Module 5 - COLREGs
Navigation Lights
An ordinary power-driven vessel underway shows a forward masthead light, sidelights and a sternlight. A vessel 50 metres or more also shows a second masthead light abaft and higher than the forward one. A power-driven vessel under 50 metres is not obliged to show that second masthead light, although Rule 23 permits it to do so.
A sailing vessel underway under sail shows sidelights and a sternlight. A vessel under 20 metres may combine those three sectors in one lantern at or near the masthead. It may instead add the optional all-round red-over-green pair, but that pair must not be shown with the combined lantern. A yacht using propelling machinery is treated as power-driven even if sails remain set.
Status patterns are read with any prescribed underway lights. Not under command is red over red; restricted in ability to manoeuvre is red-white-red; fishing other than trawling is red over white; and trawling is green over white. NUC, RAM and fishing vessels making way through the water also show sidelights and a sternlight, so the complete picture can reveal both status and aspect.
A vessel under 50 metres at anchor may show one all-round white light where it can best be seen. An aground vessel shows the anchor light or lights plus two all-round red lights vertically. Visibility, background lighting, sector cut-off and aspect can hide part of a pattern, so keep observing rather than treating one glimpse as a complete identification.
- Power-driven underway: prescribed masthead light or lights, sidelights and sternlight
- Sailing under sail: sidelights and sternlight, with size-specific alternatives
- Status lights must be combined with aspect, movement and any other visible lights
- Lights help identify a vessel; bearings, range and the applicable steering rule decide the action
| Observed pattern | Initial interpretation | What to check next |
|---|---|---|
| Red over red | Not under command | Making way lights, aspect, range and relative movement |
| Red-white-red | Restricted in ability to manoeuvre | Nature of work, obstruction side and safe passing room |
| Red over white | Fishing other than trawling | Making way lights, gear indication and risk of collision |
| Green over white | Trawling | Making way lights, gear indication and risk of collision |
| Anchor light(s) plus red over red | Aground | Position, charted hazards and a safe passing distance |
Optional quick check
Section 9 of 9
What does red over red plus a visible sidelight and sternlight indicate?
Continue studying COLREGs
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