# Question about UHMW and poultice corrosion



## PSG-1 (Nov 18, 2012)

When I do my next jetboat, I plan on installing UHMW panels for some added peace of mind. But since I operate primarily in salt water, I have concerns about poultice corrosion, from water being trapped between the UHMW and the hull of the boat.

How do the guys with UHMW on their hulls combat this problem. I know most of them are running in freshwater, but even freshwater will take its toll over enough time.

So, how do you combat this? Seal all the seams of the panels, as well as all the bolt heads? Use standoffs welded into the hull, to keep the panel spaced off by 1/8" - 1/4"? Use a good layer of epoxy primer and bottom paint? Just curious, for my own future reference. :?:


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## Scottinva (Nov 20, 2012)

Mine is not used in saltwater and is just screwed not my hull. I have heard of people using a caulk but am not familiar with it. I did not install mine, it was installed by the builder.

Scott


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## Jim (Nov 21, 2012)

Good question! Looking forward to hearing how this works for people who use their boats for dual purposes.


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## Ranchero50 (Nov 28, 2012)

I think the sealing decision falls under your hulls expected lifetime and how fast you expect the corrosion to eat through the aluminum. I'm more concerned about the stainless fasteners corroding the aluminum than minerals. I think a decent epoxy coat on the hull would keep most salt corrosion away except where the fasteners were. 

On mine if and when I UHMW it I plan on using 1"x.125" angle to act as standoffs on the edge of the original bottom strakes. I'll drill / tap / epoxy the material to the standoffs and leave the 1.25" gap between the hull and the material. It'll be open at the front and rear so hopefully the space will drain quickly on launch. I also thought about drilling some angled 3/8" or 1/2" holes to act as air inducers / water drains (ala hull steps) to lessen the wetted surface on the UHMW. With the gap I'll still be able to flood and wash out the space as needed.

Jamie


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## PSG-1 (Nov 29, 2012)

Yeah, that's what I was thinking. If/when I do mine, I'm going to make standoffs out of some solid round aluminum stock, drilled and tapped, but not all the way through, just blind-tapped, and then use a bottoming tap to cut the threads. 

Then drill holes and weld these standoffs into the hull, where they stick out just a little bit. I figure if I keep it spaced about 1/8" off the hull on the front end, to about 1/4" on the rear end, that should give enough space where poultice corrosion can't set in, the water can drain out from between the hull and the UHMW. Of course, right before installing the UHMW, I'd paint with a good layer of epoxy and then anti-fouling paint.


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## Kevin Turner (Dec 23, 2012)

I wonder if Link Tech's epoxy/UHMW process would be the answer? Pricey, but will keep the salt away from the alum...

https://linktech-inc.com/web/home.html


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## PSG-1 (Dec 23, 2012)

Interesting. This may indeed be the best option for me, considering the salt water use. Might even be worth seeing about getting it done to my existing jetboat.


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## Roost (Dec 24, 2012)

Id use uhmw epoxy, ss fasteners and not worry about it. Over time I would imagine some water would get between the uhmw and hull But if you do it right with epoxy + stainless steel fasteners to a .190 bottom I think it would take an awful long time before you'd have serious corrosion issues.. Just my thoughts


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## PSG-1 (Dec 24, 2012)

Yeah, I think with the 3/16" (.1875-.190") thick hull, it wouldn't be too much of an issue, not for a long time, as long as I used standoffs, and paint the hull with good primer and epoxy (like interlux) before installing the panels.

But for my existing jetboat, with its 15 year old .100" thick hull with previous corrosion damage, I think the linktech UHMW epoxy may be my best bet for some added insurance against abrasion or punctures.


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## Roost (Dec 25, 2012)

PSG-1 said:


> Yeah, I think with the 3/16" (.1875-.190") thick hull, it wouldn't be too much of an
> But for my existing jetboat, with its 15 year old .100" thick hull with previous corrosion damage, I think the linktech UHMW epoxy may be my best bet for some added insurance against abrasion or punctures.


Yeah true.. Besides epoxy how are you planning to fasten uhmw to your .100 hull? I talked to two different builders that wanted nothing to do with uhmw on my .100 hull. They said they would only do it if I replaced the bottom with .190


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## PSG-1 (Dec 25, 2012)

I don't think there is an easy way to install actual UHMW panels on my existing jetboat, that's why I was thinking about the UHMW epoxy application. In order to install actual UHMW panels, I would have to go back and install standoffs, etc, and that type of thing should really be done before the entire boat is put together. 

Kinda hard to go back and weld all those standoffs in there when you have fuel tanks, foam, etc already in the boat.


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## Roost (Dec 25, 2012)

PSG-1 said:


> I don't think there is an easy way to install actual UHMW panels on my existing jetboat, that's why I was thinking about the UHMW epoxy application. In order to install actual UHMW panels, I would have to go back and install standoffs, etc, and that type of thing should really be done before the entire boat is put together.
> 
> Kinda hard to go back and weld all those standoffs in there when you have fuel tanks, foam, etc already in the boat.


Gotcha. I probably missed some stuff along the way. Excited to see how you make out.


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## PSG-1 (Dec 26, 2012)

I got a quote for about $8K to do my boat. :shock: A bit steep for my wallet, even though I'm sure this would make my hull last forever.

Well, if my hull ever looks like it's starting to fail, I may just have to try my idea of welding in the stand-offs and installing UHMW panels, and maybe see about getting the tool/welder to weld the seams together.

And if I ever build another jetboat, the UHMW will be the first operation, before anything else gets done.


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