If the speed necessary for reaching port at...

Question 1 of 2707066636eea28f7522a1c51b5b5

If the speed necessary for reaching port at a designated time is 17.8 knots and the pitch of the propeller is 24.7 feet, how many revolutions per minute will the shaft have to turn, assuming a 7% positive slip?

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Question 1 of 27070

🔍 Key Concepts

• Speed–pitch–RPM relationship: how propeller pitch (in feet per revolution) and vessel speed (in knots) relate to shaft RPM with no slip • Slip: the difference between the theoretical distance advanced per revolution and the actual distance; understand what positive slip means • Unit conversions: especially converting knots to feet per minute before using pitch (ft/rev)

💭 Think About

• First, find how many feet per minute the vessel must travel to make 17.8 knots, then think about how pitch in ft/rev links distance traveled to revolutions per minute with no slip • Ask yourself: with 0% slip, what RPM would be required? Then, how does a 7% positive slip change that RPM requirement? • Compare your computed RPM to the answer choices and see which is closest after accounting for slip

✅ Before You Answer

• Be sure to use 1 knot = 6080 feet per hour (if that is the convention used in your exam materials) and then convert hours to minutes correctly • Confirm that you are increasing RPM when accounting for positive slip (actual advance is less than theoretical) • Double-check that your final RPM is in the same range as the answer choices (roughly tens of RPM, not hundreds) before choosing