Permatrims

Thinking of putting a permatrim on my outboard. It's a 25hp Mariner and pushes a 3.8m Zodiac inflatable. Outboard goes really well on this size boat, problem being that it's very happy in the front and keeping it down with only a couple of people and gear on board is a bit of an art , when on the plane it's fine and nice and stable and goes like a rocketship it's just that coming on and off the plane it likes to put the front up. Am I right in thinking that a permatrim would go a long way towards correcting this behaviour and possibly even allow planing at a much lower speed?

Yes.

Yes it will. You may find once fitted that you need to ring the leg a notch lower.

I've had one on a couple of boats I've owned, although not rubber boats but yes it let's you plane at lower speeds and can help you keep the nose down.

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Originally Posted by Woody

Yes it will. You may find once fitted that you need to ring the leg a notch lower.

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I have found the opposite, with the plate above the prop preventing ventilation I went up a hole improving speed and economy.

My mate had one put on his Fyran. It went from an appalling ride to just a bad ride, so yes, I think it will do what you want.

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Originally Posted by veitnamcam

I have found the opposite, with the plate above the prop preventing ventilation I went up a hole improving speed and economy.

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Same deal here. Raised the engine until there was barely a few mm running across the top of the permatrim when planing.
No issues with cavitation. Same configuration for the last 10 years, and still happy with it.

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Originally Posted by Woody

Yes it will. You may find once fitted that you need to ring the leg a notch lower.

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I am referring to trim angle, not depth of cavitation plate.

Then you find another school of thought. Some will say that these devices cover up inherent flaws in the boat design or use.

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Originally Posted by outlander

Then you find another school of thought. Some will say that these devices cover up inherent flaws in the boat design or use.

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That's my understanding too, but if you've fiddled with everything else and can't get it right, then go for a permatrim.

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Originally Posted by outlander

Then you find another school of thought. Some will say that these devices cover up inherent flaws in the boat design or use.

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People who say that usually give advice like get a bigger boat.
I think virtually all small boats would benifit from having one fitted.

Yes a permatrim will help keep the nose down
but on lightly loaded small boats eg driver only they can lift too much of the boat out of the water making them a bit squirrelly

your other option is going for a prop with more lift ie a 4 blade but propping isnt an exact science either
what prop is it running at the moment?


permatrims can also apply excessive pressure to the leg of the outboard think big lever with most of the weight of the boat on it


have just re propped and removed se300 hydrofoil on current 4.5m boat and have gained 6kph and planing ability hasnt changed

Works well on my 18hp tohatsu pushing 12ft parkercraft

I have an alloy one on a 30 on a 4m alloy pontoon boat. I had heard that in a following sea on a surf break they can shunt you around a bit in a small boat but I have not experienced this myself. The sturdy alloy ones like mine are are handy for getting in and out of the boat as you can stand on them if you are not too hefty. I think they are also supposed shave a bit of top speed off?