Boat insulation

[CapnK]

I'll be insulating my hull, and have looked at a number of materials. Sheet foam was what I'd been planning to use for a long time, but I've been beginning to wonder if something along the lines of Reflectix (plastic bubble wrap with foil on the outside, basically) might be the better solution.

Reasoning:

• Weight - the bubble wrap is lighter than foam
• More airspace means better insulation, and also more flotation per area

Reflectix has a built-in radiant barrier in the foil, but I could easily add that myself to foam sheets. What I am really thinking is to use plain bubble wrap and regular aluminum foil, since to do it that way would cost about half of what Reflectix costs, with very little extra effort.

Whatever material I use, it will be encapsulated between the hull and an inner liner of sorts, constructed by placing small ribs against the hull approx every 2', ribs to serve as a mounting platform for 'caps' made of glassed 1/8" door skin. In their end form, these caps will be removable, if absolutely need be, but pretty much sealed permanently with caulk/adhesive so that they are air-and water-tight.

From what I've read, such a sealed area prevents the forming of condensation and attendant mold/mildew problems. I'm thinking to try them for a year with just a foam strip sealing them temporarily, then peel one open, and see what has happened in the meanwhile. :)

Does anyone here have real-world expertise in insulation, and would care to comment on this? I don't want to get all involved in it only to find that I've made a mold factory against my hull. ;D

[AdriftAtSea]

CapnK—

From your description, you're basically setting up furring strips and are going to panel over the overhead and ceiling surfaces of the boat with 1/8" epoxy/fiberglassed door skins and fill the space between with bubble wrap and aluminum foil. 

What might work better is if you actually laminated the aluminum foil to the backs of the door skins.  That would make the foil much more simple to manage and reduce the chances of damaging it during the installation process.  Then, I would put up several layers of plain bubble wrap over the hull to fill the gap.  The reason I think you would want several layers, is so that the gaps between the bubbles can overlap, much like the quilted sections on a good winter sleeping bag, and provide you with a more even insulation layer.  You could use double-sided tape to hold the bubblewrap pieces in position. 

I did something fairly similar to what I proposed above to an old trailer a friend had and was using as her "summer" home. :)  Of course, the purpose of doing it to the trailer was to help reduce the heat getting in, not the keeping the heat in, and the foil was laminated to the exterior walls, not the inner liner.

My understanding is that regardless of how good a job you do with the caulk, the area behind the panels will still have condensation problems, and that you're best off not sealing the areas, so that any condensation that does form can drain or evaporate as necessary. 

[CapnK]

Actually, I'll have foil tight against both the hull and against the inner liner - for max radiant protection in both directions. The bubble wrap will be put in to fully fill the area between the foil layers. I considered the use of some sort of adhesive to hold it in place, but feel that I cannot count on said to hold up over a length of time, so instead I'll have the insulation hold itself in place with friction (ie; packed in tight).

It was a gov't or industry website of some sort regarding insulation was where I saw the info that if the space between insulation and outer wall is sealed tight and cannot breathe, that no appreciable condensation/mold/mildew will result. This would be useful as well towards my goal of using the boat as its own lifeboat (positive flotation).

A mere wondering that needs more research: wait for a low humidity day to seal up the areas, and throw in a few of those silica desiccant packs to soak up whatever moisture gets trapped inside when sealing.

[AdriftAtSea]

The double stick tape is more to hold the bubble wrap into place until you can get the paneling installed.  If you aren't using enough bubble wrap to fill the entire space, you're not using enough. :)

[psyche]

Capt K,
When I refit my Columbia 8.7 we epoxied firring strips to the ceiling and I put reflectix in the space and then screwed beadboard panels painted with brightsides with a flattener over the strips. Last summer I could tell a difference in the interior temp of the boat.  I was very pleased with the results. I think there was a lengthy discussion about insulation on the Columbia yahoo website. I think there is a difference when the foil and bubble are made as a unit then doing it separately. Also the foil is not the same as aluminum foil. Dan

[Lynx]

In order to prevent the mold, I would look into spraying the area with something like Liquid Lysol before putting up anything.

Carpet can be fast and cheeper but you may have to replace sooner. The Mac 26 comes stock with it and so far, I have had no problems.

[CapnK]

Thx for the replies thus far. :)

Psyches post made me do some more looking around, and I ran across this link really soon after starting:

http://cruisingresources.com/Hull_and_Deck_Insulation

So far I've not found the Columbia forum-specific info. I'm interested in seeing if they say foil actually won't work, or that it is just different. I'm fairly certain that Reflectix has an aluminum-coated mylar that acts as a radiant barrier. This is the same thing as 'space blankets', so I could use them for the same purpose. At $1 each (and even cheaper, if I look around, probably), at least it's not financially overly burdensome to have to do so. :)

James - I wish that I could do this as easily as carpet :), but since I am looking to get insulation and flotation from whatever I wind up using, carpet is a no-go in my case.

The search continues... ;)

[CharlieJ]

As you know Kurt, we used foil both sides urethane foam sheets behind the ceiling on Tehani. Our ceiling is roughly 3/8 thick ash, with gaps of roughly 1/16 between strips. We see no indication of condensation behind the ceiling.



Plus the foam was reasonably inexpensive, being a regular commercial insulation product.



We used the same foam as insulation around our ice chest, which as you may recall, kept  the remains of a block of ice from the time we left Texas until we arrived in Florida 11 days later. That is 4 inches where we could and 3 1/2 other places. All seams taped and foamed.

I would never ever glue carpet to the interior of one of my boats, even though I sell boats that have it and have installed it in others at owners insistance. Should it get wet, it STAYS wet for a LONG time and contributes to dampness inside the boat in cooler weather.

[AdriftAtSea]

Charlie-

I think the reason you're not seeing condensation issues, is because you have those 1/16" gaps between the boards.  CapnK is looking to seal the edges all around...and unless he manages to make it truly air-tight, what I see happening is the space between the hull and the panels acting as a moisture pump as it heats and cools—much like what happens to an unventilated boat in the cooler weather.

[LauraG]

I think the reason we are not seeing condensation is because any condensation would occur between the hull and the foam, not between the foam and the ceilings. There very well may be a mold factory going on back there but I don't know. The foam was stuck to the hull using contact cement so I am guessing that there is very little air space or room for water to collect. Don't know anything for certain except that my bed never gets wet from condensation dripping from the cabin sides.  :)

[CapnK]

I did some reading up on just what causes condensation to form, to make sure I understood the process. I did, so that left me trying to figure out if bubble wrap could be used in a manner that would keep it from happening.

If the area the bubble wrap was in was completely sealed and enclosed, the only moisture that could condense would be that which was sealed into the cavity at the time of sealing. I think that bubble wrap could be put in exact enough, and tight enough, to make that a very minimal amount, not enough to worry about. But then again, mold/mildew doesn't need much water at all, so maybe a little is too much.

However, being a very small volume of air, I think sticking in a desiccant pack would take care of that. It would be neat to try. :)

But, when I went to the store today, they had neither Reflectix nor large bubble bubblewrap, so I came away with sheet foam, and I'll be doing it as originally planned, much like what CJ & L did. :)

[AdriftAtSea]

CapnK-

One problem I see with sheet foam insulation... most of the stuff makes very toxic fumes if it burns. Of course, most times, if you have a fire on a boat, you're screwed anyways... so this may not be important.

If the area the bubble wrap was in was completely sealed and enclosed, the only moisture that could condense would be that which was sealed into the cavity at the time of sealing. I think that bubble wrap could be put in exact enough, and tight enough, to make that a very minimal amount, not enough to worry about. But then again, mold/mildew doesn't need much water at all, so maybe a little is too much.

After talking to a friend who builds boats, based on what he said...I think what causes most of the condensation is when warm air hits the cold fiberglass.  So, if you glue the bubblewrap to the hull fairly tightly, the condensation should be minimal... however, you probably don't want to seal the areas containing the bubblewrap completely, in that you want any condensation that does occur to be able to drain or evaporate. 

[Fortis]

They showed us a training film in Coast Guard. It may be on You Tube too. It is of fibreglass buning in a vaccuum. You set it on fire, once the resin itself starts to burn you take away all atmosphere...and the stuff outgasses enough oxygenating gasses as it heats and burns that it self maintains until something liek 85% of it is consumed...Losing 85% of your boat constitutes a BAD DAY.


our fire fighting policy on fibreglass boats is to dump on almost enough water to sink them...and if they are still burning, either fill em up and complete the sinking or get out of there and let them burn to the waterline, before towing in the remains so it does not obstruct traffic.
Nothing else to be done.

Alex.

[AdriftAtSea]

As I said Alex.... if your boat catches fire, you're screwed anyways.... :)  Just curious as to how many here on Sailfar sail a boat other than fiberglass or wood composite?  My guess would be that none of the boats on Sailfar are Ferrocement, Steel, or Aluminum, since these materials are generally used in larger boats than are typically found on this site.

[CapnK]

I think what causes most of the condensation is when warm air hits the cold fiberglass.

Right, condensation is simply the physical manifestation of air cooling down. As air cools, it loses it's ability to hold moisture, so that moisture will get deposited on whatever cool surface is nearest - in the case of a boat, that's usually the hull (especially if it is uninsulated).

In a house, you'll see condensation on the (thin, cold) windows, but not on the wall right next to it. The wall is insulated too well for that to happen.

That's why if CJ & L had condensation it would be on the backside of their foam against the hull, not on the side where their ceiling strips are located. For their sake, I hope there isn't enough room for that to be happening. :)

Regarding fire - on a boat this size, there's not much room to get away from it. I think if I have a fire that gets to the point of burning my hull insulation, I will have other worries than some toxic fumes. :D

Alex - very interesting info about the fibreglass burning.

[Auspicious]

I think what causes most of the condensation is when warm air hits the cold fiberglass.

That's why if CJ & L had condensation it would be on the backside of their foam against the hull, not on the side where their ceiling strips are located.

Excuse me for being late to the party. Reading the Gorilla Glue thread and then tracking back here, I keep worrying about mold production. Laura's point is well-taken -- you won't know what is back there. I think some more thought should be given to getting full adhesion to avoid air/vapor space. I think contact cement is a good choice, subject to material compatibility with the foam. I'd look hard for a spray application to make it easier to get complete contact across the entire foam panel.

[CapnK]

Dave - Agreed. I don't like the idea of having air being able to pass behind the insulation, if the insulation is pretty much permanently installed like I will have it. I've shelved the bubblewrap idea.

Regarding contact cement: I tested both tube/can liquid contact cement, and spray adhesive (like DuPont 77).

Forget the liquid stuff - it dissolves the foam much too fast, and is really messy to work with. The spray can adhesive can be used, with a couple caveats:

You have to hold the can far enough off that the accelerant/propellant/whatever it is mostly dries before hitting the foam. Even then, thicker applications will eat the foam a bit. So I used a different foam product, similar to CJ's (foil one side, plastic the other, covering EPS styrofoam), where the contact cement didn't actually touch the foam itself.

Found out that the problem with the contact cement stuff is that it just didn't do well against the hull. I applied glue, braced it in position for the recommended day, and it seemed and felt that it had stuck well. Within 3 days or so, though, it started popping loose in areas where the contact cement was not super-thick. I think the temperature change, humidity, etc kept it from forming a really tight bond. Maybe if I had used more adhesive, it would have worked better. But even the parts that I peeled off later did not seem to have nearly as good a bond as what I am seeing from Gorilla Glue - not a tenth of the strength, even.

That, along with the way GG acts (foaming to fill voids) makes it the best product I have tried so far for this particular insanity.

3M 4200 also did well, but again was very messy, and is a much more expensive alternative to GG.

[bayracer]

I will only say that if you take issue with air behind your foam, then you will not like the potential issue of voids if you do not get the foam completely bonded on the hull. After reading and playing catchup, the attempt of attaching cabinets to a sorryarrass layup of cheap foam with luan on its face that has such weak strength, you are wasting your time, energy and money on this project and procedure.

The first thing you do in the project is to determine the positions of your cabinet and any partisian builkheads and grind the glass on the hull and tab in structual strips and then buy some decent divinicell type foam and then use a slurry mix of cabosil and epoxy and stick this to the hull. The you can face the good stuff with some plywood of your choosing. Now where is my popcorn and morning java??? ;)

[CapnK]

So tell us what you *really* think!  :D ;) ;D

[bayracer]

So tell us what you *really* think!  :D ;) ;D

Well its a step above hearing about the doctor prescribing some pain killers and nerve medicines and having another two threads about how the boat has all these creaks with  misfitted cabinets and and the lose of another sailing season. ;)
Then again if you do not plan on sailing, just lay in your hammock sipping mnt julieps and slamming against the dock in unfavorable winds, then you should be okay.[insert tongue firmly in cheek and wiping the grin off of my face] ;D

In all seriousness, sometimes the first way is the cheapest way, especially since this is your home, right? Just my thoughts......

Darnit, I've run out of popcorn........