Re: Can't plane
 

For what it's worth, I went through this same thing -- prop was appropriate (14.5 x 19p), but there just wasn't much oomph. Turned out to be a bad carburetor that was very corroded, along with a lot of water in the gas probably as a result of ethanol.

With a rebuilt carb, fresh gas, and a pledge to use StaBil Marine Formula, it (finally) screams out of the hole.

Re: Can't plane
 

Thanks to all for the suggestions. I just had a new Mercury prop installed with 19" pitch and it solved the problem, planes easy and quickly and I gained 13 more in speed.:)