Part C — Lights and shapes. What every vessel must show, by night and by day.

A vessel constrained by her draught may, in addition to the lights prescribed for power-driven vessels in Rule 23, exhibit where they can best be seen three all-round red lights in a vertical line, or a cylinder.

lightsshapesconstrained by draught

Reference only. Always navigate using the current official publication of the regulations and any local rules that apply.