The observed distance for a day's run was 302.7 miles. The propeller had a pitch of 20'06", and the average RPM was 67. What was the slip?

Correct Answer: Option D — +7.0%

Pitch of 20'06" equals 20.5 feet. Engine distance: (67 * 1440 * 20.5) / 6076.1 = 325.5 miles. Slip: (325.5 - 302.7) / 325.5 = 0.070, or +7.0%. Positive slip indicates the vessel is traveling slower than the propeller's theoretical advance, common in heavy weather or fouled hull conditions.