Prop sizing - what does it represent

[landonshaw]

I have a MD2040D Volvo engine. I might have to replace the prop. I am seeing numbers in the schematic like - 14 x 10 x 25.

I believe that:
The 14 is a measurement from the tip of the fin to the tip of the other fin. Two fins on my prop.
The 10 is the pitch
What is the 25?

Am I correct on the definition of the other two numbers?

Thanks
Aloisius

[kenbo]

25 mm is your shaft diameter and yes the the other numbers are correct

[kenbo]

That's also a left hand prop. It would also be good to know if the taper on the shaft is 10 to1 (most likely) or 16 to 1.

[landonshaw]

If you do not know the pitch on a prop, the marking is not clear, is there a way to measure the pitch on an existing prop?

[kenbo]

Yes bring it to a prop shop

[kenbo]

if you have a protractor you measure the angle the blade makes from perpendicular at 75% of the radius. So if your prop is 14", then .75*7=5.25" from the center of the prop hub. There are tables to convert degrees of pitch to inches of pitch.

[kenbo]

But I wouldn't buy a prop based on schematics unless your absolutely sure that the prop was an unmodified original and you verified that the prop could allow the engine to get to 90-95% of rated RPM.

[landonshaw]

I will pull the prop this weekend and see if I can read the markings. Thanks!

[j.g.evans]

You can go to 5 prop shops and get 5 very different answers as I did years ago. There are 2 sources that I have faith in: 1) Propeller Handbook by Dave Gerr and 2)http://www.vicprop.com/displacement_...tion=calculate
The vicprop online calculator will be the fastest way.

[Geoff 3016]

If the pitch has been altered by a shop , the new pitch is usually stamped on the end of the hub at the small end of taper.

[iris]

When I had to replace our propeller, I looked into the engine specification related to the size and yacht brand.
Good lack