Pitch

[All U Get]

Hi all,

I have a Max prop, thanks to the PO, and was wondering if I could measure the pitch of the blades? It seems easy by reading the literature, but I don’t want to take it apart.

 

[dlochner]

Probably. Recently I rep itched my Max prop, it is easier than the instructions lead one to believe. There is some juggling involved and the parts get slippery with grease, but not terribly difficult.

If you go this route, buy the 1/16" cotter pins from McMaster-Carr. For the same cost from PYI, McMaster will sell you a lifetime supply.

 

[sail sfbay]

Get a tape measure, grease pencil, protractor and calculator with TAN or tangent function. Use the grease pencil to draw a line around the propeller hub. Set the base of the protractor against the blade of the propeller and note the angle on the protractor between the blade of the propeller and the line drawn around the hub. Use your calculator's "TAN" to determine the tangent of this angle. Multiply the tangent of the angle by 6.2831. Multiply the result by the radius of the propeller. The result is an approximation of the pitch. Pitch is always a whole number; if you get a fractional answer, round the number off. For example, if the diameter of the propeller is 14 inches, the radius of the propeller is 7 inches. The angle of the blade is 20 degrees. The tangent of 20 is 0.36397. 0.36397 x 6.2831 x 7 = 16.0080. Rounded off to the nearest whole number, this means that the pitch of the propeller--the second element of this propeller's measurement--is "16." How to Measure a Boat Propeller (goneoutdoors.com)

 

[All U Get]

Get a tape measure, grease pencil, protractor and calculator with TAN or tangent function. Use the grease pencil to draw a line around the propeller hub. Set the base of the protractor against the blade of the propeller and note the angle on the protractor between the blade of the propeller and the line drawn around the hub. Use your calculator's "TAN" to determine the tangent of this angle. Multiply the tangent of the angle by 6.2831. Multiply the result by the radius of the propeller. The result is an approximation of the pitch. Pitch is always a whole number; if you get a fractional answer, round the number off. For example, if the diameter of the propeller is 14 inches, the radius of the propeller is 7 inches. The angle of the blade is 20 degrees. The tangent of 20 is 0.36397. 0.36397 x 6.2831 x 7 = 16.0080. Rounded off to the nearest whole number, this means that the pitch of the propeller--the second element of this propeller's measurement--is "16." How to Calculate Marine Gear Ratios (goneoutdoors.com)

Oh. I checked the article and read the same formula. Too bad the pictures were from a bad liver ad.

I watched the u-tube video of a disassembly which seems easier to figure the pitch, but requires time on the hard. Dave you’re right about the cotter pins.

 

[sail sfbay]

Try this link: How to Measure a Boat Propeller (goneoutdoors.com)