Radar-Only Crossing in Restricted Visibility
M/V Atlantic Dawn, a 12,000 GT container ship, is eastbound in the English Channel TSS at 16 kn in fog with visibility 0.8 nm. Radar and ARPA show a target at 8 nm, bearing 20° on the starboard bow, speed 18 kn, crossing from starboard to port. CPA is 0.4 nm and TCPA 12 minutes. The target is not answering VHF channel 16. No fog signal has been heard from the target. Own vessel is in the eastbound lane and the target appears to be crossing the lane. The OOW has a helmsman and a lookout on the bridge. The master is asleep.
1. Under the COLREGs, what is the situation and what action is required?
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This is a restricted-visibility situation under Rule 19. There is a risk of collision because CPA is 0.4 nm and TCPA is 12 minutes. Rule 19 overrides the crossing rule: neither vessel is stand-on. Own vessel must take avoiding action in ample time and, so far as possible, avoid altering course to port for a target forward of the beam. The target is on the starboard bow crossing from starboard to port, so a substantial alteration to starboard is appropriate to pass astern. A reduction of speed is also required because visibility is 0.8 nm and the target is not responding. Do not rely on VHF. Sound the fog signal.
2. How should the OOW execute and monitor the manoeuvre?
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Alter course to starboard by at least 30–40° and reduce speed to about 8 kn. Monitor the ARPA: CPA should increase and the target should move aft. If the target remains on a constant bearing and CPA continues to fall, take further action, including full astern. Keep the helmsman informed, use the lookout, and switch to manual radar plotting if needed. Do not alter to port. Avoid a series of small alterations. If the target is detected visually at close range, take immediate action to avoid collision.
3. What documentation and notifications should be made?
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Call the master immediately. Log the time, target data, alteration, and speed. Make the appropriate fog signal and listen for the target's signal. Report to VTS if required by local rules. After passing, resume course and speed only when clear. Complete a near-miss report. Do not use VHF for collision avoidance beyond informational calls; the COLREGs action must stand on its own.