Outboard putting up water roost at low speed

[Jerrers]

I need some help to find a solution to a problem I'm having. I have a Signature 540F and recently repowered with a Suzuki DF140A. I absolutely love the motor, more power than the old Johnson 115 and less than half the fuel. The problem is the motor pushes water up in the air directly behind the cowl. My main concern is water is going into the rear air inlet on the cowl and over the block, I need to remove the cowl after every use and wash the salt of the block.

It usually happens around 2600-3000rpm just before the boat gets on the plane. Triming the motor in or out doesn't stop it (although it alters the rpm which it happens at). I initially had the motor height set at the 4th hole from the top and have since lowered it 1 hole, it improved slightly, but not a lot. I don't want to lower the motor any more.

Currently I am running the standard Suzuki aluminum 14x19 prop and have a permatrim installed. I was considering changing the prop to SS 3 or 4 blade.

Has anyone experienced this before and have any suggestions to stop or reduce height of the water. Cheers.

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[aussiebasser]

Try it without the Permatrim

[Skusto]

Check the other threads about setting up engine height it may be way to low!

Other problem why this can happen is it is bum heavy and doesn't like the 4 stroke weight.


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[hainsofast]

Chuck 80kg of weight up the front see how it goes, but like old mate said, motor may be too low, how far under the water is the permatrim when you are on the plane?

[Jerrers]

There's only 20kg difference between the old 2 stroke and the 4 stroke and I already have 40kg ballast up the front to counteract the 540f's natural lean to the right.

I originally had the motor in the 2nd highest hole and have since dropped the motor down 1 hole. Overall it ran better higher up but since dropping the motor down it has reduced the height of the water a little. I guess by dropping it is pushing water further below the water line.

Taking the permatrim off makes no difference.

[Bremic]

Can you get a photo from the side, showing bottom of boat and cavitation plate?

[Jerrers]

I'll takeva photo in the morning, from memory the cav plate is about 2in higher than the bottom of the boat.

I didn't have this problem with the old motor although i was runnings a solas ss 4 blade and the motor was lower than where it is now.

[Skusto]

What is the weight different but? If you have added 50kgs of weight that can change the whole dynamics of the boat!


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[Jerrers]

The 40kg of ballast is under the port bunk and has been there for the last 5 years. There is a lot of glass and timber in the helm, with nothing on the port side.

I think the motor should be higher but as i said the symptoms were worse when i had the motor up a hole higher.

Attachment 115167

Does anyone have any thoughts about prop choice? Would a 4 blade prop bite and hold more water and slowing the water being pushed back?

[gofishin]

Something very strange going on. As a guess i would say motor too low and donk trimmed too far in... but we all know guesses are fraught with danger, and 2" above sounds like a good start.

The rooster looks like it is more on the port side of the motor. Is this true, or just an optical illusion? If true, where is the steering trim tab set? (if the zukes have one?) Looking from the back/behind the motor, is it kicked over to port?

There are a few owners (& past owners) of 540's & later model variants on here, maybe they will comment from their experiences with this hull/combo. (GBC has/had one if i recall).

Cheers
Brendon

PS. last pic did not work

[Skusto]

4 blades will help with stern lift, probably either give propeller warehouse a call or Solas.

Failing the 4 blade helping your only other option would be trim tabs and using them when coming off the plane for stern lift.

Or probably a big pod for extra bouancy


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[robothefisho]

I haven't ever seen motors roosting water because they are too high. Plenty do when to low.