Question 65Navigation Problems70% to pass
If the speed necessary for reaching port at a designated time is 23.7 knots and the pitch of the propeller is 20.8 feet, how many revolutions per minute will the shaft have to turn, assuming a 7% negative slip?
AI Explanation
The correct answer is B) 108 revolutions per minute.
To calculate the required shaft revolutions per minute, we can use the formula:
Shaft RPM = Speed / (Pitch * (1 - Slip))
Given information:
- Speed = 23.7 knots
- Pitch = 20.8 feet
- Slip = 7%
Plugging in the values:
Shaft RPM = 23.7 / (20.8 * (1 - 0.07))
Shaft RPM = 23.7 / (20.8 * 0.93)
Shaft RPM = 108
The other options are incorrect because they do not correctly apply the formula and account for the 7% negative slip.
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