The lights a yacht shows tell other vessels what she is and what she's doing. The COLREGs set them internationally; in US waters the Inland Rules in 33 CFR part 83 follow the same numbering. Rules 20 to 31 are Part C, lights and shapes. Surveyors check the boat can show what the rules require for the way she's used.
What it covers
Arcs and colours, Rule 21. A masthead light is white over 225 degrees, from right ahead to 22.5 degrees abaft the beam each side. Sidelights are green to starboard and red to port, each over 112.5 degrees. The sternlight is white over 135 degrees. An all-round light shows 360 degrees.
Ranges, Rule 22.
| Light | Under 12 m | 12 m to under 20 m |
|---|---|---|
| Masthead | 2 miles | 3 miles |
| Sidelight | 1 mile | 2 miles |
| Sternlight | 2 miles | 2 miles |
| All-round | 2 miles | 2 miles |
Power-driven vessels, Rule 23. A masthead light forward, sidelights and a sternlight. Under 12 metres, an all-round white light and sidelights instead.
Sailing vessels, Rule 25. Sidelights and a sternlight. Under 20 metres they may be combined in one lantern at the masthead. Under sail and engine together, a cone apex down by day, optional under 12 metres.
At anchor and aground, Rule 30. An all-round white light, or one ball by day, in the fore part. Under 50 metres, one all-round white light is enough. Aground, two all-round red lights and three balls in a vertical line, not required under 12 metres.
What surveyors check against it
The right set for the use. A tricolour is for sailing only. A sailing yacht that motors at night needs a steaming light, sidelights and a sternlight it can switch on separately.
Each light working, at the right arc. Switch each on and look at it from ahead, abeam and astern. Sidelight screens and placement decide the arc.
Certified fittings. For boats covered by 33 CFR 183, section 183.810 requires lights certified by a Coast Guard listed laboratory to ABYC A-16, labelled with "USCG Approval 33 CFR 183.810", the standard, the laboratory and the visibility in miles. Small lights carry "USCG" and the range, such as "USCG 2nm".
Shapes aboard. An anchor ball, and a motorsailing cone on yachts of 12 metres and over.
See navigation lights.
Citing it in a finding
Name the rule: "Vessel uses a masthead tricolour as her only navigation light and is motored at night. Fit a separately switched steaming light, sidelights and sternlight as required for a power-driven vessel, COLREGs Rule 23." Give the vessel's length, because the ranges and exemptions change at 7, 12 and 20 metres.