engine change now boat wont plane

[englishjeff]

Hi can anyone please help me with some advice my problem is that I change my short shaft outboard 50hp mercury to a long shaft as the short shaft blew a piston it was a big job as I ended up replacing the whole transom (which was rotten) it order to get the fin bit of the gearbox to line up with the bottom of the transom but now the boat is a lot slower and does not plane. Any suggestions would be very very appreciated. Many thanks in advance

 

[midcarolina]

Is the prop the same prop or same pitch as the short shaft prop? can you attach a pic of the setup makes it much easier to trouble shoot the issue.

 

[Mel Taylor]

Is the prop the same prop or same pitch as the short shaft prop? can you attach a pic of the setup makes it much easier to trouble shoot the issue.

Could very well be a prop pitch problem and, midcarolina is right, pictures would make it a lot easier for us to help you.

 

[JimS123]

The transom is the wrong height, or the prop is the wrong pitch, or the prop is spun, or the motor is only running on 1 cylinder.

Measure the height of the transom at the keel and provide speed and rpm readings.

 

[NYBo]

What the others said.
1. Verify that the motor height is correct. The anti-ventilation plate should be even with or a little above the keel.
2. Verify that the motor is reaching the proper RPM range at wide open throttle. If not, you could be over-prop (pith too high) or the motor is weak for some reason.
3. Verify that the trim setting is proper. If the motor has power T&T, start with the motor trimmed all the down (toward the transom). If it doesn't have power T&T, move the pin one hole at a time to move the motor toward the transom until you can get on plane.

 

[englishjeff]

No Title

Thank you all very much for your replies. I have done some inspecting as wonted to rule out water saturation of the wood so I look under the whole of the floor at the deck with a video camera and all is bone dry. Big relief. .. I did find a bit of water at the back in the foam which I have removed now. I'm going to change the prop from the short shaft thanks again. I did have fins (I have removed them now)on the outboard which never lifted out the water like I hoped the fins line up just above the bottom of the transom so I think the outboard hight is set right it's just not getting up on the plane. Thanks to all that have replied I will update after the weekend when I take it out again.