Hull insulation in 2024

Trying to make sure I've run down my options and haven't overlooked any modern methods or products.

Have 2x boats that need in hull berth and dinette areas insulated. One is a new construction fit out, another is a retrofit in a boat that was only summer used but is now getting winter work and needs the bunk area to be less frigid.

Both are or will be stripped to bare solid glass. Area is 4 berths in a bow area on boats 16 feet wide with about 7.5 feet from floor to ceiling so not a crazy amount of surface area. Summer boat had mascoat like substance with marine carpet affixed, kept the sweat down but was treacherous to roll into mid January. In 2021 we did paneling over spray foam but on a much larger boat. I've seen a few with neoprene rubber and then carpet, some sort of foam plus a bedliner coating. Usually the diy looks janky and having seen the liner option it looks terrible as well.

Leading solution is spray foam sanded back and coated in a layer of frp with seadek or marine carpet. However that's a serious time and possible weight commitment.

Any other options to get some r factor on a solid glass hull with about 3 inches of room for insulation?

 

Are you familiar with pyrotek's stuff?

Military Approved Satin Weave Cloth, Sorbermide Coverings | Pyrotek https://www.pyroteknc.com/products/sorber/sorbermide-coverings/

 

Looks kinda like the acoustic panels we used back when engine rooms and hydraulics were nearer the living spaces.

 

There are not that may options to choose from that you don't know about. The "neoprene rubber" stuff is probably ArmaFlex, a product of Armacell: Armacell: Armacell North America https://www.armacell.us/home/ Comes in a wide variety, including flame resistant and self adhesive. R-value is 4 per inch. You can contact cement anything you want over it, how good it looks depends on your workmanship.
In areas where PU foam isn't allowed ArmaFlex and mineral wool are the two standard choices.
The only "exotic" choice I know of is cork. It has one advantage,
if you can stand the look it can be left bare.

From the R-value perspective you have PU foam at R6-8/inch, or the rest at R4. It isn't easy to get the max performance out of PU spray foam, you need a top notch installer, and glass over it. Even so, the R value will decline in time, altough this isn't a problem for boats.

 

I'd fir it and lay in polystyrene then cover it with 4 mil plywood with precatalyzed paint. The challenge is of course furring it out.

But it need not be perfect, gotta run.

 

Was a heavier density than armacell, but there seen to be 101 different formulations and matching can be tough. I've used armacell stuff on insulated pipes for refrigeration systems, as they offer all manner of sizes.

Got a swatch of carpet, going to order some small batches of different high density foam rubbers to see how they bond. Be nice to not have the foam guy back, it's gone up significantly since 2020 to have the good stuff sprayed.