Tunnel problem

[rktman]

Hey guys, I've got a 1542 flat bottom alweld with a tunnel. I can't seem to get my motor height correct. I have it set fairly high, front grate pin is even with a straightedge on the tunnel. I have a 4-5" splash plate in front of the foot.
Using 2ND pin out which seems to have the best speed.

My problem is excessive splash which is so bad going up that it splashes water into my motor electrical components and shorts it out. Also, any chop at all creates cavitation.

Any suggestions(beyond closing the tunnel)?
Thanks

 

[rktman]

I took it out today, dropped it about 1/4" and the spray is all but gone, just sensitive I guess..

 

[JL8Jeff]

The tunnel seems to make is really sensitive to slight changes. If I trim the motor up just a little bit, i get srpay back coming over the transom. But if I mount the motor the next hole up, I get a ton of spray so I'm at the best height without a jack plate. I don't need to go fast with this boat so I haven't really messed around with it much.

 

[redrum]

Outboard jets own website suggests against using a tunnel on a flat bottom boat. I would suggest a splash / spray plat if you don't have one to take care of any spray problems.

 

[rktman]

Update for future tunnel readers,

I have adjusted the jet height and tilt to the optimum setting (lowest spray, cavitation, drag).
My friends suggested moving the motor to the right a little. This has helped a lot with the cavitation issues.
The reasoning is that the intake is pulling from the left and the tunnel has a focused flow area, so the cleaner water is more inline with the motor being slightly offset to the right.
I gained some speed and the spray pattern looks better.