Boat insulation

[CapnK]

All thoughts are considered, and considered important. :)

I really think that 'floating' the interior on the foam core would work out OK for 99+% of sailing and conditions, provided care was taken in how it was assembled. During this discussion, though, I've been thinking about the book "Heavy Weather Sailing", and the stories related therein where it was usually the 'down' side of the cabin trunks which get stove in during serious breaking-wave broaches. That's the kind of impact and forces I want it to be able to withstand - Knowing there are no guarantees, of course.

The interior structure *will* be bonded to solid pieces of wood that were factory installed against the bare-glass hull, but not everywhere, in the case of a 'floating' interior. I really think that sheer surface area would be plenty strong enough for that 99+% of times. I think y'all are right - bonding key elements of the structure directly to the hull should take care of that other percentage.

Regarding the Luan - it will have glass on both sides, and is intended only to serve as a thin, high(er) density core material for the inner skin construction. It won't be the actual face material.

[bayracer]

What is your specific reason for glassing both sides of the Luan? Unless you use some structual glass, and then I am not sure the specific reasoning, finish cloth is nothing more than an abrasive coating.  Also if you go with glassing the luan or another type sheet plywood, why not use appropiate stuff thats along the lines of epoxy and fiberglass to include the good foam and good plywood that has appropiate sheer and compression strengths?


Your off the shelf big box luan seems to have pulp intercores now, which further weakens the panel that you are going to the pains to glass with the good stuff??? How many sheets do you figure that you will use in this job? The reason I ask I gotta thought.


Just curious

[CapnK]

The Luan or doorskin will simply serve as a high density core for the interior skin (at the hull), and the same in the outer skin layers of the 'board' material which will be used in constructing the cabinetry. The main strength it will lend is to make the surface more impact resistant; that said, it will also make the overall structure stiffer. I am using it instead of solid, heavier, multiple layers of glass mat/cloth.

The glass I will be using is the same cloth used on surfboards, which when used properly is indeed *very* structural. I am getting it from the guy I made boards with for a number of years, here and in Hawaii. I'm not unfamiliar with these materials; I made boards (and other composite structures, and did small boat repair, etc) as a living for a number of years. Also, many people do make hulls for small boats from these same materials.

This interior construction, structure that wasn't even in the boat to begin with, and which won't be used in making long stressed spans, does not have to be as strong as it would be were I building a hull, or using it as a needed brace for the hull. My intention is to replace the weight of comparably sized plywood (and whatever might be used to finish it), with a lighter weight, lower density foam core composite construct. Of course, I can use plywood, or extra strengthened foam core material, if the extra strength is needed for a particular component - say on a seat, for example. Conversely, in areas where the thicker skin is not needed, I can use plain glass over foam.

I've made test panels of simply foam and doorskin - with no glass - and found it is an incredibly stiff and light material even without the glass. Of course, it may not be as strong as if it were laid up of plywood and glass, but then - it doesn't need to be, and it is not nearly as heavy, which is the main point. Make some up sometime, test it, I think you'll be impressed.

I really have no idea how many sheets I'll be using, and the doorskin is a smaller size than the 1/4" Luan (3'7' vs 4'x8'). But as a rough idea I'd say 10 sheets, approx.

[Oldrig]

Hey Kurt:

You might want to look in the current (January/February 2008) issue of GOOD OLD BOAT. There's an article called "Facing a Winter Aboard."

It's all about how a live-aboard couple insulated their boat with 1/2-inch Celotex insulation (foam with reflective aluminum foil). It's a pretty complete description of how they cut and fit the stuff, and how they covered it (some with wall paper, I think, and some with a wood-strip ceiling).

Anyway, it would be worth checking it out.

--Joe

[CapnK]

Thanks Joe (Grog!) I'll look for that article. I used Celotex last year during the cold, and it worked well. If I was just dropping insulation in (vs glassing it to the hull), I would definitely have a layer of that, I like the radiant barrier it has. :)