Linda/Steve, You are the woman and the man! I am building a 46′ aluminum Radford R14 pilothouse. Your specs on the FPB 83 note 1/2" Armaflex insulation on the hull – why not thicker insulation? Does your choice of Armaflex usher in a product that will become the aluminum boat standard insulation? Appreciate your reply. – John
Hi John: The question of insulating an alu. hull is complex. Here are our considerations:
1-As Linda is allergic to mold and mildew avoidance of these is the #1 requirement.
2-Sprayed foam absorbs water from the air and over time loses its insulating capabilities, in addition to which it is a great mold factory. Also, the foam continues to release unpleasant gases throughout the early years (or more) of its life.
3-We chose Armaflex because it has the lowest moisture absorption rate we could find. It is also very good on noise attenuation.
4-The 1/2" (12.6mm) thickness was chosen as it eliminates condensation down to about 20F at a 65-degree F interior temperature at a humidity level we think we can achieve. This is below where we ever expect to operate the boat.
5-More insulation would probably be warranted for colder climates, but for our purposes, when we looked at the heat load differential between 1/2" and 1", it did not warrant the extra cost, weight, or installation hassle.
6-We are using 1" material in the engine room for noise control. 2" is used on the watertight bulkhead into the interior.
7-We expect there to be a slight cost premium compared to a sprayed foam system, after taking into account clean-up costs with the foam.
Hope this helps – Steve
Posted by Steve Dashew (November 30, 1999)
