While steaming at 19.4 knots, your vessel consumes 392 barrels of fuel oil per day. In order to reduce consumption to 182 barrels of fuel oil per day, what is the maximum speed the vessel can turn for?

Correct Answer: Option A — 15.0 knots

Fuel consumption varies as the cube of the speed per standard marine engineering cubic law: Fuel2 / Fuel1 = (Speed2 / Speed1)^3. Solving for the reduced fuel consumption target of 182 barrels from an initial 392 barrels at 19.4 knots yields a maximum speed of 15.0 knots.