COLREGs Rule 28: Vessels constrained by their draught

Rule 28 says a vessel constrained by its draught may show, in addition to its power-driven lights, three all-round red lights in a vertical line, or by day a cylinder.

What Rule 28 says

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

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

Three reds or a black cylinder mean a deep-draught ship that cannot leave the channel. Rule 18(d) says you must avoid impeding it, so move out of its way early.

Lights and shapes under Rule 28

Constrained by draught Rule 28
Three all-round red lights in a vertical line, in addition to normal power-driven lights. Keep out of her way in the channel.

Drawn from the starboard side at night, with the day shapes below. See every aspect in the lights and shapes trainer.

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

Frequently asked questions

What do three red lights mean on a ship?

A vessel constrained by its draught under Rule 28. By day it shows a black cylinder. Other vessels must avoid impeding it.