COLREGS Lights & Shapes by Vessel Type

A power-driven vessel underway shows a white masthead light forward, red and green sidelights, and a white sternlight. Vessels 50 meters or more in length must also show a second masthead light abaft and higher than the forward one. Small vessels under 7 meters have a simplified option.

A sailing vessel underway under sail alone shows sidelights and a sternlight. Vessels under 20 meters have additional options including a combined tricolor lantern at the masthead and optional red-over-green all-around lights. A sailing vessel using its engine is a power-driven vessel and must show a black cone by day.

A vessel towing astern shows two forward masthead lights in a vertical line (three if the tow exceeds 200 meters), sidelights, a white sternlight, and a yellow towing light positioned directly above the sternlight. Pushing ahead or towing alongside uses two masthead lights but no yellow towing light. Tows over 200 meters require a diamond dayshape on both vessels.

A vessel engaged in fishing (gear that restricts maneuverability — not trolling) shows two all-around lights: red over white for all fishing except trawling, and green over white for trawlers. Sidelights and sternlight are added only when the vessel is making way. The biconical (apex-to-apex) dayshape applies to both.

A vessel not under command (NUC) — unable to maneuver due to an exceptional circumstance such as a breakdown — shows two all-around red lights in a vertical line. When making way it adds sidelights and a sternlight. It does NOT show masthead lights. By day it shows two black balls in a vertical line.

A vessel restricted in ability to maneuver (RAM) shows three all-around lights in a vertical line — red, white, red. When making way it adds masthead lights, sidelights, and a sternlight. The dayshape is a ball over a diamond over a ball. Dredges and vessels with underwater obstructions show additional colored signals indicating which side is clear.

A vessel constrained by her draft (CBD) may show three all-around red lights in a vertical line and a cylinder dayshape, in addition to the normal lights of a power-driven vessel. These are optional, not mandatory. CBD status applies only to power-driven vessels under COLREGS — there is no equivalent category in the US Inland Rules.

A vessel engaged on pilotage duty shows two all-around lights at or near the masthead — white over red. When underway it adds sidelights and a sternlight. When at anchor it shows the white-over-red plus the appropriate anchor lights under Rule 30. A pilot vessel not on duty shows the lights of an ordinary vessel of its size.

A vessel at anchor shows all-around white anchor light(s). Vessels under 50 meters show one all-around white light positioned where it can best be seen. Vessels 50 meters or more show two — a higher one forward and a lower one aft. Vessels over 100 meters should illuminate their decks. No sidelights, sternlight, or masthead lights are shown at anchor.

A vessel aground shows all the anchor lights appropriate for its length, plus two additional all-around red lights in a vertical line. By day it shows anchor ball(s) plus three black balls in a vertical line. The two red lights are what distinguish a vessel aground from one merely anchored.