Outbound Kuryk in Fog: Two Contacts in a One-Way Channel
At 0340 a 6,500 GT tanker is outbound from Kuryk at 11 kn in a dredged channel 180 m wide. Visibility is 1.2 nm in mist and radar is on the 1.5 nm scale. On the north side a dredger shows three all-round lights in a vertical line, red over white over red, and two reds over two greens facing the channel. Ahead, 5° on the starboard bow at 1.0 nm, a radar contact closes slowly with a CPA of 0.15 nm; a second contact at 1.4 nm dead ahead carries a steady bearing and shows green over white. The channel gives 0.9 m of under-keel clearance and the banks are not safe to leave. A 1.5 kn current sets across the channel, and the master wants to hold 11 kn to keep steerage way. The fog signal is being made automatically and the ARPA has not been tuned since the last watch.
1. Identify what each light configuration means and state who must keep out of whose way, and what your own sound signal must be.
Read the worked answer
Red over white over red, all-round, is a vessel restricted in her ability to manoeuvre (Rule 27(b)), and it is reinforced by the two all-round reds over two all-round greens of a dredger showing an obstruction: the red side is the obstructed side and the green side is where it is safe to pass. The channel-facing side is green, so the passage past the dredger stays on that side - towards the south of the channel in this case, and the dredger's position must be plotted, not assumed from one look.
Green over white on the second contact is a vessel engaged in trawling (Rule 26(b)).
The order of responsibility under Rule 18 is clear: a power-driven vessel underway keeps out of the way of a vessel restricted in her ability to manoeuvre and of a vessel engaged in fishing; a vessel engaged in fishing keeps out of the way of a vessel restricted in her ability to manoeuvre. So the dredger is effectively the fixed constraint, the tanker must keep clear of it, and both the trawler and the tanker must keep clear of each other - which is exactly the situation that needs early, unambiguous action rather than mutual assumption.
Own signal: making way through the water in restricted visibility, one prolonged blast at intervals of not more than 2 minutes (Rule 35(a)). If the ship stops and has no way, two prolonged blasts with a 2-second interval between them (Rule 35(b)), and the fog signal must be sounded manually if the automatic unit's timing is in doubt.
2. Both contacts are closing with little or no bearing drift. Evaluate the situation and decide what you actually do, given the channel limits and the current.
Read the worked answer
In restricted visibility Rule 19 governs, not the steering rules of Part B sections I–III: there is no right-of-way, only a duty to proceed at a safe speed, have engines ready for immediate manoeuvre, and take avoiding action in good time. 11 kn with 1.2 nm visibility and a 0.15 nm CPA is not a safe speed.
The head-on contact is the priority. Steady bearing, decreasing range, only 1.4 nm ahead: risk of collision is established under Rule 7, and the ship cannot alter far to starboard because the dredger occupies the north side and the bank is 0.9 m UKC away. Rule 19(d) forbids turning to port for a vessel forward of the beam and forbids turning towards a vessel abeam or abaft - so the textbook starboard turn is not available in this width. The remaining correct action is to reduce speed progressively to steerage way, engine ready to stop, and be prepared to take all way off and hold clear; a stopped ship with the current setting her across the channel must be anticipated with helm and, if necessary, a touch of power.
For the starboard-bow contact, reduce speed first; if it still closes, a small starboard alteration may be possible but only within the channel, and it must be substantial enough to be seen on radar, not a series of nibbles.
Before any of this: tune the ARPA (gain, sea and rain clutter), switch to a shorter range, plot both contacts by hand as a cross-check, and call the master. VHF identification on channel 16 ('the vessel showing green over white ahead of me at ...') may assist, but the agreement must not contradict the Rules and must never replace them.
3. What do you record and report, and what would make you stop the passage entirely?
Read the worked answer
Record in the bridge log and bell book: time and method of each radar fix; tuning state of the ARPA; every contact's first range and bearing, subsequent plots and CPA/TCPA; every sound signal; each engine order and the ship's speed through the water; the VHF calls made, to whom and with what result; the times the master was called and his orders; the dredger's lights and position as observed. The record should read as a timeline a third party can follow.
Report: inform port control of the dredger's position and the channel state, and ask whether the channel is clear of the trawler's gear; if the fog signal unit failed or the ARPA is defective, that goes into the defect list, not just the log.
Stop the passage if: the contacts cannot be resolved by 0.5 nm and there is no width to manoeuvre; the vessel cannot be held in the channel at steerage way against the 1.5 kn cross-current; the echo sounder shows depths approaching the 0.9 m UKC; the dredger's green side is not where the chart or notice says it is; or visibility falls below the point where a 180 m channel can be kept by radar and visual reference. In any of those cases the answer is to bring up, hold clear of the channel and wait - an anchored or hovering tanker costs hours, a grounding in a dredged cut costs the ship.