If the speed necessary for reaching port at a... - USCG Navigation Problems

If the speed necessary for reaching port at a designated time is 16.8 knots and the pitch of the propeller is 22.3 feet, how many revolutions per minute will the shaft have to turn, assuming a 4% negative slip?

A 66

B 73

C 61

D 80

AI Explanation

The correct answer is B) 73 revolutions per minute. To arrive at this answer, we need to use the formula for propeller revolutions per minute (RPM): RPM = (Speed in knots x 1.688) / (Propeller pitch in feet x (1 - Slip percentage)) Given information: - Speed required: 16.8 knots - Propeller pitch: 22.3 feet - Slip percentage: 4% (or 0.04) Plugging these values into the formula: RPM = (16.8 x 1.688) / (22.3 x (1 - 0.04)) RPM = 28.3 / (22.3 x 0.96) RPM = 28.3 / 21.408 RPM = 73 (rounded to the nearest whole number) The other options are incorrect because they do not correctly apply the formula or account for the given 4% negative slip.

Question 115Navigation Problems

If the speed necessary for reaching port at a designated time is 16.8 knots and the pitch of the propeller is 22.3 feet, how many revolutions per minute will the shaft have to turn, assuming a 4% negative slip?