Part B · Section III

COLREGs Rule 19: Conduct of vessels in restricted visibility

Rule 19 says in fog or poor visibility, when vessels are not in sight of one another, there is no stand-on vessel: everyone goes at a safe speed and, if a vessel detected by radar is getting close, takes avoiding action in ample time, avoiding turns to port for vessels ahead and turns towards vessels abeam or astern.

What Rule 19 says

  1. Applies to vessels not in sight of one another when navigating in or near an area of restricted visibility.
  2. Proceed at a safe speed for the conditions. Power-driven vessels keep their engines ready for immediate manoeuvre.
  3. A vessel detected by radar alone: decide whether a close-quarters situation is developing or risk of collision exists. If so, take avoiding action in ample time.
  4. If that action is an alteration of course, avoid altering to port for a vessel forward of the beam (unless it is being overtaken), and avoid altering towards a vessel abeam or abaft the beam.
  5. Unless you have established there is no risk of collision, if you hear a fog signal apparently forward of your beam, or cannot avoid a close-quarters situation with a vessel forward of your beam, reduce to the minimum speed at which you can keep your course, take all way off if necessary, and navigate with extreme caution until the danger is over.

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

In fog a yacht has no right of way at all. Sound your fog signal, keep a radar watch if you can, listen hard, and be ready to stop. Get out of the shipping lanes and into shallow water where big ships cannot follow.

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 B

Frequently asked questions

Who has right of way in fog?

Nobody. Rule 19 applies to vessels not in sight of one another and has no stand-on or give-way vessel: every vessel must act to avoid a close-quarters situation.

Which way should you turn for a vessel on radar in fog?

For a vessel forward of the beam, avoid turning to port (so a turn to starboard is usual). For a vessel abeam or abaft the beam, avoid turning towards it.