COLREG - Vessel Identification by Lights
Identify vessel type and activity from observed navigation lights and shapes per COLREG Rules 23 to 31.
Formula, assumptions, limits
COLREG Rules 23-31 establish navigation lights and shapes for various vessel types and activities. Lights are visible at night; shapes are equivalent day signals. The combination identifies vessel type, activity, and limitations on manoeuvrability.
Light combinations
PatternVessel/ActivityRule
Masthead+sidelights+sternPower-driven underwayRule 23 Sidelights+stern onlySailing or rowingRule 25 Two red over each otherNot Under CommandRule 27 Red-white-redRestricted Ability to ManoeuvreRule 27 Three red verticalConstrained by draughtRule 28 Green over whiteTrawlingRule 26 Red over whiteOther fishingRule 26 White over redPilot vesselRule 29 All-round whiteAnchorRule 30 Three vertical redAgroundRule 30
In short
Identify vessel type and activity from navigation lights.