Part C — Lights and shapes

COLREGs Rule 22: Visibility of lights

Rule 22 sets the minimum range of navigation lights by vessel length. On a vessel under 12 m: masthead light 2 miles, sidelights 1 mile, stern, towing and all-round lights 2 miles.

What Rule 22 says

  1. Vessels 50 m or more: masthead light 6 miles; sidelight, stern light, towing light and all-round light 3 miles.
  2. Vessels 12 m to under 50 m: masthead light 5 miles (3 miles if under 20 m); sidelight, stern light, towing light and all-round light 2 miles.
  3. Vessels under 12 m: masthead light 2 miles; sidelight 1 mile; stern light, towing light and all-round light 2 miles.
  4. Inconspicuous, partly submerged vessels or objects being towed: white all-round light 3 miles.

This is a plain-English summary, not the official wording. For the exact text, see the IMO convention. In UK waters the rules are given legal force by the Merchant Shipping (Distress Signals and Prevention of Collisions) Regulations.

What it means on a yacht

A yacht's sidelights need only be visible at 1 mile (2 miles over 12 m). A ship at 15 knots covers that in four minutes, so do not count on being seen: assume you have not been.

Practise it

Test yourself on who gives way in the free COLREGs trainer, or print the rules of the road cheat sheets for the chart table.

Other rules in Part C