The best choice? Ensolite foam or Armaflex has been used for many permanent installation, either self-adhesive or glued-on (contact cement or similar). Yes, it is more expensive, but you will do the job right.
* Flexibility will allow it to make full contact with the hull. This will eliminate condensation and mold behind the insulation.
* Non-absorbent, of course.
* Will deaden sound.
* Much neater.
I have a sneaking suspicion that a boat insulated with most anything else will have reduced resale value, as the surveyor will no it breeds mold.
Armacell: Lavranos 43' Sailboat, British Columbia, Canada
Made with Microban, AP Armaflex (www.armaflex.com
) is antimicrobial. It is resistant to mold growth, fungi, and bacteria. It is safe (will not contribute significantly to fire), durable, toxin-free (manufactured without CFCs, HFCs or HCFCs) and fiber-free. Water absorption is only 0.2 percent by volume. The closed-cell structure of Armaflex prevents moisture from wicking and makes it an efficient insulation with an R-value of 4.2 per inch of thickness.
Armaflex SA (self-adhering sheet and roll insulation) is a flexible, elastomeric, thermal insulation, with exceptional condensation resistance, as well as sound-dampening characteristics. It is matte black in color, and may be applied as a stand-alone material, without the need for a hull- or headliner to hide or protect it. The adhesive backing is aggressive and adheres extremely well to curved and uneven surfaces, which are properly prepped (surfaces should be cleaned and degreased; isopropyl alcohol works well).
Armaflex is manufactured and supplied in both self-adhering sheets and rolls, and non self-adhering sheets and rolls. Flat sheets dimensions are three by four feet, with wall thicknesses ranging from a half inch to two inches. Rolls are typically supplied in four foot widths of continuous lengths, with thicknesses ranging from three-eighths of an inch to two inches.
The one disadvantage of Armaflex is that it is expensive; ten times as expensive as Reflectix, for instance, and about three times the installed cost of urethane spray foam. However, Armaflex is very easy to work with and apply, and it provides a finished look when used in exposed interiors not already covered and protected by a liner. With ease of installation, and exceptional material properties, Armaflex makes a first-rate insulation for thermal control, sound dampening, and most especially, condensation control.