You have steamed 504 miles at 21 knots and burning 633 barrels of fuel per day. You must decrease your consumption to 410 barrels per day with 399 miles left in your voyage. What must you reduce your speed (kts) to in order to burn this amount of fuel?

Correct Answer: Option B — 19.0

Vessel fuel consumption and speed follow the cubic law, stating that fuel consumption per distance is proportional to the square of the speed. Applying this hydrodynamic principle determines the reduced speed required for the remaining voyage.