# Thread: How to measure prop pitch

1. ## How to measure prop pitch

So I decided to do some measuring on my 17/22 just for reference. Do you measure the angle of the forward side or the backside? Due to the thickness of the blade, it changes the angle by 5+ deg depending on which side you measure.

I guessed that I should measure on the back side (this would be the "pressure" side) and got that my prop is actally a 17.5/20.

Mike

2. Originally Posted by engineermike
So I decided to do some measuring on my 17/22 just for reference. Do you measure the angle of the forward side or the backside? Due to the thickness of the blade, it changes the angle by 5+ deg depending on which side you measure.

I guessed that I should measure on the back side (this would be the "pressure" side) and got that my prop is actally a 17.5/20.

Mike
Measure the side that pushes the water.

3. Whats the first number? and the second?

4. Originally Posted by Pilot_85
Whats the first number? and the second?
the first number is the leading edge
the second number is the trailing edge

Here is a pic of a leading edge being measured

5. Originally Posted by RX951
the first number is the leading edge
the second number is the trailing edge

Here is a pic of a leading edge being measured

Where did you get this?

6. Originally Posted by cbrich
Where did you get this?
that is a template I got from Fernando that he had printed on some clear transparency.

2fast4u sells them also printed on clear lexan cylinders

Here is the template if you wish to print your own on clear transparency

http://greenhulk.net/forums/showthre...impeller+pitch

,
,

7. Do we mess with the leading or trailing edge when fine tuning the impeller.

8. Ok, so WFO says to measure the side that pushes water, which I did, but the pic posted by RX951 shows that he's measuring the opposite side (that doesn't push water).

Mike

9. Originally Posted by engineermike
Ok, so WFO says to measure the side that pushes water, which I did, but the pic posted by RX951 shows that he's measuring the opposite side (that doesn't push water).

Mike
From his pic you measure the bottom edge of the blade.