Insulating the hull questions.

[ebb]

Kent,
There are other fun foam sheet plastics, one of which is Ethafoam.
It is a translucent closedcell bendy polyethylene. BUT we can't glue this more friendly foam to the hull.
Possibly there's a glue by now that we haven't heard about yet. It's way cheaper than ensolite. Used as packing material for shipping.
Requirement may be that the surface of the sheet be pretreated with a propane torch to change its 'surface energy'
and then stuck on with a nice acrylic 'yogurt' paste. Haven't tried this myself !

Armacell also produces wax plastic (polyethylene p.olefin) insulations. They may have a waterborne mastic that sticks it.
NO aromatic solvents, OK? !

Ask the Armacell tech about gluing in the foam insulation he recommends
if it's not an ensolite.
The CLOSED CELL insulation must be firmly attached to the hull. Bonded.
Once it is embedded and bonded, no condensation will form and a good waterborne paste won't be a problem. If it's not continually immersed.
Ensolite in most ways is ideal because it conforms to mild concave surfaces. When gluing in, pushing it against the hull will keep it there.
This means the sheet won't tend to pull back into its flat sheet form (OR create a bulge) when gluing to the hull.... like other less docile foam materials. It's what makes ensolite the only closedcell foam that is also comfortable for expensive flotation cushions and bunk pads.

Also want the glue to bond to the rubber. It's possible that even regular contact cement can be pulled off the foam. Observed this once, it's not something I would swear to.
White carpet layer's paste is something to look into to. Acrylic glues are a minor miracle of sorts. See post #10, APAC 564.
(Defender & others have a liquid waterproof capet adhesive - not described as a paste - tech data sheets seem unavailable at any source. The origin of the carpet adhesive is Redrum Fabrics (makers of Nautilex marine fabric glue). Billed as non-hazardous. It works by
water evaporation in application, like 564, and other waterborne pastes. Forum user complains of material not holding on vertical surface.
Defender - Marine Carpet Adhesive - (Redrum Fabrics)Maple Leaf K-Grip 398, $34.99gal. Waterproof after cure. Is this roller or trowel???

[ I have the acrylic paste and the ethafoam, maybe I should do a test??? ]


You might be persuaded to use tube polyether or polysulfide. (Imco these structural adhesives, including tube urethane are WAY overkill) you'll still have to spred the material with a toothed spatula same as the yummy waterborne stuff - to get total no void coverage - and on both surfaces! Cost hundreds of dollars, and the cruds are viscous and messy to use.
There are no marine tube synthetic rubber caulks that will glue HDPE, polyethylene foam.
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[ Be warned and do your own confirming/testing. So far as I know this method is not supported by public forum. Nor Nigel, Larry, Maine or Don. Nor PracticalSailor or GoodOleBoat.
Personal research and luck (good & bad) led to the method, which seems logical.
And the inside of litlgull seems sucessfully insulated - from sheer to more-or-less waterline - with ensolite and a fine non-toxic cork&carpet paste.
This is.... in my considered opinion. ]