You are turning 78 RPM, with a propeller...

You are turning 78 RPM, with a propeller...

Question 1 of 27070

Q

You are turning 78 RPM, with a propeller pitch of 21 feet, and an estimated slip of -7%. What is the speed of advance?

A

15.7 knots

B

17.3 knots

C

14.9 knots

D

17.8 knots

Question 1 / 2707066636eea28f7522a1c51b6f5

Question 1 of 2707066636eea28f7522a1c51b6f5

You are turning 78 RPM, with a propeller pitch of 21 feet, and an estimated slip of -7%. What is the speed of advance?

Question 1 of 27070

Study area:

Study area:

Q

You are turning 78 RPM, with a propeller pitch of 21 feet, and an estimated slip of -7%. What is the speed of advance?

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🔍 Key Concepts

• Propeller pitch as theoretical distance traveled per revolution • How RPM and pitch combine to give a speed in feet per minute • Effect of negative slip (-7%) on theoretical speed and converting ft/min to knots

💭 Think About

• First, ignore slip: with 78 RPM and 21 ft pitch, how many feet per minute would the propeller advance in theory? • Next, apply the -7% slip: does this make the actual speed greater or less than the theoretical speed? By what factor? • Finally, convert your corrected feet per minute to knots (remember: 1 nautical mile = 6080 ft and 1 hour = 60 minutes). Which choice is closest?

✅ Before You Answer

• Confirm you correctly compute theoretical advance per minute in feet using RPM × pitch • Be very clear on the meaning of negative slip (is the actual advance more or less than the theoretical?) • Check your unit conversions: ft/min → nautical miles per hour → knots, then compare to the answer choices