Prop has no markings...what do I have/need

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bduffel

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I have an 87 Polar Kraft 16' with a 91' Merc 4 cylinder 40 HP ELPTO tiller motor. Boat and motor are great. Seems to struggle a bit on accelerating to plane but not bad and top speed seems OK.

Question is what is the original prop? The only markings on the aluminum prop are "20 / OR 11". The 11 could almost be "//" instead of two ones. It is a three-bladed prop.

The prop diameter is about 10 1/2" or 11" and it is aluminum.

Is there any way to measure and cipher out the pitch?

Just curious in case I want to increase the hole-shot and/or top speed; or just obtain a spare/new prop.

Thanks,

BDUFFEL
 
You might try going here and enter you motor info. Then get the prop info from the parts diagram.
https://www.crowleymarine.com/parts.cfm
 
Thanks for the suggestion but that didn't reveal any info. Thanks again.
 
To the best of my memory, there was no "standard" size prop. The motor was ordered propless and then the dealer was to guess at which prop would be best for it. The only true way of knowing which direction you need to go with prop sizing is to look at a tachometer and go from there. Otherwise it's just a guess.
 

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