AEROFLEX ROLL BOAT INSTALLATION
Because of the high thermal conductivity of aluminum it is imperative to properly insulate the interior hull surfaces, frames, stringers and trim edges. The main problem is condensation, which forms when the dewpoint of the warm moist air cools upon contact with a colder surface and changes from water vapor into liquid. The interior of a tightly sealed boat will rapidly approach 90-95% RH from sources such as our exhaled breath, cooking, evaporation from damp clothes and towels, bilge vapors, etc. Tight fitting insulation prevents the water vapor laden air from contacting the cold hull surface, thus preventing condensation from forming. Of course, the other equation is keeping the moisture levels as low as possible, achieved through adequate fresh air ventilation even on cold days is vital.
Loose fitting insulation such as the familiar fiberglass bats used in a house will not do for a boat for two reasons: They are not vapor barriers and they will absorb and trap moisture, eventually becoming sodden. Aeroflex Closed Cell Foam Insulation is the preferred marine insulation. The spray type polyurethane foam is convenient, but messy, and over a long period of time (years) will absorb moisture. The surface is fragile and difficult to repair-the guy with the foam rig in his van is long gone when you need to scrap away a section to weld in a bracket…
The system is comprised of two parts: An initial coating of Mascoat DTM, a ceramic insulating paint which is primarily designed to prevent condensation from forming. It is sprayed with a special cup gun in 2 coats to a thickness of about 30-40 mils (.030-.040”). The gun I purchased from Mascoat has a right-angle nozzle which is ideal for spraying on the back side of the Tee stringers. The stuff is non-toxic, cleans up in water and is incredibly sticky. Once dried on a surface it is remarkably difficult to remove. Spray the stringers, frames, chainplates, hatch landings, window frames and any exposed edges and areas that looked like I would not be able to cover with the other insulation. I did not spray it into the bilge area, as Mascoat advises that DTM should not be submerged for more than an hour or two.
INSTALLATION STAGE 2
The second component of the insulating system is closed cell EPDM rubber. 25mm thick Aeroflex Rolls. is a good thickness. Each roll is 1200mm wide x 5m long. Each piece had to be cut to fit its unique space between the frames and stringers. The best way to cut the foam is with a ceramic kitchen knife: incredibly sharp and durable. Cut the foam about 6mm smaller than the space. The Aeroflex foam will stretch or compress slightly, perfect fit isn’t necessary or wanted because there was ceramic paint on the hull around the frames and stringers, a slight gap wasn’t a worry. Pre-cut several frames’ worth of panels at a time, numbering them with a silver sharpie. Aeroflex Contact Adhesive, to install use a 200mm wide disposable foam rollers and plastic trays made applying the contact cement a breeze. It is vital to have good ventilation, both supply and exhaust. Carry out this job in mild weather. Hot and humid can be miserable. After trial and error (always) determine that sticking the middle of the panel to the hull first, then working out to the edges is the best approach. Contact cement can be frustrating because it is so tenacious; once it’s in contact, that’s it, take your time.