Stand-On in a Traffic Lane with a Give-Way Vessel That Holds Course
At 0240 you are the OOW on a 200 m bulk carrier making 14 knots on 000 deg (T) by autopilot, in the northbound lane of a traffic separation scheme off a major North European port. Visibility is 3 nm in clear air on a dark night, no moon. A 95 m coaster bears 045 deg (T) at 6 nm; the ARPA shows a constant bearing with range reducing 1 nm every 6 minutes - she is making 9 knots on 270 deg (T). There is no indication that she is altering. A fast ferry is overtaking 4 nm astern, making 19 knots on 005 deg (T). The lane boundary is 0.6 nm to port, with an inshore traffic zone beyond it containing several fishing vessels. Your turn rate at 14 knots is about 2 deg per second at hard-over. At 0252 she bears 045 deg at 4 nm, still holding course and speed; the master must be called at 3 nm under the ship's bridge procedures.
1. Establish who gives way, what your obligations are as stand-on, and by when things must happen.
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Bearing steady at 045 deg with range closing 10 knots means the relative track is straight at you: risk of collision exists under Rule 7 and must be treated as such well before it is visually obvious. From her position she sees you bearing 225 deg, that is 45 deg on her port bow, so under Rule 15 she is the give-way vessel and must keep out of your way, taking early and substantial action under Rule 8.
You are the stand-on vessel. Rule 17(a)(i) requires you to keep your course and speed, which is also what her bridge team is entitled to expect. Your duties in the meantime are active, not passive: plot at short intervals, watch the bearing trend rather than a single reading, run an ARPA trial manoeuvre so that an alternative is already worked out, keep the overtaking ferry plotted, and confirm the lane boundary position.
Timing: at 6 nm and 10 knots closing you have about 36 minutes. At 4 nm you have about 24 minutes, which is late but not yet in extremis. That is the moment to sound at least five short and rapid blasts under Rule 34(d) and, if needed, a light signal under Rule 36 to attract attention - and to call the master. Note that 3 nm visibility at night in clear air is not restricted visibility under Rule 3(l), so Part B Section II applies, not Rule 19. A VHF call to her is a supplement, never a substitute for the Rules.
2. At 4 nm she still holds course and speed. What action do you take, is a turn to port permitted, and how does the overtaking ferry constrain you?
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Rule 17(a)(ii) allows the stand-on vessel to act as soon as it is apparent the give-way vessel is not taking appropriate action - 4 nm at 10 knots closing qualifies.
Is port permitted? Rule 17(c) prohibits a course alteration to port only for a vessel on your own port side. She is on your starboard side, so a port turn is not prohibited. Permitted is not the same as prudent: port takes you across the lane, 0.6 nm from the boundary, towards the fishing vessels in the inshore zone; it puts your starboard quarter towards a ferry closing at 5 knots overtaking speed; and it is the opposite of what the coaster's officer will instinctively do if he wakes up and turns to starboard.
The cleanest action is a substantial reduction in speed - come down through half ahead to slow ahead or stop - which lets her cross ahead, needs no lane deviation, keeps you clear of the ferry's track and is immediately visible in her ARPA and in your sound signals. Hold a bold alteration to starboard in reserve if she turns to port. Whatever you choose, make it early, obvious and single; a series of small alterations is the classic way to turn a close-quarters situation into a collision. Call the master, and use the VHF only to state your intention clearly and confirm hers.
3. The coaster answers on VHF that she is 'constrained by draught' and expects you to give way. Is she right, and how do you handle the exchange?
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She is not right, or at least not right enough to rely on. Rule 3(g) defines a vessel constrained by her draught narrowly: by reason of her draught in relation to the available depth and width of navigable water she is severely restricted in her ability to deviate from the course she is following. A 95 m coaster at 9 knots in a deep, wide traffic lane does not normally meet that test. Even where the status is genuine, it does not confer right of way: Rule 18(d) requires other vessels, if the circumstances admit, to avoid impeding her safe passage, but a crossing vessel remains the give-way vessel under Rule 15. Nor does the traffic scheme give anyone priority - Rule 10(l) states that the Rule does not relieve any vessel of her obligations under any other Rule.
Handling: reply factually and briefly - your course and speed, your assessment that she is the give-way vessel, and a clear statement of what you intend to do. Ask her intention and get an unambiguous agreement; if she will not commit, act on the Rules and your own plot. Then keep plotting: a VHF agreement does not override the Rules and is no defence if it fails, and many collisions have been preceded by a polite, mutually misunderstood radio conversation.
Record the time, the position, the vessel, the content of the exchange and your actions in the bridge notebook and on the VDR, inform the master, and report it through the company's near-miss system afterwards.