Calculating prop pitch

Ken O

Ken O

Member
Our new-to-us C-22 Cruiser with Honda 90 came with a 3-blade 13" aluminum prop. There's no markings on the prop as to pitch. It sounds like I would want a 15" pitch for this motor and this boat. Is there an accurate way to calculate the pitch? We haven't had the boat in the water yet, but I'd like to start off with the right prop. Would I just measure leading edge to trailing edge parallel to the shaft and multiply by 3?
 
Have you removed the prop from the motor sometimes there marked on the motor side of the hub. Boat weight and Altitude are going to have a big affect. You almost have to run the boat and see if you can get to WOT and work from there. Pitch is how far the boat moves with one revolution of the prop. Not counting any prop slip.


Measurements needed to determine the pitch of a propeller should be taken 3/4 of the way from the hub to the tip. To measure the pitch, lay the propeller flat on a table, measure 75% of the way from the hub to the tip, and draw a line across the propeller blade.
 
I just havcspentvtimecwith very sources getting two new props for Venture 23.
They are on order, need EC out before I try.
I boats has a good prop selection site.
Best if you can get a dealer to loan you a used prop to try.
 
jkidd":3dridkv8 said:
Have you removed the prop from the motor sometimes there marked on the motor side of the hub. Boat weight and Altitude are going to have a big affect. You almost have to run the boat and see if you can get to WOT and work from there. Pitch is how far the boat moves with one revolution of the prop. Not counting any prop slip.


Measurements needed to determine the pitch of a propeller should be taken 3/4 of the way from the hub to the tip. To measure the pitch, lay the propeller flat on a table, measure 75% of the way from the hub to the tip, and draw a line across the propeller blade.
Click to expand...

Ignore the measurement part of this it doesn't work took it off the internet.
 
Pitch is often obtained with computerized scans today. Pitch is not constant from hub to tip.take the boat out and see what the wot RPM ARE & SPEED. You should get 5500 to 6000 RPM. Speed should be near 30 mph, light boat.
 
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