Navigation Lights For Vessels and Powerboats


Navigation lights are used to prevent collisions at night or in times of reduced visibility, and are an essential tool in keeping you and your vessel safe. Nav lights allow you to see other nearby vessels, and allow other vessels to see you.

Nav lights also provide information about the size, activity, and direction of travel.

Vessels are required to show the proper navigation lights from sunset to sunrise in all weather conditions, good and bad. During these times, no other lights that could be mistaken for lights specified in the Rules of the Road can be displayed, nor any lights that impair the visibility or distinctive character of navigation lights, or interfere with the keeping of a proper lookout. The Rules also state that navigation lights must be shown in conditions of reduced visibility, and may be shown at other times considered necessary.

On any vessel, navigation lights have a specific color, (white, red, green, yellow, blue), arc of illumination, range of visibility, and location, as required by IALA

Power driven vessels underway shall exhibit a masthead light forward, sidelights and a stern light. Vessels less than 12 meters in length may exhibit an all around white light and side lights. Power driven boats on the Great Lakes may carry an all around white light in stead of a second masthead light and stern light combination.

By understanding the characteristics of Nav lights, you can determine an appropriate course of action as you approach another vessel.

Navigation Lights for Vessels and Powerboats (1)
Navigation Lights for Vessels and Powerboats (3)
Navigation Lights for Vessels and Powerboats (2)


Colored lights - red on port and green on starboard - showing an unbroken arc of the horizon of 112.5 degrees, from dead ahead to 22.5 degrees abaft the beam on each side.

Combination lights

Sidelights may be combined in a single fixture carried at the centerline of the vessel.

Stern light

A white light showing over an unbroken arc of the horizon of 135 degrees, centered on dead astern.