The Complete Handbook of Watercraft Lighting

Chapter 1: Understanding Watercraft Lighting

Watercraft lighting is the controlled emission of visible light from a vessel, intended to serve one of three distinct purposes: navigation and signaling, operational utility, and habitability. A navigation light tells other vessels your position, your direction, and your status. A utility light lets the crew handle a line, inspect an engine bay, or read a chart without falling overboard. Habitability lighting makes the cabin functional after the sun goes down. Understanding this is the first step, because a common failure is buying a light that serves one purpose and trying to use it for another.

Consider the primary purpose: navigation. International regulations for preventing collisions at sea, often abbreviated as COLREGS, and their domestic equivalents in most nations (in the U.S., the Inland Navigation Rules) dictate precisely what lights a vessel must show at night. These are not aesthetic suggestions. A 20-foot center console boat and a 300-foot cargo ship are both required to present specific combinations of red (port), green (starboard), and white (all-round or masthead) lights to signal their angle and their type. A powerboat under 65.6 feet (20 meters) generally displays a red light on its port side, a green light on its starboard side, and a white all-round light at its stern. A sailing vessel under sail, on the other hand, shows only red and green sidelights and a white stern light, unless it is a small craft under 23 feet that may use a combined all-round light. If you