water comming over the transom

[ronnieray]

Hi boaters!
I recently purchased an aluminum fish / ski boat. Its a 17 ft, 85" beam, walk through window, deep V type boat. It's paired with a 90 HP Merc ELPTO power trim engine.

When we get it up on plane, water comes back in over the transom. If i trim it ip high enough to stop the water from comming back in over the transom, then it begins to porpoise too much. I have an auto /float type bilge and I have to keep it always on in rough water cause the purpoising really gets out of control when the water is rough and I have to trim it down a bit, then the water comes in.

Why can't I trim it to prevent porpoising without taking water over the back?

Would getting the engine raised or lowered help?

There is a boarding ladder that just barely scratches the water when up on plane. Could this be contributing to the problem?

What if anything could I do to improve this situation or to seek help with it?

 

[tashasdaddy]

Re: water comming over the transom

that ladder is causing part of the problem, the other may the how the engine is mounted. if you continue a straight line out the back of the boat at the keel the AVplate (flat plate above the prop) should be 1 in above the line, and horizonal with the line. porpoising you may need to add some weight to the bow, if you can't work it out with the trim.

 

[BF]

Re: water comming over the transom

by water coming in, I guess you mean that there is some splash back (?).. ditto that the ladder might be part of it... If your outboard puts up 2 splashes to the sides that go more or less straight up, that's usually an engine mounted too low I think. Do as td suggests and check out where the anti-ventilation plate is in relation to the hull... I'd guess you've got to go up a hole or two. Hopefully it's not a long shaft motor on a short (16") transom.

 

[ronnieray]

Re: water comming over the transom

Thanks,
I removed the boarding ladder today and added 30 lb weight to the frontmost compartment. I will go try it out in a few days and see if I can get a better trim position.

 

[tashasdaddy]

Re: water comming over the transom

did you check the alignment of the AV plate to the bottom?

 

[kenmyfam]

Re: water comming over the transom

Interesting one, looking forward to a reply with some feedback.