Problem with Inflatable dinghy with new motor

[dabull22]

I recently purchased a 1996 evinrude 8.0 for my 8'6" norlantic inflatable dinghy. The problem is that when I give it a lot of gas, an air pocket develops under the motor and it creates like a skipping motion with the boat. It is not that bad when I go slow but when I accelerate, the motor is not always in the water. The dinghy is rated up to a 9.9, so what do you think the problem is? I was thinking about cutting the transom down a few inches. Would that work???
Thanks!

Here is a pic

 

[Sea Rider]

Re: Problem with Inflatable dinghy with new motor

Seems you have a cavitation problem when at wot, what's your transom height: keel/bottom to where engine is mounted ? Must not exceed 40 Cm or will give this problem, need to cut down to max 40 Cm total height, just the portion where engine is mounted and re arrange engine inside/outside pad plates height as before. After that, place trim angle to match 2-3 hole out from transom and place all your weight towards bow. Will cruise much better. Do you have a slatted floor sib ?

Happy Boating

 

[deejaycee_2000]

Re: Problem with Inflatable dinghy with new motor

You can either move right to the back when going WOT or you can set your trim at one pin lower ..... no need to cut transom!

 

[Sea Rider]

Re: Problem with Inflatable dinghy with new motor

You can either move right to the back when going WOT or you can set your trim at one pin lower ..... no need to cut transom!

Probably will have a high bow rise performance placing all weight towards transom in such a small sib. Try different sib/engine configurations, that is, playing, moving weight aft or forward with different trim positions to see which suits you best. To cut transom down is last option if exceeding 40 cm total height, but that issue is not known

Happy Boating

 

[Howard Sterndrive]

Re: Problem with Inflatable dinghy with new motor

I'd try raising the motor an inch or two. not lowering it.

 

[Chris in Indiana]

Re: Problem with Inflatable dinghy with new motor

I've never heard of Norlantic boats, but it sure looks well made. Thanks for the pic. It's highly unlikely the boat was designed wrong and the transom needs to be cut down, something else is wrong. I have never seen an inflatable that requires a long shoft motor. Check the trim and make certain it's on the lowest setting, other than that play around with weight, which makes a big difference in such a short boat. By yourself, you might weigh enough to pull the motor out of the water if your sitting to one side, try putting your weight in the middle (forward) or having a passenger on the other side. On my 11ft I have to have my two boys (6 and 10) on one side while I'm on the other for smooth running. Too sharp of a turn will cavitate the prop.