You must average 16.25 knots to reach port at a designated time. Your propeller has a pitch of 21'08", and you estimate 4% negative slip. How many revolutions per minute must you average to arrive on time?

Correct Answer: Option C — 73 RPM

Calculate required RPM using: RPM = (Speed × 6076.1) / (Pitch × 60 × (1 - Slip)). With 16.25 knots, 21.67-foot pitch, and -4% slip (1.04), the math yields 73 RPM. Negative slip implies the vessel is outperforming the theoretical propeller speed, requiring fewer revolutions to maintain the target speed.