Rule 19 - Conduct of Vessels in Restricted Visibility

Official COLREGS Extract (c)

“Every vessel shall have due regard to the prevailing circumstances and conditions of restricted visibility when complying with the Rules of Section I of this Part.”

In Plain English 

• Always think about weather, sea state, and visibility before you act.

• Restricted visibility changes how you apply the normal collision rules.

• Be extra cautious — the normal “give-way” rules don’t always apply in fog.

• Don’t forget to call the Master early if visibility is poor.

Official COLREGS Extract (d)

“A vessel which detects by radar alone the presence of another vessel shall determine if a close-quarters situation is developing and/or risk of collision exists. If so, she shall take avoiding action in ample time, provided that when such action consists of an alteration of course, so far as possible the following shall be avoided:

(i) an alteration of course to port for a vessel forward of the beam, other than for a vessel being overtaken;
(ii) an alteration of course towards a vessel abeam or abaft the beam.”

Plain English for Cadets

• If radar shows another ship

  • Work out if there’s a risk of collision.

  • Act early, don’t wait until it’s too late.

• When altering course:
  • ❌ Don’t turn to port for a ship ahead (unless overtaking).
  • ❌ Don’t turn towards a ship beside or behind you.
  • ✅ Safe action = normally a starboard turn or slowing down.

• Always use ARPA plotting if fitted.

Official COLREGS Extract (e)

“Except where it has been determined that a risk of collision does not exist, every vessel which hears apparently forward of her beam the fog signal of another vessel, or which cannot avoid a close-quarters situation with another vessel forward of her beam, shall reduce her speed to the minimum at which she can be kept on course. She shall, if necessary, take all her way off and in any event navigate with extreme caution until danger of collision is over.”

Plain English for Cadets

• If you hear a fog signal ahead

  • Slow down to the minimum steerage speed.

  • Don't assume the Vessel is ahead, especially if you don't have an ARPA Target ahead.

  • Be ready to stop completely.

  • Navigate with extreme caution until the danger has passed.

• Post an extra lookout and use all available means (radar, AIS, sound signals, bridge team support).

Key Bridge Advice for Cadets

• Call the Master early.

• Double the lookout.

• Safe Speed First. – Slow is safe in fog.

• Radar Early, Bold Action. – Don’t delay manoeuvres.

• Don’t Turn Into Danger. – No port turns ahead, no turns towards abeam/astern.

• Slow, Stop, Caution. – Hearing a foghorn ahead = engines ready to stop.