My buddy has a 27 pro drive on a 16x52 all weld. With one person in it and no gear it will get the boat on top with out much trouble and turn 4200 rpm's with one man and a dog it will not get on top and the motor just sounds bogged down and will only turn 2900 rpm's. everyone said the boat was to heavy that aint the problem we cut everything out of it and removed all the foam we can pick the boat up and set it on the trailer weights 200 pounds at the most. with the motor in netural the prop is hard to turn to me so i think its something in the lower unit. any ideas??????

Prop being hard to turn in neutral is normal.

thanks for prop info

u say he has an All Weld, I'm thinking this is the brand, if that is the case, he would be better off with a boat that is made for a mud motor. Not saying that he can't use that boat, but it will perform better on a boat made for that motor....good luck

If u can turn 4200 by yourself and can only get 2900 when u add the dog, u must have a big azz dog.
U might have some valve issues. Is it an old engine? Have u tried trimming up so the prop will aerate and not bog down? Get a compression and leakdown test done.
The boat won't cause this much of a performance loss.

Any possibility you're getting air in your gas lines? Quick connects, tank properly vented, leaky fittings? Also, check to see if you're getting spark to both your cylinders?