25 hp Johnson spun prop?

[Volksdragn]

I have a 25 hp Johnson short shaft on a locally manufactured 14ft skiff. The boat runs great, plains off,spits water the whole nine yards. After running for a while the engine seams to over rev, lose speed and the water pump quits spitting. When I back off the throttle and get back into it, it gets back on a plain and runs fine. What could cause it to over rev like that an stop spitting at the same time?

 

[Bosunsmate]

Re: 25 hp Johnson spun prop?

cavitation into the pick up/prop.
How high is your motor on the boat?

 

[lindy46]

Re: 25 hp Johnson spun prop?

Normally, once a prop hub is spun, that's it for high speed. It may move the boat at very slow speeds, but once you advance to high speed, you will go nowhere.