524. If the speed necessary for reaching port at a designated time is 16.8 knots and the pitch of the propeller is 22.3 feet, how many revolutions per minute will the shaft have to turn, assuming a 4% negative slip?

The shaft will have to turn at approximately 73 revolutions per minute. This is calculated by first determining the theoretical pitch speed based on the 4% negative slip, then using that speed and the propeller pitch to solve for the required RPM.