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Old 04-22-2018, 11:16 PM
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Flex Flex is offline
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Join Date: Feb 2016
Location: Elk, Texas
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Default Need help with porpoising

Hey guys, need some help. My boat is a 17' mod v aluminum. I'm running a 70 Evinrude with a 6" jack plate no tilt/trim.

I have been through multiple props and here's my issue. If i trim it down it doesn't porpoise at all, but i lose speed. If i trim up i gain speed but porpoise, and it gets worse as i accelerate. If i trim motor down one notch i lose speed and bow is too low but no bounce.

I've tried about 4 different props, just had a racing prop guy add some cup, adjust rake and shave tips on my 13 3/8 17 pitch stainless.

I swear it gave me even more stern lift!

I do have gas tank up front under decks but even when I'm only on a few gallons it handles the same.

I came across some old posts about adding hook in the rear. Does this sound like it may help?

I run 40 at about 57-5800rpms porpoising. I think I'll lose water pressure if i crank jack plate any more.

I can attach pics if anybody needs to see what I'm working with.

Sorry for the essay guys. Beating my head against the wall two years on this thing!

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