While steaming at 13.5 knots, your vessel consumes 251 barrels of fuel oil per day. In order to reduce consumption to 129 barrels of fuel oil per day, what is the maximum speed the vessel can turn for?

Correct Answer: Option A — 10.8 knots

Per Bowditch navigation standards, fuel consumption changes cubically with speed. Multiplying the initial 13.5 knots by the cube root of the fuel ratio ($129 / 251$) accurately calculates the reduced maximum speed to 10.8 knots to achieve the target daily consumption.