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Best Practices for Bonding Foam Bulkhead?

Old 09-15-2020, 06:03 AM
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Default Best Practices for Bonding Foam Bulkhead?

So Iíve been rebuilding this 23 Seacraft and Iíve chosen some new material (foam) to work with for creating this fish box. To date Iíve been using Coosa for the transom and bulkheads but I wanted to use this structural foam here for better insulation.

My question:
Should I bond the raw cut edge of the foam directly to the hull with thickened epoxy and then fillet and tab as normal or do I need to add some glass over the raw cut edge before bonding in place?
Same goes for the exposed edge that the deck will sit on. Does that need to be glassed to get a good bond to the deck or will I be fine to glue it down with thickened epoxy as I plan to do everywhere else?

My gut says just glue it in and proceed as normal.

I donít recall what the manufacturer and spec is on the foam but itís pretty strong stuff as foam goes.

FWIW- Iím planning on adding a couple layers of 1700 over each side before glueing the panel in place.





Last edited by Surfnski; 09-15-2020 at 07:31 AM.
Old 09-15-2020, 08:13 PM
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Love the work, brother!

I bonded mine using this:
https://www.homedepot.com/p/Loctite-...0594/202020474

stuff is amazing. I took 2- 2Ē squares for my thermolite (coosa type board), glued and clamped overnight then submerged in water. Had to put a lead ingot on it to hold it down. Checked everyday for 2 weeks. Still was bonded so tight I couldnít pull it apart And they floated.
Old 09-16-2020, 03:04 AM
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You're gut is correct, glue into thickened resin, filet and glass away! You can glass the panel first to help stiffen it if needed, then tab in. Or glass the panel in place and extend each layer as tabbing, either is fine. I use Divinycell H60 or H80 foam for all bulkheads and glass the larger ones first for stiffness but they are sometimes 18' wide or more and 15' tall, you're small one shouldn't have an issue.
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Old 09-16-2020, 06:19 AM
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Thanks for the replies guys, just the info I was looking for to make sure Iím on the right track.

The construction adhesive is an interesting idea and I may try glueing up a couple test pieces to experiment with but I think Iíll stick to epoxy as thatís what Iíve used everywhere else to date. I believe Iíve seen Bills use gorilla glue for glueing foam pieces together, I could see using the locktite for that application as well.
Old 09-16-2020, 06:24 AM
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Hereís a link to the work Iíve done so far if anyone is interested. I may start a rebuild thread over the winter once I get shutdown by the cooler weather as Iím limited to working outside.

https://www.icloud.com/sharedalbum/#B0UGWZuqDGxAc1p
Old 09-16-2020, 12:46 PM
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Originally Posted by Surfnski View Post
Thanks for the replies guys, just the info I was looking for to make sure I’m on the right track.

The construction adhesive is an interesting idea and I may try glueing up a couple test pieces to experiment with but I think I’ll stick to epoxy as that’s what I’ve used everywhere else to date. I believe I’ve seen Bills use gorilla glue for glueing foam pieces together, I could see using the locktite for that application as well.

yes, you need to glass over it. It’s just a bonding agent to give you a surface to work against. good luck on your project. It doesn’t really matter how you get there as long as it’s solid in the end. I’ve had very good results on my seacraft doing this.

ps it’s a fun experiment for sure.

Last edited by Xcomunic8d; 09-16-2020 at 12:57 PM.
Old 09-16-2020, 12:55 PM
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Originally Posted by Xcomunic8d View Post
yes, you need to glass over it. Itís just a bonding agent to give you a surface to work against. Iíve had very good results on my seacraft doing this.
Understood.

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