You are turning 68 RPM, with a propeller...

Question 1 / 2707066636eea28f7522a1c51b6f1

Question 1 of 2707066636eea28f7522a1c51b6f1

You are turning 68 RPM, with a propeller pitch of 18 feet, and an estimated slip of +2%. What is the speed of advance?

Question 1 of 27070

You are turning 68 RPM, with a propeller pitch of 18 feet, and an estimated slip of +2%. What is the speed of advance?

🔍 Key Concepts

• Speed of advance (SOA) vs. speed through the water • Propeller pitch formula: theoretical speed from RPM × pitch • How to apply percentage slip (+ or -) to the theoretical speed

💭 Think About

• First, ignore slip and find how many feet the ship would move ahead in one minute at 68 RPM with 18 ft pitch. What is that distance per minute? • Convert that distance per minute into knots. Remember: 1 nautical mile = 6076 feet and 1 knot = 1 nautical mile per hour. • Once you have the theoretical speed in knots, adjust it for +2% slip. Does +2% slip make the actual speed slightly higher or slightly lower than theoretical?

✅ Before You Answer

• Be sure to convert minutes to hours when going from distance per minute to knots. • Confirm whether a +2% slip means you multiply by (1 − 0.02) or (1 + 0.02). Think about what slip physically represents. • After adjusting for slip, check that your final speed is reasonable and close to one of the choices (not something like 5 knots or 20 knots).

Question 1 of 27070

You are turning 68 RPM, with a propeller pitch of 18 feet, and an estimated slip of +2%. What is the speed of advance?

11.5 knots

12.3 knots

10.7 knots

11.8 knots