Hull insulation

[Torsten Hansen]

We are about to start a major refit of a blue water boat and we want to add insulation.

Does anybody have personal, long term experience with ArmaFlex or K-Flex closed cell foam for hull and deck insulation? I am especially interested in how you installed the foam, how thick your foam is, if you’ve had condensation issues? Would you use the same product again?

Thank you!

[coopec43]

Originally Posted by Torsten Hansen

We are about to start a major refit of a blue water boat and we want to add insulation.

Does anybody have personal, long term experience with ArmaFlex or K-Flex closed cell foam for hull and deck insulation? I am especially interested in how you installed the foam, how thick your foam is, if you’ve had condensation issues? Would you use the same product again?

Thank you!

Torsten can we ask what your hull is made of?

[Torsten Hansen]

Originally Posted by coopec43

Torsten can we ask what your hull is made of?

The hull is solid fiberglass, the deck is balsa cored.

[tkeithlu]

Torsten, I can tell you hat if I were refitting my steel boat, or your fiberglass boat, I would use closed cell foam. Wood would be another matter. Foam is applied by squirting the combined sticky liquids into place, where they react, produce gas bubbles, expand and harden. Once hard, the foam can be trimmed with a knife so that the interior finish panels can be mounted. BUT, remember that the foam encapsolates wiring and plumbing that runs through the spaces insulated. Encapsolating wiring in basically inflammable foam does not appeal to me. Not being able to remove and replace plumbing, ditto. So, think through what spaces you want to foam. I suspect you'll find specific advice from an experienced dealer.

[mako]

Might want to investigate the outgassing and curing period of the foam and more importantly, it’s flammability

[Torsten Hansen]

Originally Posted by tkeithlu

Torsten, I can tell you hat if I were refitting my steel boat, or your fiberglass boat, I would use closed cell foam. Wood would be another matter. Foam is applied by squirting the combined sticky liquids into place, where they react, produce gas bubbles, expand and harden. Once hard, the foam can be trimmed with a knife so that the interior finish panels can be mounted. BUT, remember that the foam encapsolates wiring and plumbing that runs through the spaces insulated. Encapsolating wiring in basically inflammable foam does not appeal to me. Not being able to remove and replace plumbing, ditto. So, think through what spaces you want to foam. I suspect you'll find specific advice from an experienced dealer.

Agreed, that’s what I would also if I had a bare hull. I spent the last 15 years specifying, selling and applying polyurethane spray foam and it works incredibly well. However, it is just not practical on this project so I’m looking at pre-made options. ArmaFlex and K-Flex have extremely low permeability ratings, which is crucial to control condensation. My main concern is the interface between the hull and the foam, how to adhere the foam to avoid air gaps.

[Torsten Hansen]

Originally Posted by makobuilders

Might want to investigate the outgassing and curing period of the foam and more importantly, it’s flammability

ArmaFlex and K-Flex are mostly used in technical insulation applications such as pipes and AC ducts. Fire ratings are good so that is not a worry.

[Strait Shooter]

I have personal experience with Armaflex.
I have a Colin Archer style double ender based in the Pacific NorthWest that I refitted, and I used 1” Armaflex on the Fiberglas hull, and cabin top. I used regular contact cement applied properly to both surfaces, when dried, push the two together and it eliminates any air voids quite well.
It’s been four years now, and it was one of the best choices I’ve made on this boat.
It’s also very spendy!

On edit, absolutely no condensation problems with it.

[NSboatman]

You’re right about the adherence and air flow control. I have a steel boat with mostly spray foam insulation; except I replaced some plate in a few areas and decided to try out the armaflex rather than re-spray.

I did not do a good enough job with adherence; and the result was terrible. Hidden pooling of condensation and mould growth. I ripped it all out, repainted, and sprayed with fresh foam (small contractor kits are easily found). Never trying that again- it is really tough to get a good seal retroactively. And a good seal against airflow is critical.

YMMV...

[NSboatman]

On the plus side, I have found that the 1” thick armaflex makes a fantastic, insulating underlay for our mattresses in our tent trailer!

...also used a few lengths to bulk up the underside did our cockpit cushions. Works well there too- but there are likely much cheaper options!

[pcmm]

Armaflex is great insulation but I'm not sure its practical to use to insulate a boat with. I'm in the process of doing that ground work now and investigated Armaflex, but to insulate my boat ( 41ft sailboat) would have cost me over $2000. The stuff where I am is $700 PER roll. Instead I'm using 3/4" EVA foam tiles for my insulation (I'm going to be a cold climate liveaboard again)

[Torsten Hansen]

Originally Posted by Strait Shooter

I have personal experience with Armaflex.
I have a Colin Archer style double ender based in the Pacific NorthWest that I refitted, and I used 1” Armaflex on the Fiberglas hull, and cabin top. I used regular contact cement applied properly to both surfaces, when dried, push the two together and it eliminates any air voids quite well.
It’s been four years now, and it was one of the best choices I’ve made on this boat.
It’s also very spendy!

On edit, absolutely no condensation problems with it.

Thank you, Strait Shooter! That was exactly the kind of information I was looking for. I appreciate that you took the time to reply. Did you consider the peel and stick version? It would be faster but I’m not sure if I trust it in this application.

[Torsten Hansen]

Originally Posted by pcmm

Armaflex is great insulation but I'm not sure its practical to use to insulate a boat with. I'm in the process of doing that ground work now and investigated Armaflex, but to insulate my boat ( 41ft sailboat) would have cost me over $2000. The stuff where I am is $700 PER roll. Instead I'm using 3/4" EVA foam tiles for my insulation (I'm going to be a cold climate liveaboard again)

Cost is always a concern, of course. I am not familiar with the tiles you are using but be sure to check the vapor permeability. You want to be as close to zero as you can get. Let a know how they work out. Stay warm.

[Strait Shooter]

Originally Posted by Torsten Hansen

Thank you, Strait Shooter! That was exactly the kind of information I was looking for. I appreciate that you took the time to reply. Did you consider the peel and stick version? It would be faster but I’m not sure if I trust it in this application.

I did consider the self sticking adhesive, but I did not trust the adhesion either. The contact cement rocks in this application.

I spent 1800 on a 38’ boat and that was the hull to below the waterline, cabin top, tonnage deck in the v berth.

I can’t express the satisfaction I’ve gotten from insulating this way. Between that and a diesel stove, I’ve been below zero and in my shorts

[Torsten Hansen]

Originally Posted by Strait Shooter

I did consider the self sticking adhesive, but I did not trust the adhesion either. The contact cement rocks in this application.

I spent 1800 on a 38’ boat and that was the hull to below the waterline, cabin top, tonnage deck in the v berth.

I can’t express the satisfaction I’ve gotten from insulating this way. Between that and a diesel stove, I’ve been below zero and in my shorts

That’s how I feel about the self stick, this is not an installation that can easily be redone. What brand of adhesive did you use?