Rule 19 applies to vessels not in sight of one another when navigating in or near an area of restricted visibility.
Core requirements
- Every vessel shall proceed at a safe speed adapted to the prevailing circumstances and conditions of restricted visibility. A power-driven vessel shall have her engines ready for immediate manoeuvre.
- Every vessel shall have due regard to the prevailing circumstances when complying with Rules 4 to 10.
- A vessel that 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.
Avoiding action by radar detection
- Avoid an alteration of course to port for a vessel forward of the beam, other than one being overtaken.
- Avoid an alteration of course towards a vessel abeam or abaft the beam.
Vessels that hear a fog signal
A vessel which hears, apparently forward of her beam, the fog signal of another vessel, or which cannot avoid a close-quarters situation with a vessel forward of the beam, shall reduce her speed to the minimum at which she can be kept on her course. She shall if necessary take all her way off and, in any event, navigate with extreme caution until danger of collision is over.
Practical habits
- Call the Master early, when visibility starts to fall.
- Have engines ready, reduce speed, post an extra look-out.
- Switch on navigation lights and check sound signals (see Part 7).
- Plot radar targets systematically; do not rely on one or two observations.
- Be extra careful in narrow channels, at anchor and near traffic separation schemes.
Remember: the fact that a target is not coming straight at you does not mean you are safe.