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19

Conduct of Vessels in Restricted Visibility

Radar-only contact ahead of the beam in restricted visibility; the vessels are not in sight. If avoiding action requires a course alteration, avoid turning to port so far as possible, except for a vessel being overtaken. The amber arc is a conditional caution, not a recommended manoeuvre.

Rule 19 applies to vessels not in sight of one another when navigating in or near an area of restricted visibility.

a
Every vessel shall proceed at a safe speed adapted to the conditions. A power-driven vessel shall have her engines ready for immediate manoeuvre.
b
Every vessel shall have due regard to the prevailing circumstances and conditions of restricted visibility when applying Rules 4 to 10.
c
A vessel detecting another by radar alone shall determine whether a close-quarters situation or risk of collision is developing. If so, she shall take avoiding action in ample time.
d
If the avoiding action consists of an alteration of course, so far as possible avoid:
  • 1altering to port for a vessel forward of the beam, other than for a vessel being overtaken
  • 2altering towards a vessel abeam or abaft the beam
e
Unless risk of collision has been determined not to exist, a vessel that hears a fog signal apparently forward of the beam, or cannot avoid a close-quarters situation with a vessel forward of the beam, shall reduce speed to the minimum at which she can be kept on course and, if necessary, take all way off. She shall then navigate with extreme caution until danger of collision is over.
Three relative positions of one radar contact on the starboard quarter, the nearest solid echo being current. The vessels are not in sight in restricted visibility. When altering course to avoid danger, avoid turning towards a vessel abeam or abaft the beam so far as possible; no opposite turn is automatically safe.

IMO COLREG 1972Official text

Full wording of the rule, reproduced from the official source below.

(a) This Rule applies to vessels not in sight of one another when navigating in or near an area of restricted visibility. (b) 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 maneuver. (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. (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. (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.
Source:

STCW Bridge Watch Lens

(b) 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 maneuver.

Rule 19 applies to vessels not in sight in or near restricted visibility.

In radar-only avoiding action, avoid altering to port for a vessel forward of the beam so far as possible, except a vessel being overtaken.

After manoeuvring, keep monitoring bearing, range, CPA/TCPA and passing distance until the other vessel is finally past and clear.

Exam Focus

Start every scenario by classifying the encounter: overtaking, head-on, crossing, narrow channel, traffic separation, or restricted visibility.

For vessels in sight, every overtaking vessel keeps clear until finally past and clear.

Rule 13 takes precedence over Part B Sections I and II; it does not override the other Parts of COLREG.

Rule 19 does not create stand-on and give-way vessels.

If the vessels are not in sight of one another, do not apply the crossing or head-on rules.

Key Takeaways

1

Rule 19 applies when vessels are not in sight in or near restricted visibility

2

There is no stand-on vessel under Rule 19; every vessel must assess the situation and act as required

3

So far as possible avoid a port alteration for a radar-only target forward of the beam, except a vessel being overtaken

4

Unless collision risk is ruled out, a fog signal ahead or unavoidable close quarters ahead requires minimum course-keeping speed and, if necessary, all way off

Common Mistakes

Applying the crossing or head-on rules to radar-only contacts

Keeping too much speed after hearing a fog signal ahead

Turning toward a contact that is already abeam or abaft the beam

Test Your Knowledge

Practise this topic and review the explanation for each answer.

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Frequently asked questions about COLREG Rule 19

When does COLREG Rule 19 apply?

Rule 19 applies to vessels not in sight of one another when navigating in or near an area of restricted visibility. There is no stand-on vessel under Rule 19: every ship must assess the situation and manoeuvre prudently.

What speed should a vessel keep in restricted visibility?

Every vessel shall proceed at a safe speed adapted to the prevailing circumstances and conditions of restricted visibility, and a power-driven vessel shall have her engines ready for immediate manoeuvre.

Which course alterations should be avoided in restricted visibility?

So far as possible, avoid an alteration of course to port for a vessel forward of the beam other than for a vessel being overtaken, and avoid an alteration of course towards a vessel abeam or abaft the beam (Rule 19(d)).

What must you do when you hear a fog signal forward of the beam?

Unless risk of collision has been determined not to exist, reduce to the minimum speed for keeping course and, if necessary, take all way off, then navigate with extreme caution until danger of collision is over (Rule 19(e)). The same applies when a close-quarters situation with a vessel forward of the beam cannot be avoided.