Any propeller specialists over here?
In aviation there is a methodology for measuring the angle of a propeller blade, at a specific point on the blade, in order to calculate the propeller pitch.
Is there such a procedure for determining the pitch of a particular Evinrude/Johnson propeller? If so, what is the procedure?
Thanks.
The prop guys use measuring blocks for this as I recall.
Note, I am not being a wise guy here ... but on some OMC props I've had, the model#, if not pitch/diameter, were marked directly on the hub. It may be under the prop nut, or added washer is equipped ... so maybe you just can't see it ...Originally Posted by yam911
But as far angular measurement, you really need 2 points, as both a horizontal or vertical line, never mind one set on an angle, could theoretically all pass through the 'same reference point'.
"Life's too short for an ugly boat!"
1985 totally refurbished Pro-Line 21A Cuddy - 175hp Evinrude FFI
big number on prop followed by a P always works for me????
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ASE/GM Master tech before tools
I am looking for a lesson in calculating. Not a lesson in reading
I wanted to test a prop one time and the seller had no idea what pitch the prop was. I was also unsure if the hub would fit my motor so I took it buy my local prop repair shop and ask him to look at the prop. He used a prop pitch gauge to tell me what pitch it was. It only took him about 5 minutes to figure out the pitch. Do a google search for a boat propeller pitch gauge and you will see what I am talking about.
Try this.
The high-tech performance props often have a progressive pitch and a progressive rake to them meaning point on the blade face has a continuously different measurement, making it impossible to find a constant pitch size or other determination manually. They are labeled with a pitch-number from on-water testing to see how they compare in rpm to known pitched props.
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A Technical troubleshooter possessing more tools than talent !
++ to Seahorse - what he said. I guess the next question is what do you wish to learn? There is a much greater science in marine propellers, especially outboard propellers that only the engineers know.
Pitch is not constant on high speed marine propellers. The hydro dynamics of a marine propeller are different from the aero dynamics of aircraft propellers. I know only of a moving-needle gauge, similar to a protractor, used by propeller repair shops to measure pitch angles at multiple different points on the blade surface. Moving outward from the hub and either up or down on the blade face. Then pitch becomes some calculation of an ‘average’ pitch. A prop labeled as a 24 pitch can measure 22 pitch on the leading edge, 24 pitch in the middle and 25 pitch on the trailing edge. But none of this can take into account the parabolic shape of the blade.
I want to learn what the engineers know. Might not be able to understand it all however.
Talk to Mark Croxton he's a prop guy on the forums.
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