590. You are steaming at 22 knots and burning 319 barrels of fuel per day. You must decrease your consumption to 137 barrels per day. What must you reduce your speed to in order to burn this amount of fuel?

Fuel consumption is proportional to the cube of speed; therefore, the new speed is calculated by multiplying the original speed by the cube root of the ratio of the new fuel consumption to the original fuel consumption, resulting in a speed of 16.6 knots.