172. The propeller on a vessel has a diameter of 20.6 feet and a pitch of 23.4 feet. What would be the apparent slip if the vessel cruised 538 miles in a 24 hour day (observed distance) at an average RPM of 87?

The apparent slip is calculated by comparing the theoretical distance traveled based on propeller pitch and RPM to the actual distance traveled. In this case, the actual distance (538 nautical miles) exceeds the theoretical distance (approximately 482 nautical miles), resulting in an apparent slip of -11.6%.