Navigation Lights

All vessels underway at night are required to show navigation lights.

The only exceptions for showing navigation lights are small rowing and sailing boats, which instead are required to carry a torch or lantern showing a white light, exhibited in sufficient time to prevent a collision.

Navigation lights are vitally important because they not only indicate the presence of a vessel, but also its type (power-driven or sailing) and approximate direction of travel.

Types of Lights

For vessels under 12 metres in length, the following lights are used in various combinations depending on whether the vessel is sail or power-driven, and underway or at anchor.

White: Sternlight
White: All-round Light
White: Masthead Light
Red/Green: Sidelights

Light Angle of visibility Range of visibility

Masthead light 225° 2n. miles

Sidelights 112.5° 1n. mile

Sternlight 135° 2n. miles

All-round light 360° 2n. miles

Power-driven vessels while underway

Sailing vessels while underway

Vessels at anchor (either sail or power-driven)

A single white light visible all round.

Dredge signals

Vessels engaged in dredging, diving or underwater operations display the following signals to indicate on which side it is safe to pass.

Other vessels may pass on the side showing either:

For more information you can download our Navigation Lights Brochure (from our Safety/Publications page) or obtain a copy from any Department for Transport, Energy and Infrastructure Customer Service Centre.