Conduct and steering-and-sailing rules
The conduct rules apply in any visibility: a proper lookout (5), a safe speed (6), a full appraisal of risk by all means including radar (7, with its warning against scanty-information assumptions), and action that is positive, early, obvious and checked (8). In sight of one another the head-on, crossing and overtaking rules (13-15) apply, with the give-way and stand-on duties (16-17) and the pecking order of Rule 18. The Master applies them with judgement and seamanship, giving way early and boldly, holding on where required but acting if the other vessel does not.
Restricted visibility, lights and signals
Under Rule 19 in restricted visibility there is no stand-on vessel; both proceed at a safe speed and avoid a close-quarters situation, and a vessel avoids altering to port for a vessel forward of the beam. The Master recognises vessels by their lights and shapes — the vertical patterns for not-under-command, restricted-in-ability, constrained-by-draught, at anchor, and so on — and knows the manoeuvring and fog signals of Rules 34 and 35. The examiner expects the rules cold and applied with the reasoning of a seaman.
WARNING — Early, large, obvious — and check At command level the examiner expects the seamanship as well as the rule: an alteration to starboard that is early and unmistakable, followed by a check that the other vessel is drawing clear, as Rule 8 requires.
NOTE — Restricted visibility removes the stand-on vessel Do not apply the in-sight give-way/stand-on logic in the fog. Under Rule 19 both vessels navigate with caution by radar, reduce to a safe speed, and avoid close-quarters; there is no right of way.