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Discussion Starter #1
I have lowered the engine as far as it goes with my Vance jackplate. Unfortunately the DF20A on the back of my LT25 cannot go any lower as the clamp handles will not allow it.

The boat will get on plane if I tilt the engine down slightly. It will plane fine until I try WOT, Then it cavitates.

So my options are as I see them:

- thinner piece of starboard on the jackplate, hopefully with a thinner piece I can still manage to clamp the engine down...it will be tight if I can manage it.

- spacers instead of starboard, I forgot where I saw them but that seems like a good option as well.

- hydrofoil - this intrigues me the most as they advertise the elimination of cavitation. I can get one from work pretty cheap and use one with a drill-less installation.

Anybody have any suggestions Besides those? I'm open to ideas
 

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I Love microskiff.com!
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This is the position I had to run mine in to keep it from cavitating. Doesn't look right to me.
IMG_0271.JPG
I tried a 4-blade prop and it didn't help.
 

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Sounds like the prop may not be cupped as needed? I do not believe the 4b prop will help only the opposite. Others on here know much more....
 
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Carpe Diem
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If you have to tilt the motor as much as shown in the photo, you're probably beyond the point where a different prop will help. I'd do whatever you have to do to get the motor a few inches lower. Your transom height is 16" and it looks like your jack plate has raised the motor another few inches. Coupled with a 15" shaft motor, your cav plate is probably an inch or two higher than it should be. With the motor trimmed with the thrust axis parallel to the keel, the cav plate should be about an inch (give or take an inch) above the line of the keel for best performance.
 

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Discussion Starter #8
If you have to tilt the motor as much as shown in the photo, you're probably beyond the point where a different prop will help. I'd do whatever you have to do to get the motor a few inches lower. Your transom height is 16" and it looks like your jack plate has raised the motor another few inches. Coupled with a 15" shaft motor, your cav plate is probably an inch or two higher than it should be. With the motor trimmed with the thrust axis parallel to the keel, the cav plate should be about an inch (give or take an inch) above the line of the keel for best performance.
With that said, would adding a hydrofoil help? I'm not disregarding what you've said, I'm well aware it is higher than it needs to be but the problem is I cannot lower it any further. I'm wondering if that hydrofoil will keep enough water on the blades to combat the problem.
 

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Carpe Diem
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A compression plate (hydrofoil) might help, a different prop might help, but you'd be throwing money at your problem and probably not fix it. It's hard to imagine that a boat would be built such that with the proper motor mounted properly it wouldn't run right. Is the jack plate necessary? Maybe it's the reason the motor is too high.
 
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A compression plate (hydrofoil) might help, a different prop might help, but you'd be throwing money at your problem and probably not fix it. It's hard to imagine that a boat would be built such that with the proper motor mounted properly it wouldn't run right. Is the jack plate necessary? Maybe it's the reason the motor is too high.
Another thought here, don’t just buy any hydrofoil type. A compression plate is what you need. The dol fins and the like will create lift and do not normally keep water around the prop. Like vertigo said, it the jack plate necessary? Your cavitating now, motor appears to be a couple inches too high. Jack plate appears to be raised only a couple inches. Remove jack plate, mount motor on transom. Problem solved?
 
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What prop is on this thing? Prop in picture looks tiny. Also, post some picture of it from behind so we can get a better look at elevation.
 

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Discussion Starter #14
Another thought here, don’t just buy any hydrofoil type. A compression plate is what you need. The dol fins and the like will create lift and do not normally keep water around the prop. Like vertigo said, it the jack plate necessary? Your cavitating now, motor appears to be a couple inches too high. Jack plate appears to be raised only a couple inches. Remove jack plate, mount motor on transom. Problem solved?
Yes...the problem is the jackplate is on there good. Removing it would mean removing half the gel coat off the transom as I can see what I believe to be 5200 on the jackplate.

Throwing parts and money at a problem isnt the best solution, but if I can avoid destroying that brand new transom and gel coat I'm all for it. I'll look into compression plates and at the same time prepare for the worst. Ain't nothing easy.
 
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There are a couple products out there that claim to break 5200’s bond. Debond and I believe the other is unhesive. I have never used them, usually by the time I get the boat it’s saw and grinder time anyway lol. If you try them let us know how they work please.
 

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Zephyr Cove is on FIRE!
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There are a couple products out there that claim to break 5200’s bond. Debond and I believe the other is unhesive. I have never used them, usually by the time I get the boat it’s saw and grinder time anyway lol. If you try them let us know how they work please.
Heat will break that plate loose if you hitch the trailer to your truck and use ratchet straps to put some constant pressure on the plate it will slowly lift off as you heat the jackplate. If that doesn’t work you could try a hot knife used to cut styrofoam to get between the plate and transom. If you think the jackplate is the issue or compounding the issue then it’s not doing you any hood leaving it on there. There’s nothing worse than an inefficient boat and motor combination.
A hydrofoil is a big trim tab that mounts to your motor, a compression plate covers more forward area and the sides curve down to compress water around the prop and water pickups and also acts as a hydrofoil.
 

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Carpe Diem
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Don't waste money on Debond or the other products that claim to release 5200. Been there, done that. 5200 can be cut off with a razor knife and sharp chisel, and then sanded. Otherwise dynamite and a flamethrower. Why people use it in semi-permanent applications is beyond me. There are plenty of good sealants out there that can be removed. Loctite makes a fast cure marine sealant that works fine and can actually be removed if the need arises.
 
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Thanks for clarifaication on the debond Vertigo. Like I said, I’ve never used them. The dynamite will work for sure!
 

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Maybe I am seeing something that doesn't exist.

It looks like your plate is above the transom and the motor can not be mounted at the proper height. If this is the case then remove the plate and mount the motor as originally designed.
 

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Zephyr Cove is on FIRE!
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Maybe I am seeing something that doesn't exist.

It looks like your plate is above the transom and the motor can not be mounted at the proper height. If this is the case then remove the plate and mount the motor as originally designed.
That’s why we are trying to help him figure out how to remove the jackplate.
 
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