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Discussion Starter #1
So I trying to see if I screwed up. I have an older 80s model 35 Evinrude and a 4" setback JP it's as low as it will go. The cav plate or AV plate depends on who you talk to is about 3" from the bottom of the keel. Do I need to remove the JP fill the holes drill new holes and remount it lower

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Discussion Starter #4
I don't know I just put the motor on. Its my skiff project. I just finished I attached the jack plate and I think I may have mounted it a little high. If it was a modern outboard I think I would be ok, but its an older Evinrude and I am concerned about it picking up water.
 

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Hey! From what I know, your skiff is going to drift and slide a lot if the motor is mounted like that. You also have a jack plate, so if you put your jack plate up it looks like your entire motor will be out of the water on plane. I would definitely lower it and where you have the motor now is around where it should be with your jack plate close to all the way up, in my opinion.
 

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Lower it.... first... That motor plate should be about one inch above the keel on your hull at your average running position - before trying to jack it up at all. Whatever you do make sure you have a water pressure gauge before doing any testing... so that you can see immediately if, when up on plane your motor isn't getting water. It would be a great idea to find that out before cooking the motor if you're set too high... Looking at your photo shows me you're not measuring it from the keel as well. Have someone run a straight edge right on the keel - then measure from the top of the plate down to the top of the straight edge to see just how much too high you are...

Were there bolt holes in your transom before you set that jacker in place? If there were, in all probability they were set correctly at the factory on factory built boats... Sure would be nice to drill any NEW holes in the jack plate instead of the transom - but not a problem if you do have to re-drill your transom....

"Aren't boats fun?"
 

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Discussion Starter #8
The original transom was designed for 15'' shaft outboards it had a cutout motorwell. I raised it even with the sides straight across when the transom was replaced. so any bolt holes would be no good now besides they were filled and covered during the rebuild. I already decided to pull the JP off and fill my holes. I waiting for the epoxy to cure and I will mount the jack plate about three inches lower maybe more.
 

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Discussion Starter #10
Cav plate
That's what I thought it was called, but I was reading online and they keep calling it AV Plate. So I wasn't sure.
 

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It likely won’t get on plane without blowing out. I could be wrong though, especially if the boat sits low enough in the water. I mounted my motor at about the same height, didn’t expect it to plane without the compression plate on, and found it wouldn’t. With the plate on it runs and handles great, excellent water pressure, no cavitation when turning or in a chop. Running a Powertech SRA3
 

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I would have ran it first! The water pick up is below the cav plate in the pic so that wouldn’t have been a problem. Maybe cavitation but a good prop would have fixed that!
 
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Discussion Starter #14 (Edited)
So I finally got it running and got to take it out. While the motor itself seemed to run fine it wouldn't get the boat up on plane. The motor was not all the way down and we ended up getting it all the way down because any higher was causing a blow out. So I would have thought that the little 35 would have been enough to get the boat on plane. Its possible I am running the wrong prop. I am almost certain I am running a 13 pitch prop. I may need to run 9 or 10 pitch prop. Any suggestion beyond getting a bigger motor?
 

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Discussion Starter #16
My concern is the cost vs benefit. The motor itself is maybe worth $700 possibly a little more. Its a 1981 35 evinrude. Its not new. That's 35Hp at the crank not the prop. They didn't change that over until around 1983. So I am not sure how that would compare to other "newer" outboards. The boat is rated for a 50hp and its a 1986. Its also a little heavier than when it was originally built. I can't think added more than 100lbs considering what I took out and the materials I replaced it with. My reading has said that you really need to be at at least 75% of max horse power. I am short even if you take the Hp rating at face value. So purchasing a $200+ dollar stainless custom prop seems like a waist of money on something that may never get the performance or end result I need, but lowering pitch and buying an $80 dollar aluminum prop that may get the boat on plane is worth a shot. Hopefully I can get to point that I will be satisfied until I can save up the pennies to buy a newer outboard in the 40-50hp range and sell my good running but not adequate outboard. I purchased the jack plate in hopes that I would eventually be able to upgrade and that it would improve the performance of I what I have.
 

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Did you check the compression on motor? I would have thought that 35 was enough for plane but I'm sure it would perform better with a max hp motor on it.
 

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Discussion Starter #19
I would have too. I am not sure what the deal is. Based on my very rough estimate I would need at least 30hp to bring the boat on plane. The motor is 35hp, but that's at the crank not at the prop. So maybe its 25 at the prop. The boat before I repaired it and added the deck had a dry hull weight of around 475lbs I added around another 175 or maybe 200 so in material and that doesn't account for anything removed. That was a lot. It includes transom floor and the short front deck. It was all ply wood and I replaced it with carbon core honeycomb and coosa composite. The prop selector recommend an 11 pitch prop for my estimated weight and boat type. Which I put at around 850 with motor batteries and fuel. Add the weight of the two fisherman and your over 1300lbs in the boat.
 

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If the motor is still sitting like it is in the original photo, you need a Powertech SRA3 10/11 pitch and a compression plate, it will plane. Those 35 Johnson’s are rated at 30hp at the prop.
 
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