Question 1

Match the following situations to their correct fog signal under COLREG Rule 35: (a) power vessel underway making way; (b) power vessel stopped; (c) vessel at anchor; (d) vessel aground.

Accepted Answer

RULE 35 FOG SIGNALS — CORRECT SIGNALS: (a) POWER VESSEL UNDERWAY MAKING WAY (Rule 35a): ONE prolonged blast (4-6 seconds) — every 2 minutes; (b) POWER VESSEL UNDERWAY BUT STOPPED (Rule 35b): TWO prolonged blasts with 2-second interval — every 2 minutes; (c) VESSEL AT ANCHOR (Rule 35g): rapid ringing of bell for approximately 5 seconds — every 1 minute. Vessels of 100m+ ALSO sound a gong aft for 5 seconds after the bell. A vessel at anchor MAY ALSO sound "short-long-short" (Morse R —. — .) as a warning to approaching vessels; (d) VESSEL AGROUND (Rule 35h): three separate bell strokes, THEN rapid ringing of bell for 5 seconds, THEN three separate bell strokes — every 1 minute. This sequence distinguishes a vessel aground from one merely at anchor. ADDITIONAL SIGNALS: sailing vessel under sail — Rule 35c: one prolonged + two short blasts every 2 minutes (this same signal is also used by vessels restricted in ability to manoeuvre, constrained by draught, not under command, and towing/being towed — Rule 35d/e); pilot vessel — Rule 35g: normal fog signal + four short blasts as identity signal. Rule 35 fog signal knowledge is a core OOW examination topic. The key distinctions: making way vs stopped and under way. A vessel "underway but stopped" (engines stopped, no way on but not anchored) sounds TWO prolonged blasts — a different signal from the making-way one prolonged blast. This distinction allows approaching vessels to understand whether there is a collision risk from your movement. The anchor signal (bell): the bell for anchor fog signal is the ship's bell forward. The gong (for vessels 100m+) is sounded aft to indicate the vessel's length and that both ends need to be monitored. The aground signal: three bell strokes BEFORE and AFTER the rapid ring — this distinguishes grounding from anchoring. A vessel that has grounded unexpectedly must immediately sound the aground signal. Pilot vessel fog signal: pilots use the standard fog signal of their type (power vessel if motoring) PLUS the four short blasts identity signal — allowing vessels to identify that a pilot vessel is nearby. Rule 35 also covers: hovercraft, WIG craft, vessels being towed, and other specific situations. The sailing vessel signal (one prolonged + two short) is one of the more commonly confused because it is also used by vessels restricted in their ability to manoeuvre.

Question 2

Visibility drops to 0.5nm on your watch. Summarise the key requirements of COLREG Rule 19 that now govern your conduct.

Accepted Answer

COLREG RULE 19 — CONDUCT IN RESTRICTED VISIBILITY: Rule 19 applies to ANY vessel not in sight of another. Key requirements: (1) RULE 19(b) — SAFE SPEED: proceed at a safe speed adapted to prevailing circumstances and restricted visibility. The vessel must be able to take proper and effective action to avoid collision, and stop within an appropriate distance; (2) RULE 19(c) — RADAR: have due regard to prevailing circumstances, including the limitations of radar equipment; (3) RULE 19(d) — RADAR-ONLY CONTACT: a vessel that detects by radar only another vessel shall determine if a close-quarters situation is developing. If so — take early, substantial avoiding action: (i) an alteration of course to port for a vessel forward of the beam is to be AVOIDED (except when overtaking); (ii) avoid altering course toward a vessel abeam or abaft the beam; (4) RULE 19(e) — SOUND SIGNAL WARNING: if a sound signal is heard apparently forward of the beam and its vessel cannot be seen — reduce to minimum speed or stop. Take all way off if necessary; (5) RULE 35 — FOG SIGNALS: one prolonged blast (4-6 seconds) every 2 minutes when underway making way. Two prolonged blasts (2-second interval) every 2 minutes when underway but stopped. RULE 19 DOES NOT APPLY RULES 11-18 (in-sight rules). There is no give-way/stand-on in restricted visibility. All vessels take action to avoid collision. Rule 19 is one of the most important and most examined COLREG rules. The key distinction: Rules 11-18 apply when vessels are "in sight of one another." Rule 19 applies when they are NOT in sight — specifically in restricted visibility. Rule 19(d)(i) port side restriction: the restriction on altering to port for a vessel forward of the beam is because a vessel approaching from ahead and to your starboard side would be most endangered by a port alteration. Starboard alterations are generally safer because they are the "natural" giving-way direction in most in-sight encounters. Rule 19(e) — sound signal forward of the beam: this is a critical practical requirement. If you HEAR a fog signal from forward of the beam and cannot see the vessel — this is a high-risk situation. The vessel may be very close. Reduce to minimum speed immediately. This is not a recommendation — Rule 19(e) uses the word "shall." The "no give-way/stand-on" point: in restricted visibility, neither vessel knows the other's aspect. The in-sight rules (power/sail, crossing, overtaking) depend on knowing which side you are approaching from. In fog, this cannot be determined — hence Rule 19 replaces them all.

Question 3

You are in fog and hear a fog signal apparently from fine on the starboard bow, but ARPA shows nothing. The signal is heard again. What do you do?

Accepted Answer

FOG SIGNAL HEARD — ARPA NO CONTACT — ACTION: RULE 19(e): if a sound signal is heard apparently forward of the beam but its vessel cannot be seen — REDUCE TO MINIMUM STEERAGE SPEED or take all way off. If necessary to avoid collision, stop. This rule is absolute — the hearing of a forward fog signal requires immediate speed reduction. WHY ARPA SHOWS NOTHING: radar targets forward of the beam with no ARPA contact — possible causes: (1) Small vessel below ARPA detection threshold (wooden fishing vessel, FRP hull, small yacht); (2) Radar shadow: an obstruction (another vessel, land mass) may be masking the contact; (3) Sea clutter masking a small target; (4) Fog signal from a vessel that is nearly stern-on (very small radar cross-section); (5) ARPA acquisition delay: a newly appearing target may take 3 minutes to establish a track — it would show as a raw radar return but not yet have a track. IMMEDIATE ACTIONS: (1) REDUCE SPEED to minimum steerage NOW — do not wait for ARPA to confirm; (2) CALL MASTER — fog signal with no ARPA contact is a high-risk situation; (3) POST BOW LOOKOUT: send someone to the bow to listen — the ears can often determine direction better than the bridge speaker; (4) SOUND OWN FOG SIGNAL — ensure the other vessel can locate you; (5) EXTRA VIGILANCE on radar — manually scan for any paint. This scenario is designed to test knowledge of Rule 19(e) and ARPA limitations. Rule 19(e) requires action on hearing a forward fog signal even without radar contact. The word "shall" makes this mandatory. ARPA limitations in fog: ARPA is excellent but it has real-world detection limits. A small wooden fishing vessel with limited radar reflectivity may not show on radar at close range in heavy rain clutter or sea clutter. Yet a fishing vessel has a fog signal requirement (one prolonged blast + two short blasts if motor vessel, one prolonged + two short if fishing). Sound propagation in fog: sound can travel significantly further in fog than in clear weather because of atmospheric temperature inversion. The fog signal you hear may be from a vessel 3-5nm away — or it may be from 0.5nm away. You cannot know without ARPA or visual confirmation. Option C (turn toward the sound): this violates Rule 19(d)(i) if the vessel is forward of the beam — you should not turn toward an unidentified vessel in fog. Heading into the sound source is potentially heading into the collision. The bow lookout: sending an experienced officer or AB to the bow as a sound lookout is excellent practice in fog — they can hear direction and distance better than the bridge sound systems, especially with background engine/machinery noise.