The propeller on a vessel has a diameter of 23.7 feet and a pitch of 24.8 feet. What would be the apparent slip if the vessel cruised 442 miles in a 23 hour day (observed distance) at an average RPM of 89?
A. -7.8%
B. +7.8%
C. -11.8%
D. +11.8%
ANSWER ''D''
Distance 442miles divided by 23hrs = 19.2 kts
Speed x 6080 divided by Pitch x RPM x 60 =
19.2 kts x 6080 divided by 24.8 x 89 x 60 = .88 (1.00 - .88 = +12.0%
