505. The propeller on a vessel has a diameter of 18.8 feet and a pitch of 21.4 feet. What would be the slip if the vessel cruised 378 miles in a 24 hour day (observed distance) at an average RPM of 76?

The vessel's slip is +1.9%. This is because the observed distance (378 nautical miles) is less than the theoretical distance calculated from the propeller's pitch and RPM (approximately 385.4 nautical miles), indicating the propeller advanced less than its theoretical potential.