While steaming at 15.5 knots, your vessel consumes 333 barrels of fuel oil per day. In order to reduce consumption to 176 barrels of fuel oil per day, what is the maximum speed the vessel can turn for?

Correct Answer: Option C — 12.5 knots

Fuel consumption varies approximately with the cube of the speed according to Bowditch principles. Applying the fuel-speed formula, $V_2 = V_1 \times \sqrt[3]{F_2 / F_1}$, yields $15.5 \times \sqrt[3]{176 / 333}$, giving a maximum speed of 12.5 knots.