Measuring pitch (Backyard)

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Blacksting

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Is there any (backyard) way to measure the pitch of a prop. ? I have 3 spares and the stamps are too faded to read . I was thinking of laying 3 sticks against the sides and using a speed square to get the angle . Is there a better method out there ?
 
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Silvertip

Silvertip

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Re: Measuring pitch (Backyard)

Pitch is not measured in degrees -- they are measured in diameter and INCHES of pitch which requires a "pitch block" for accurate pitch determination. Therefore a prop with 19 inches of pitch theoretically moves the boat forward 19 inches with each revolution of the prop. Since a prop operates in a liquid, slip enters the picture and a prop with 10 - 12% slip would be fairly efficient. Someone once posted a way to measure pitch so use the SEARCH feature to try and locate it or else google the method. Don't know how accurate the technique is.
 
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steelespike

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Re: Measuring pitch (Backyard)

have you looked under where the prop nut goes and sometimes under the back side of the hub.
 
tpenfield

tpenfield

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Re: Measuring pitch (Backyard)

No real backyard way of telling the pitch of a prop that I am aware of. As Silvetip explained it is a theoretical amount of movement per revolution, subject to the imperfections of traveling in a liquid. Probably something that the designers of props use a computer to figure out.

If you can grab any kind of number(s) off the propeller and/or hub, then you might be able to Google your way to an answer.
 
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fishndirk

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Re: Measuring pitch (Backyard)

You would have to have some preaty complicated angle measuring equipment and be VERY good at math conversions. The number of inches that a prop pitch number represents is the average inches of travel that exists in the blade angle. A 14" pitch prop may be 19 inches at the base of the blades and 10 inches at the tips. The 14 for example is the average between the base and the tips.
 
Texasmark

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Re: Measuring pitch (Backyard)

fishndirk said:
You would have to have some preaty complicated angle measuring equipment and be VERY good at math conversions. The number of inches that a prop pitch number represents is the average inches of travel that exists in the blade angle. A 14" pitch prop may be 19 inches at the base of the blades and 10 inches at the tips. The 14 for example is the average between the base and the tips.
Click to expand...

Yeah verily, as a lot of props actually are in several dimensions of pitch as you traverse the blade from front to tip, inside to outside.

Mark
 
B

Blacksting

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Re: Measuring pitch (Backyard)

Silvertip said:
Pitch is not measured in degrees -- they are measured in diameter and INCHES of pitch which requires a "pitch block" for accurate pitch determination. Therefore a prop with 19 inches of pitch theoretically moves the boat forward 19 inches with each revolution of the prop. Since a prop operates in a liquid, slip enters the picture and a prop with 10 - 12% slip would be fairly efficient. Someone once posted a way to measure pitch so use the SEARCH feature to try and locate it or else google the method. Don't know how accurate the technique is.
Click to expand...

Well, after being blinded by science and a lot of excellent answeres , i get the picture . which brings me to , use a tach. and the old trial and error method . thanks guys , i'll keep my speed square where it belongs , in the tool pouch. btw Texasmark learned me a new word , traverse, i mustve needed it a thousand times to try and explain a complicated situation .
 
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Blacksting

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Re: Measuring pitch (Backyard)

r.j.dawg said:
Ask and ye shall receive.

Click to expand...

good vid. but i dont think theres' too much room for margin of error . in my case i have 3 props to compare each other to , so it should make it that much easier . the hardest part might be finding the printouts . chaulk one up for j.dawg and the boys from down under .
 
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talon8

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Aug 23, 2011
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Re: Measuring pitch (Backyard)

You can take them to a prop shop and they'll see which pitch block best fits, thus giving you the pitch. Not exactly back yard but at least on land.
 
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