COLREGs Rule 30
Anchor Light Rules: What a Yacht at Anchor Must Show
Published · Last checked October 2026
A vessel at anchor must show an all-round white light where it can best be seen, from sunset to sunrise and in restricted visibility (COLREGs Rule 30). Vessels of 50 metres or more show a second, lower white light near the stern. By day, an anchored vessel shows one black ball in the fore part. A boat under 7 metres need not show them unless it is in or near a channel, fairway, anchorage or where other vessels normally navigate.
What Rule 30 requires
| Length | Night | Day |
|---|---|---|
| Under 7 m, clear of channels and anchorages | Not required | Not required |
| Under 50 m | One all-round white light where best seen | One black ball forward |
| 50 m or more | All-round white forward, lower all-round white near the stern | One black ball forward |
| 100 m or more | As above, plus deck working lights must be used | One black ball forward |
A vessel under 50 m may show the two-light arrangement if it wishes, but one light is enough. For a yacht under 12 m the light must be visible for 2 miles.
Where to mount it
The rule says 'where it can best be seen'. Yachts usually use one of two positions:
- Masthead all-round white, often built into the tricolour unit. Visible from far off, but high above the eye line of a dinghy or small boat coming in at night.
- Low anchor light hung in the foretriangle or on the backstay, a few metres above deck. Many skippers find this more visible to nearby boats moving in an anchorage.
Some sailors show both. A low light illuminating the deck also helps others judge your size and distance.
The anchor ball
By day an anchored vessel shows a black ball in the fore part, at least 0.6 m in diameter for most vessels (smaller vessels may use a size in proportion). Many yachts skip it, but it is required unless you are under 7 m and clear of channels and anchorages. It tells other skippers you are not simply drifting or hove-to. Combined with an engine running ahead, a missing anchor ball can cause confusion when you are weighing anchor.
Sound signals at anchor in fog
In restricted visibility, Rule 35(g) requires a vessel at anchor to ring a bell rapidly for about five seconds at intervals of not more than one minute. A vessel under 12 m is not obliged to give these signals, but must make some other efficient sound signal at intervals of not more than two minutes.
Revise anchoring in the anchoring lesson and the how to anchor a yacht guide.