# Bonding the cap onto the hull



## SouthernAngler (7 mo ago)

What would you recommend for gluing the cap on to the hull ? Im getting closer and trying to plan ahead. I was going to use poly resin thickened with cabosil and some 1/4" fibers then try to do some glassing under the gunwale to the hull. I also thought about using 5200 to make the bond between the 2 parts then some glassing. 

The deck is made of foam core, glassed over with 1708. The hull is a old Johnsen hull with a rolled edge that the cap will rest on. All my work was done using polyester resin.


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## birdyshooter (Sep 17, 2019)

Thixo Flex Thickened Flexible Epoxy Adhesive


Thixo Flex Flexible Epoxy Adhesive forms permanent, flexible, waterproof bonds that withstand movement caused by changes in humidity, temperature, and load stresses. An essential part of any boat b…




www.totalboat.com


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## 17376 (May 5, 2017)

Plexus or make thicken epoxy. Once bonded glass a layer of tape under the gunnels etc


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## lemaymiami (Feb 9, 2007)

I'll be following this to learn more... My old skiff has the deck through bolted (a fastener ever ten inches or so...) and it is a pain to take apart when needed... Speaking of that, with a small hull that has a deck cap bonded to it.. how do you separate them if you need to remove a gas tank or do other serious hull work down the road? When you own an older skiff with lots of years and hard use on it you think about such things (and pray you never have to do them...).


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## Capnredfish (Feb 1, 2012)

*Also this.https://www.scottbader.com/wp-content/uploads/Scott-Bader-Marine-Guide.pdf*
The Crestomer product
Whatever you decide on. Test the product work time. You may need multiple friends with application guns/product to get it applied, deck set and leveled out.


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## Capnredfish (Feb 1, 2012)

lemaymiami said:


> I'll be following this to learn more... My old skiff has the deck through bolted (a fastener ever ten inches or so...) and it is a pain to take apart when needed... Speaking of that, with a small hull that has a deck cap bonded to it.. how do you separate them if you need to remove a gas tank or do other serious hull work down the road? When you own an older skiff with lots of years and hard use on it you think about such things (and pray you never have to do them...).


You cut access holes!


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## SouthernAngler (7 mo ago)

lemaymiami said:


> I'll be following this to learn more... My old skiff has the deck through bolted (a fastener ever ten inches or so...) and it is a pain to take apart when needed... Speaking of that, with a small hull that has a deck cap bonded to it.. how do you separate them if you need to remove a gas tank or do other serious hull work down the road? When you own an older skiff with lots of years and hard use on it you think about such things (and pray you never have to do them...).


Those are considerations but this is a fairly simple skiff, no permanent fuel tank ect. I don't see a reason and don't see it in my future to be removing the cap. If I had to there's alway a way. last resort a sawzall.


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## Mike Haydon (Dec 19, 2019)

I have already bonded mine bud. I used a product from FGCI. It's there FC-8 bonding putty. Basically thickened resin like you were gonna do. Doesnt have milled fibers. If you have the cash that thixo 2 part in the caulk tube would be great. It's expensive and you would need 2 for sure. If you make your own you can always put it into a ziplock and cut the corner off if your working alone. 

My cap is actually 4 pieces. Front deck, rear deck, then the sides. I kind of did like harry spear. I glassed the bottom, then bonded, then glassed the top to make all one piece. Glassed what I could from the inside as well.


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## Mike Haydon (Dec 19, 2019)

Dont forget to add some spacers so it doesnt all squish out. You want what ever you choose to be in there a little thick. Like at least an 1/8" .


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## permitchaser (Aug 26, 2013)

I’d screw it down with SS screws. Bob’s right you never know when you need to get under there. Screw down then put the rub tail over it


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## Flats Hunter (Jul 23, 2021)

I've done a lot of research on this as I am also at the same step in my restoration.

The general consensus among builders is that Plexus is the absolute best. It's very expensive though and requires a special gun. Im sure you could also use another MMA from ASI as well. The idea is that you want something that bonds well but also has a little "flex" to absorb any shear forces.


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## K3anderson (Jan 23, 2013)

I just did thickened epoxy with bubbles and clamped it with like 20 clamps. Once cured, glassed it where I had access. This was how Chris Morejohn said to do it. Seemed like he knew what he was doing so I did that


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## Sublime (Oct 9, 2015)

K3anderson said:


> I just did thickened epoxy with bubbles and clamped it with like 20 clamps. Once cured, glassed it where I had access. This was how Chris Morejohn said to do it. Seemed like he knew what he was doing so I did that


That is what I did as well. Be careful not to tighten the clamps so tight that you squeeze all the goo out. Also have a long straight edge to make sure you are not putting a bend in the cap and adjust clamps accordingly


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## NOALA50 (May 31, 2021)

Like @flatshunter suggested "The idea is that you want something that bonds well but also has a little "flex" to absorb any shear forces."

I have always had success with this companies products (both sililiar and dissimiliar materials bonding) and they typically return calls within 
one business day.









Marine Adhesive


H.B. Fuller's marine adhesives are designed to bond to almost any substrate without sliding for a secure weld mount application. Contact us to learn more.




www.hbfuller.si


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## jonny (May 1, 2007)

Be careful with your tolerances when using thickened epoxy. It’s brittle when used to fill bigger gaps. It also will get hot as hell when thickened. I mean as in almost about to burst into flames hot. I have used the freezer bags putting floors down for large mixes. And before I could squeeze it all out I could barely hold it with my hands. Ideally you want something that is designed to not fully hardened when cured. So you have some give to keep the bond. Busted out bonding putty is a very common repair I do at the shop. I picked up some new stuff I am going to try on my skiff to test out. Once I do the final cap bond. It’s Inter Mix 90 8422 it’s a epoxy urethane hybrid with 3500psi of bond with some flex. It already is thickened with fumed silica and glass bubbles. It’s much less expensive (less than $30 200ml)than methacrylate(which fails) and that stupid $500 glorified caulk gun. You do need a mixing gun though. But you can get them at commercial auto body suppliers for $30-70. Apparently the auto body guys are not suckers like us boat guys. That is until the SnapOn truck rolls up😂


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## Capnredfish (Feb 1, 2012)

What about good old West systems Six-10? I’ve used it a few times. Strong as hell.


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## Mike Haydon (Dec 19, 2019)

Capnredfish said:


> What about good old West systems Six-10? I’ve used it a few times. Strong as hell.


I couldnt find six-10 in stores anymore. May be able to order it.


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## JC Designs (Apr 5, 2020)

X’s two for the thixoflex. All are great suggestions and will work fine. The thixoflex will make life easy for you.


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## birdyshooter (Sep 17, 2019)

@SouthernAngler if you go with the Thixoflex, get a good high ratio caulk gun and cut most the tip off. Don’t cut it like you would to caulk trim or a bathtub. You’ll be in for a world of hurt if you do. It’s thick!!


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## Sublime (Oct 9, 2015)

I used Thixoplex in several areas. Good stuff and very convenient but super expensive. You’d be talking a few hundred dollars to do a cap.


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## gulfcoaster (Aug 8, 2019)

About to do the same on my boat. What about drilling holes in the cap for the epoxy to seep thru to help hold it?


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## gulfcoaster (Aug 8, 2019)

Mike Haydon said:


> I couldnt find six-10 in stores anymore. May be able to order it.


West Marine carries it


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## Mike Haydon (Dec 19, 2019)

gulfcoaster said:


> West Marine carries it


That's where I couldnt find it in stores. At least not in the nature coast and tarpon springs area.


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## gulfcoaster (Aug 8, 2019)

Mike Haydon said:


> That's where I couldnt find it in stores. At least not in the nature coast and tarpon springs area.


They have it i Mobile area, usually only takes a couple of days to ship over


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## Mike Haydon (Dec 19, 2019)

Cool, I will have to ask someone next time.


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## trekker (Sep 19, 2015)

Ive done 3 with US Composites slow epoxy(thickened) and they' bulletproof. Those are all epoxy boats though. Can't vouch for it being used to bond the deck to a polyester hull.

I have used it to mount a couple casting decks and floors to Gheenoes though and those boats have done fine. I'm pretty sure the Gheenoes are poly built.


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