279. The propeller on a vessel has a diameter of 24.0 feet and a pitch of 21.3 feet. What would be the slip if the vessel cruised 510 miles in a 24 hour day (observed distance) at an average RPM of 86?

The propeller slip is calculated as (Theoretical distance — Actual distance) / Theoretical distance * 100. Given the observed distance of 510 nautical miles, a propeller pitch of 21.3 feet, and an RPM of 86, the slip is approximately -17.5%, indicating the vessel traveled farther than predicted by the propeller's pitch alone.