Patrol Boat Allocation With Limited Fuel
A coastal station has two interceptor boats, B1 and B2. B1 is serviceable with 600 litres of fuel, consuming 60 litres per hour at patrol speed. B2 has an engine fault and can run only at reduced speed, consuming 40 litres per hour, with 320 litres available. A radar contact suggests a suspicious vessel will cross a channel 90 nautical miles from base. B1 makes 30 knots at patrol speed; B2 makes 20 knots. Both boats must return to base and cannot refuel at sea. A third boat from a neighbouring station can reach the channel in 5 hours if requested, but the request takes 1 hour to process and commits the station to a written justification.
1. Calculate the maximum time each boat can remain on task and determine whether either can reach the channel, patrol, and return.
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B1: fuel endurance is 600 ÷ 60 = 10 hours of running. Transit to the channel is 90 ÷ 30 = 3 hours, and return is another 3 hours, so 6 hours are consumed in transit, leaving 4 hours on station.
B2: fuel endurance is 320 ÷ 40 = 8 hours of running. Transit is 90 ÷ 20 = 4.5 hours each way, totalling 9 hours, which exceeds its 8-hour endurance. B2 cannot reach the channel and return even with zero time on station. It must not be tasked beyond a point from which it can return: its safe radius is 4 hours of running outbound at 20 knots, that is 80 nautical miles, short of the 90 required.
So only B1 can cover the channel, with a maximum of 4 hours on station before it must turn back. B2 is useful only for closer patrol lines.
2. Recommend a deployment plan, including whether to request the neighbouring boat, and state the margin of safety you are keeping.
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B1 should proceed to the channel and be tasked for no more than 3 hours on station, preserving 1 hour of fuel endurance as reserve for weather, a chase, or slower return speed. Fuel plans that consume the entire endurance are unsound because consumption rises with speed and sea state.
B2 should patrol a line within 60 nautical miles of base, giving 3 hours outbound, 3 hours return, and 2 hours of endurance in hand.
The neighbouring boat should be requested. Processing takes 1 hour and transit 5 hours, so it arrives about 6 hours from now, which is after B1's window closes. It therefore does not substitute for B1 but provides continuity if the contact persists, and it creates a second asset if the vessel turns along the coast. The written justification is a routine administrative cost, not a reason to decline.
The plan should be logged with times, fuel figures, and the reserve retained, so that the decision is defensible afterwards.