late. A ship traveling at 15 knots may take miles to stop.

Look at the stern light again, as you move from the stern toward the bow, does the stern light “disappear” as the sidelight “appears”? The stern light should disappear and sidelight appear at 22.5º abaft the beam. If you don’t see the green starboard sidelight or the red port sidelight when the stern light disappears there is a problem with the arc of one or all these lights. This means that if another boat were approaching you at the angle where no lights are seen there is increase risk of collision.

If both the sternlight and sidelights are seen brightly at the same time you still have a problem. A vessel approaching won’t know whether they are overtaking or crossing and whether they should give-way or stand-on.

You should also check to make sure that your masthead light disappears at the same time each sidelight disappears and they both disappear when the stern light appears.

Check your sidelights from dead ahead. You should see both red and green. However, by moving toward one side just 1-3º you should then see only one light. If you still see two lights, an approaching vessel won’t be able to tell which direction your are going.

It is very important to be seen from a distance but also for an approaching vessel to be able to determine your direction of travel.

When boating at night remember the following: “When two lights you see ahead, turn your helm and show your red”.




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