Conduct of Vessels in Restricted Visibility

No. Rule 19 applies to vessels not in sight of one another, and the give-way and stand-on roles in Rules 15 through 17 apply only to vessels in sight of one another. In fog neither vessel may rely on the other holding course and speed — both are obliged to take action to avoid collision. Exam questions that offer 'the other vessel is the stand-on vessel' as an option in restricted visibility are testing exactly this.

Rule 19(d) tells a vessel acting on radar information alone to avoid, so far as possible, altering course to port for a vessel forward of the beam unless that vessel is being overtaken. The reason is practical: in a meeting or crossing situation a port turn steers into the water the other vessel is most likely to occupy if she makes the conventional starboard alteration, converting a passing situation into a collision. The same paragraph also warns against altering course toward a vessel abeam or abaft the beam.

33 CFR §83.03(l) defines it as any condition in which visibility is restricted by fog, mist, falling snow, heavy rainstorms, sandstorms, or any other similar causes. Read the definition carefully, because it is written about the condition and not about the observer: an option describing a lookout who has mislaid their glasses, a large vessel that cannot make out a smaller one, or condensation on the wheelhouse windows is describing something else, however plausible it sounds. Darkness is not restricted visibility either — night is dealt with by the lights of Part C. The list ends with 'any other similar causes', so smoke, haze, blowing spray and volcanic ash all qualify on the same footing as fog.

Rule 19 sets the conduct; the signals themselves are in Rule 35 (33 CFR §83.35), and they are sounded in or near an area of restricted visibility by day as well as by night. A power-driven vessel making way sounds one prolonged blast at intervals of not more than 2 minutes. Underway but stopped and making no way through the water, she sounds two prolonged blasts about 2 seconds apart, at the same interval. The vessels in §83.35(c) sound one prolonged followed by two short blasts instead, and a manned towed vessel — the last of the tow, if more than one is towed — sounds one prolonged followed by three short. A vessel at anchor rings her bell rapidly for about 5 seconds at intervals of not more than 1 minute; at 100 metres or more the bell is sounded forward and a gong is then sounded rapidly for about 5 seconds aft. A vessel aground gives that bell signal and adds three separate and distinct strokes on the bell immediately before and after the rapid ringing. Two exemptions are worth memorising: a vessel of 12 metres or more but under 20 metres need not give the bell signals, and a vessel under 12 metres need not give any of them — but either way she must make some other efficient sound signal at intervals of not more than 2 minutes. A pilot vessel on pilotage duty may add an identity signal of four short blasts.

This is the exam question where the two rulebooks part company, so read the citation on the stem. Under the Inland Rules, 33 CFR §83.35(c) lists five: a vessel not under command; a vessel restricted in her ability to maneuver, whether underway or at anchor; a sailing vessel; a vessel engaged in fishing, whether underway or at anchor; and a vessel engaged in towing or pushing another vessel. Under COLREGs, Rule 35(c) lists those same vessels and adds a sixth — a vessel constrained by her draught. She is absent from the Inland list because the Inland Rules have no constrained-by-draught vessel at all: there is no Inland Rule 28, and the Inland numbering runs straight from Rule 27 to Rule 29. The other half of the difference is where the at-anchor cases live. COLREGs gives them their own paragraph, Rule 35(d), under which a fishing vessel at anchor and a vessel restricted in her ability to manoeuvre carrying out her work at anchor sound the 35(c) signal rather than the anchor signal; Inland §83.35(d) is [Reserved] and reaches the same result by writing 'whether underway or at anchor' into (c) itself. A vessel at anchor with none of those characteristics does not sound this signal — she rings her bell.

It is the minimum speed at which the vessel can still be kept on course — enough water flow over the rudder to steer, and no more. Rule 19(e) requires that speed on hearing a fog signal apparently forward of the beam or when a close-quarters situation forward of the beam cannot be avoided, and requires taking all way off if necessary. The rule then requires navigating with extreme caution until the danger of collision is over.

Yes. Seeing a target on radar is not being 'in sight of one another' — Rule 3 defines that as being visually observed. A vessel tracked on radar in fog is still a Rule 19 case, which is why 19(d) is written specifically for action taken on radar information alone.

No. 33 CFR 83.19 carries the same requirements as COLREGs Rule 19, so this is one of the rules where the two rulebooks agree and an answer correct under one is correct under the other. Candidates sometimes expect a difference because so much of Part D diverges between the rulebooks; here it does not.