In fog a target is detected by radar alone, forward of the beam. Which manoeuvre is barred?
An alteration to port for a vessel forward of the beam (other than one being overtaken). Also altering towards a vessel abeam or abaft the beam.
Rule 19 (d).
Part of the convention In fog: you cannot see each other
This applies to vessels not in sight of one another when navigating in or near an area of restricted visibility. Proceed at a safe speed for those conditions and, if power-driven, keep your engines ready for immediate manoeuvre.
- If you detect another vessel by radar alone, determine whether a close-quarters situation is developing or risk of collision exists, and take avoiding action in ample time. If the action is an alteration of course, avoid an alteration to port for a vessel forward of the beam (other than one being overtaken) and an alteration towards a vessel abeam or abaft the beam.
- Except where it has been determined that a risk of collision does not exist: if you hear a fog signal apparently forward of your beam, or cannot avoid a close-quarters situation with a vessel forward of the beam, reduce your speed to the minimum at which you can be kept on course, and if necessary take all your way off and navigate with extreme caution until the danger is over.
At sea it looks like this
In fog a radar target is fine on your port bow. The instinct to turn to port and pass astern of her is barred: she may herself be turning to starboard, as vessels do when meeting head on, and you would meet. Turn to starboard and take off speed instead.
The rule says«…every vessel which hears apparently forward of her beam the fog signal of another vessel… shall reduce her speed to the minimum at which she can be kept on her course.»
Check yourself
In fog you hear a fog signal apparently forward of your beam. What must you do?
Reduce speed to the minimum at which you can be kept on course, take all your way off if necessary, and navigate with extreme caution until the danger is over.
Rule 19 (e).
What is required of the engines in restricted visibility?
A power-driven vessel keeps her engines ready for immediate manoeuvre and her speed safe for the conditions.
Rule 19 (b).