17' 1969 Powercat porpoising

[kpbulldog1996]

I've got a 17' 1969 Powercat that I'm refurbishing. I've put a 1979 Mercury 140hp engine on it with what I believe is a 19 degree Johnson prop with Mercury hub. The problem I have is that the boat porpoises at virtually any speed and trim combination. Any suggestions as to what the problem is?

 

[Cadwelder]

Re: 17' 1969 Powercat

Re: 17' 1969 Powercat

Welcome to the iboat Dry Dock.


I don't think this is the proper place to get your question answered. You'd be better off to post it under props.

 

[steelespike]

Re: 17' 1969 Powercat

Re: 17' 1969 Powercat

Did you work on the stringers and floor?Replace the transom? Is the boat rated for 140?Is the motor mounted as high as possible on the transom?