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Johnson 70hp 1975 outboard prop

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boatiebur

New member
What would be the best prop for my boat. I have a 15 ft runabout that I like to use for cruising. What was the standard size prop Johnson would use for these older outboards. I am relatively new to boating and I'm curious to read your feedback.
 
There was no "Standard" prop. but the motor was shipped from the factory with a 17" aluminum 3-blade. It was the dealer's responsibility to swap it for the best prop for the boat the motor was to be used on, and he could return the 17" for credit if necessary. Having said all that, we found that the 17" was good for the average boat/load, which your boat would fit into the "average" catagory.

Consider springing for the extra bucks for a stainless steel prop if you will be boating in skinny water where you will be touching bottom. It will pay for itself in the long run because it is so much stronger than the aluminum prop which will quickly self destruct.

Best bottom line advice: If at all possible, buy from a dealer that will allow "try before you buy".
 
Good advice from Racer, FDR, and Boobie. 13 1/4 X 17 is a pretty common prop on those engines. I had a 1978 70HP on a 15' tri-hull several years ago. That hull had a good bit of drag so the 17 pitch was a little too tall when I had 4 adults in the boat. I changed to a 13 3/4 X 15 and that allowed to run up near 5,500 RPM and give me the max power I could get out the engine.

KJ
 
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