Question 1

You are transiting the Dover Strait TSS in fog with 0.8nm visibility. Describe the specific additional precautions you take compared to clear weather.

Accepted Answer

TSS IN FOG — ADDITIONAL PRECAUTIONS: (1) REDUCED SPEED: reduce to safe speed — stopping distance must not exceed 0.8nm. At 12+ knots, you cannot stop within 0.8nm; recommend 6-8 knots at most; (2) MASTER ON BRIDGE: call master immediately. Dover Strait is one of the world's busiest waterways — master must be present in fog; (3) FOG SIGNALS: one prolonged blast every 2 minutes from the moment visibility becomes restricted; (4) ARPA ON: full ARPA utilisation — all significant targets tracked. Two ARPA displays if available — 6nm tactical and 12nm strategic; (5) MANUAL STEERING: disengage autopilot — manual helm for immediate response; (6) BOW LOOKOUT: extra lookout on bow; (7) VHF: monitor Ch 16 AND Ch 11 (Dover VTS working channel). Advise Dover Coastguard of reduced visibility on request or if warranted; (8) DOVER VTS: the Vessel Traffic Service monitors all traffic. They will manage separation — but do NOT rely on VTS to do your collision avoidance; (9) NAVTEX/AIS: monitor for NAVTEX hazard warnings; monitor AIS for all TSS traffic; (10) NAVIGATION: maintain position accurately within the traffic lane — straying into the separation zone or oncoming lane in fog is extremely dangerous; (11) RULE 10 COMPLIANCE: maintain TSS procedures (correct lane, correct direction, crossing at right angles if crossing) even in fog; (12) ENGINE ON IMMEDIATE NOTICE: engines on standby for immediate speed change. Dover Strait TSS: among the busiest navigation choke points in the world. Approximately 500 vessel transits per day. In fog, this is an extreme navigation challenge. VTS reliance trap (option B): VTS is a service, not a safety guarantee. VTS cannot ensure your vessel avoids collision — they provide information and may give advice, but collision avoidance remains the master's and OOW's responsibility. This is clearly stated in the IALA VTS Manual. Anchoring in Dover TSS (option C): Rule 10(h) says you SHOULD NOT anchor in a TSS if it can be avoided. The Downs anchorage east of the Strait is the appropriate waiting area. Anchoring IN the TSS lane is extremely dangerous — passing traffic would encounter an anchored vessel in their lane. Same-direction traffic (option D): the TSS separates opposing traffic, but within a lane, not all vessels are going the same speed. A slow vessel being overtaken by a faster vessel in fog creates risk. Vessels crossing the TSS, vessels leaving/joining the lane — all create collision scenarios within the TSS. The 2 radar display strategy: experienced navigators in Dover Strait fog use one radar on 3-6nm to monitor immediate traffic and one on 12-24nm to identify developing conflicts early. The strategic display allows heading changes to be planned well before the tactical situation becomes critical.

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

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.