Question 1

How do you define a "close-quarters situation" in restricted visibility and at what point must you take avoiding action?

Accepted Answer

CLOSE-QUARTERS SITUATION — DEFINITION AND ACTION TIMING: COLREG does not define "close-quarters situation" numerically — it is a judgement call based on circumstances. GENERAL GUIDANCE: a close-quarters situation exists when, if present courses and speeds are maintained, there will be insufficient sea-room and time to take effective action to avoid collision. PRACTICAL INDICATORS: (1) CPA FALLING BELOW DEFINED LIMIT: most companies define a "close-quarters zone" in SMS — typically 1-2nm in open sea, 0.3-0.5nm in coastal waters. When CPA drops below this, a close-quarters situation is developing; (2) TCPA DECREASING: combined with small CPA — the time available for action is reducing; (3) VESSEL BEARING DRAWING FORWARD: if bearing is steady and range is decreasing — classic collision course (Constant Bearing Decreasing Range — CBDR); ACTION TIMING — COLREG RULE 19(d): "take action to avoid close-quarters situation... in ample time." The word "ample" is critical — not "at the last moment." Action taken late (when the vessel is 0.5nm and closing fast) may be insufficient. Action taken at 2nm CPA declining with TCPA 10 minutes gives ample time for a large, visible alteration. THE TIMING PRINCIPLE: act EARLY, act LARGE. A 30° course alteration at 2nm is vastly preferable to a 60° alteration at 0.5nm. Early action is also clearly visible on the other vessel's ARPA — an important collision avoidance signal. The "close-quarters situation" concept: central to COLREG but deliberately undefined numerically. This allows masters and OOWs to apply it to their specific circumstances — vessel size, sea state, traffic density, visibility. The CBDR (Constant Bearing Decreasing Range) principle: if a radar target maintains a constant bearing while its range decreases — it is on a collision course with your vessel. This is the fundamental radar collision detection principle, known since early radar use. "Ample time" in Rule 16 (and Rule 19): action taken in "ample time" means action taken far enough in advance that: (a) the action is effective at the time you take it; (b) the action is detectable by the other vessel's radar or visually. A late, desperate course alteration in restricted visibility when vessels are 0.3nm apart may be too late and may not be seen by the other vessel's radar before impact. The company CPA limit: most oil major and major shipping company SMSs specify a minimum CPA (e.g., "maintain minimum CPA of 1.0nm in open sea, 0.5nm in coastal waters"). These are company rules that supplement COLREG. They exist to prevent OOWs from "testing" what close-quarters means in practice.

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.