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coreywoodworking 01-09-2011 03:12 PM

Insulation: Reflectix or Sheet Styrofoam
I've lived aboard a Caliber 28' sailboat in Boston harbor the last three years and I'm amazed how much juice I use for the two oil-filled radiators. The boat isn't insulated; it's a plywood-cored deck. So I've taken down the fabric from the ceiling and removed the veneer ply from the interior cabinhouse sides, in prep for insulating.

I'd use either reflectix or 1/2" unfaced styrofoam boards (kerfed on the back to meet contours). Foil-faced sheet insulation may have an advantage as contact adhesives or hot glue may melt the unfaced styrofoam. I'd prefer the sheet insulation because then I can bond white laminate to it, thus finishing the interior sides and for removable ceiling panels. It will also form a more palpable thickness as I'm replacing several portlights.

My concern, and it's remote, is that if it catches fire, the fumes are highly toxic/caustic, though the reflectix and for that matter, the fibreglas may be equally toxic. Also, I haven't compared the R-values of the two -- I thought there might be other issues I haven't considered and about which you might know.

I'd appreciate any and all comments/guidance you might have on this process.

mitiempo 01-09-2011 04:17 PM

I'm going through the same process. Actually thinking about buying a roll of Reflectix tomorrow.

Reflectix is best used along with something else. It doesn't have a good R value but reduces 93% of the radiative heat transfer. My plan is to do a 3 layer installation in my V berth. There is a fiberglass grid that stands out 1" so I am thinking of reflectix/closed cell foam/reflectix.

Here are 2 links. My plan is the method in the first link.

The Frugal Mariner: Insulating your boat

Capt'n Pauley's Virtual Boatyard -- Projects Galore!!!: Installing Insulation in Your Boat

Hope this helps.

Faster 01-09-2011 05:28 PM

I think it's quite important to use 'closed cell' foam here... regular styrofoam board generally isn't and will absorb any moisture it's subjected to - even if just through condensation.

Years ago we did a smaller boat with Ensolite - similar to the sleeping pads campers use. Indeed these pads can be an inexpensive source of closed cell foam but they come in smallish sizes. We bought our ensolite in bulk from a mountaineering co-op at the time.

Are you certain your entire deck is plywood cored? I'd not be surprised to find strategic plywood sections, but for a boat of that caliber ;) I'd expect to see mostly end grain balsa or something more appropriate than plywood.

MacGyverRI 01-09-2011 09:39 PM

I already glued 1 layer of the Reflectix on my boat (a work in progress), including inside the storage areas/cabinets etc., intending to get new Vinyl fabric to cover it but after seeing the "strip plank" type installation noted above I'm now going to finish it that way.

The Reflectix has been doing a great job w/ just 1 layer (R 5?) and I'm only using "1" 20 lb. propane tank every 7-10 days and keep my boat 72-74 avg. inside w/ winter lows that avg about 15F here in Rhode Island.

On the bottom of settee's storage area, I used 1/2" foam carpet pad and it also made a difference but I may change that out w/ some closed cell.

This is a mailorder closed cell foam page, but they sell all types of foam, including custom cut (V-Berths etc.), really reasonable. Poke around, they have lots of deals.
closed-cell foam, slow recovery memory foam, qualex foam, polyethylene, neoprene, polystyrene, EPS,

mitiempo 01-09-2011 10:30 PM

1 Attachment(s)
Reflectix is not R-5. Below is a chart from Capt'n Pauley's site I linked to above. That shows it at 2.38/inch. It is about 3/8' thick so R value is .89 for 1 layer. Note that several of the foam types listed are R-5 or better. I like the Reflectix/1/2" closed cell foam/Reflectix method and will use it in my V berth area. The foam I use is Ethafoam, a flexible closed cell foam that is easy to cut and glue in place.

sailingdog 01-10-2011 11:49 AM

Another option is to use regular closed-cell foam insulation and then laminate mylar "space blanket" to the inner surface to provide additional insulation. I'd point out that most of the plastic/foam insulation will produce toxic fumes if burned. Cork is a better choice if you want to avoid toxic fumes. Aerogel is a good insulator, but expensive and difficult to work with. :D

QuickMick 01-11-2011 11:41 AM

would you guys use the same stuff in the engine compartment? im noticing a bit of a draft coming through there.

rmeador 01-11-2011 11:54 AM

I also live aboard in Boston Harbor (at Constitution Marina). Are we neighbors? Anyways, I have used the Reflectix on my boat and it seems to make a difference. My understanding of how those reflective type insulations work is that their R-value is dependent on the temperature difference across them. When there is a high temperature difference, more heat is being lost due to radiation, and it's the radiation they block, not conduction like other insulating materials. I'm not 100% sure that explanation is correct, so take with a grain of salt. I used my reflectix to insulate the lockers that the ducting for my Espar runs through. It has made the air coming out of the V-berth vent noticeably warmer. That's the only insulation I've added to my boat. My boat seems to have a lot of air spaces near the hull that I guess act as pretty good insulation on their own, since I'm plenty warm and only burn about 1 gallon of diesel a day.

Tim R. 01-11-2011 12:09 PM

I am a live-aboard on a Caliber 40lrc in portland , Maine and am doing the same thing. I recently installed an ITR Hurricane H2 heater which uses about 15gallons of diesel a week. One of the best heat savers I have installed is the clear shrinkwrap. It was 65 on deck at noon yesterday.

As for insulation, I installed some 1/2" Tuff-R from Home Depot this past weekend. It works fairly well next to the bunk(where the admiral sleeps) and inside one of the hanging lockers. Unfortunately it dents easily and is open cell. I am looking for an alternative.

As for the plywood cored decks, that is correct. Caliber uses plywood cut into squares and then tiled in epoxy throughout the deck.

mitiempo 01-11-2011 12:10 PM

I would use the materials designed for engine compartments instead of what is being discussed - not only will it help reduce noise but is fire rated.

Reflectix is good for radiative and a little bit of conductive, but the closed cell foams are better at conductive as the chart I posted shows. When installed and sealed around the edges the convective is taken care of as well.

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