Identifying Chris Craft Propeller

[Dale Genther]

I'm trying to find out what the pitch of an old Chris Craft propeller I have is. It is a right hand, three blade 1 1/4 inch shaft. It has Chris Craft stamped into it. The other stamping, that I believe identifies the pitch is 73? RH. Where I have the question mark is another figure, it may be a fraction or a percentage mark. Whatever it is, I can't read it.

[ssor]

Might 73(?)RH be 13C RH? Meaning, 13 inch pitch, cupped, Right Hand rotation?

[Dale Genther]

Nope, It is definitely a 7 not a 1.

As another option, does anyone know how I can measure the pitch of a prop?

[mmd]

Measuring prop pitch is not particularly easy, especially if you want good accuracy. Special tools and training are required. However, Dave Gerr describes a method to approximate pitch in his book, "Propeller Handbook".

"Pull the prop off the shaft and lay it face-up on a smooth, flat surface. Holding a 45-degree right triangle at right angles to to the prop's radius line, slide it along the length of the blade - between the blade back and the flat surface - until it just fits beneath the contour of the blade. Measure the distance from the prop centreline, and you will have found the radius at which the prop pitch is 45 degrees. The true pitch is two times this radius times pi (3.1416). You will have to make some allowance, by eye, for any convexity of the blade back."

Example: If the triangle fits flush under the blade back at 6.5" from prop centreline,

P = 2 x 6.5 x 3.1416
P = 40.8"

[Gary E]

Dale,
Your not far away from these fellows...

Black Dog Propellers
212 Log Canoe Circle
Stevensville, MD, 21666
Contact: Steve King
Toll Free: 888 558 0921
Ph: 410 604 2861
Fax: 410 604 2863
Web: www.blackdogprops.com (http://www.blackdogprops.com)

Read up on them here...
http://www.props.com.au/inspection_system/features.htm

[pcford]

Props are usually stamped with diameter first then pitch. For example, 13x13.

However, the older Chris propellers were different. The number has no direct correlation to size. It is simply a part number. A prop shop that has been around a while may be able to help you decode the number.