15hp Cavitation Plate too low, how should I raise it?

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sej71

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I was curious what you guys think I should do...

The guy I got my boat off of raised the transom to accommodate a long shaft motor but he didn't raise it enough. He only raised it a shade over 2.25". When I measure it, my cavitation plate is 2" below my hull and I'm reading it should be anywhere from 1"-3" above. I'm losing speed and the extra drag is probably costing gas money too.

He reinforced it, and had these 1/2" boards on the inside and out (I wish I took better pictures of this b4 I took them off but you can see what I'm saying in the attachments). He cut away some of the transom to put in that raiser and I'm not sure how he's holding it cuz I do see a small gap but it's very solid. Maybe there's some deep screws under those metal plates beside it?

So I'm debating how to fix this to get the height right. Here are a few options I'm considering...

1. Buy this Mini Manual Jackplate - https://bobsmachine.com/product/mini-manual-jack-plate-mmj-0-40-hp-max-for-clamp-on-motors/

This would raise the motor 2.5" and i would also have another 1.5" of adjustable height. So it would put me 0.5" above the hull with no chance of going lower. But I does have 3 setback settings, 4.25″, 5″, or 6.125", so I could go back more if needed, they say the further back the higher up it has to go.

I like this idea even though it's kinda expensive, it's probably the best and most versatile way to go. I'm torn if I'd go straight against the hull with it or make a similar 1/2" wood board or aluminum plate on the transom first?

2. Take apart what the guy did to raise it and rebuild it 2"-3" higher. One problem with this is I don't have a way to cut aluminum or bend it nice like he did, so it's gonna cost to get someone to do this for me.

If I did go this way, should I do another 1/2" wood plate or aluminum on the back again?

3. Just rebuild the boards I ripped off but treat them (he didn't and they were rotting) and just leave the height issue for at least this year.

The problem with this is, if I build it exactly like he did I might not be able to add that mini jackplate later on without redrilling the transom. The bolt holes he did are right on what would be the edge of the jackplate. They have another mini narrow jackplate called the Versa that has 6" lift and only 10" wide but it's $350 USD :(


A few things to consider... The boat is about to get 2 coats to Fasco Steelflex Super Slick, so I'd really to take care of this and not mess with it again for a long while. I'm also converting this boat probably this offseason, so it'll be much heavier next year.

Maybe you guys have another idea or thoughts on what's best?

Thanks!
Shayne
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Sent from my SM-G955W using Tapatalk
 
i used one cant remember the brand but it was perfect for my application. pics of it in the my build thread. 12' sea nymph. i paid $75 for it. ill get the name off of it tonite
 
minijacker

https://www.amazon.com/T-H-MARINE-SUPPLIES-MJ-1-DP-Supply/dp/B0000AXQ9D/ref=sr_1_3?s=sporting-goods&ie=UTF8&qid=1527193770&sr=1-3&keywords=th+marine+jack

also these would probably work:

https://www.amazon.com/Marine-JP-4FA-DP-Hi-Jacker-Fixed-Plate/dp/B0000AXP0L/ref=sr_1_1?s=sporting-goods&ie=UTF8&qid=1527193770&sr=1-1&keywords=th+marine+jack
 
Ya I looked at that one but it won't work for me cuz it's 17" wide and I've only got about 12" at the top of the raiser that the other guy put in. Well, unless I mount it high and just deal with it being above the transom. That other one would be much cleaner, just wish it wasn't so expensive :(

Sent from my SM-G955W using Tapatalk
 
I got my Transom rebuilt finally. It didn't go as good as I hoped. I made a bunch of mistakes, even redid half of it once, thank God for Quick Aluminum Epoxy! Sigh, but it's done, for now. I think I might rip the transom completely apart and rebuild it when I do my conversion in the offseason cuz I discovered the guy b4 me didn't center his work properly and I built off it... My engine sits 1cm to the left in order to sit in the middle. I raised it another 2" to overcome my cavitation height problem. It seems extremely strong! I test it tmw
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Sent from my SM-G955W using Tapatalk
 
"My engine sits 1cm to the left in order to sit in the middle"

Unless my metric knowledge is WAY off, 1 cm (centimeter) is only 3/8th of an inch. I'd leave it alone and just enjoy it.
 

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