Dusk, Fog and the Wrong Side of the Channel
Priya is riding her PWC back to the ramp at 5:40 pm in late autumn. Visibility is dropping; a bank of fog is rolling in from the east and the far shoreline is already indistinct. She is in a narrow channel marked by red and green lateral marks, travelling upstream with the flood tide. Her speed is about 25 knots, which she considers cautious because the posted limit in the area is 30 knots. A larger half-cabin cruiser is coming the other way, and Priya has drifted to the right-hand side of the channel to give herself room from a moored houseboat. She has no navigation lights fitted and is relying on being seen. The cruiser sounds one short blast. Priya does not know what it means and holds her course and speed. The cruiser turns sharply and passes close enough that Priya feels its wake.
1. Was Priya keeping a proper lookout and a safe speed? Explain the standard that actually applies, not just the number on the sign.
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Speed. The posted 30-knot limit is a ceiling, not a target. The collision regulations require every vessel to proceed at a safe speed having regard to visibility, traffic density, manoeuvrability and stopping distance. In fog with the shoreline already indistinct, 25 knots is not cautious - it is close to the limit in conditions where the limit is beside the point. A PWC has no brakes; stopping distance at 25 knots is measured in tens of metres, and reaction time eats most of the visibility she has left. The correct answer is a speed from which she could stop within the distance she can actually see, which in this fog is a fraction of 25 knots.
Lookout. A proper lookout means using sight and hearing and all available means, continuously. Priya was looking at the houseboat and the channel edge, not scanning ahead. She also had no lights, so she was relying entirely on being seen by others - the inverse of keeping a lookout.
Channel position. Travelling upstream with the flood tide in a narrow channel, she should keep to the starboard (right) side of the channel as far as is safe and practicable. Drifting right to avoid the houseboat is defensible, but she must not let that push her into the path of oncoming traffic without checking first.
The lesson. The exam will give you a compliant speed limit and an unsafe speed in the same sentence. Always answer the safe-speed question, not the sign question.
2. The cruiser sounded one short blast. What did it mean, and what should Priya have done?
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Meaning. One short blast means 'I am altering my course to starboard' - the cruiser was telling Priya it intended to turn to its right. Two short blasts would mean altering to port, three short blasts means operating astern propulsion, and five or more rapid blasts means doubt or danger.
What Priya should have done. First, she should have understood the signal and predicted the cruiser's movement rather than holding course blindly. Second, because she was uncertain, she should have sounded five or more rapid blasts to signal her doubt and taken early and substantial action to keep clear. Third, she should have reduced speed immediately - in fog, the safest response to an unclear crossing situation is to slow down and, if necessary, stop and let the other vessel's intentions resolve.
The deeper failure. Priya's real error was not the missed signal; it was that she had no lights, was travelling fast in fog, and had no plan for meeting an oncoming vessel in a narrow channel. By the time the blast was sounded, her options were already poor. The exam-style reasoning is: identify the signal, then identify the earliest point at which the situation could have been made safe. That point was at the fog bank, not at the blast.
Practical rule. If you do not know what a signal means, assume the other vessel is manoeuvring and act to keep clear. Holding course and speed because you are unsure is the one response that is always wrong.