Though I used 1/2" Armaflex AP closed-cell foam for the overhead and under the side decks, as previously posted, I am installing Reflectix insulation along the hull (click here for more info on the installation of the AP foam insulation). The most effective insulation would have been to use the AP foam on the hull but it is expensive and needs to be glued to the hull to be effective which I did not want to do--I want to be able to wash the inside of the boat out as required to keep it clean and smelling good. The next option was a fairly thick "blue board" (1/2" has an R3 insulation rating) but it is messy to cut and does not bend that well. Also, the 4x8 sheets are unwieldy and I not suitable for cutting the shapes inside the boat. It is also hard to fit into small spaces. Reflectix is much easier to use as it comes in rolls as narrow as 16". Though it does not have that good an R value when used alone (R1) it can be made to be more effective with a little more work. It's basically just a 5/16" thick double layer of bubble wrap with a foil laminate on both sides. The instructions state that for it to achieve maximum effectiveness one needs to create a sealed 1/2" air space on the radiant side. This would be very difficult to do on the boat What I decided to do was to make a somewhat flexible sandwich panel of two layers of reflectix with a 1/4" thick blue board (flex fold) between the two layers and seal the edges all the way around with tape. The panels are made to fit between the existing fiberglass ribs in the boat to which the ash ceiling strips are attached. Individually, each piece has an R value of one. Together they are at least R3 but I think there are probably some benefits to having a laminated panel with sealed edges. I suspect the R rating is around R4-R6. Regardless, the panels should make a big difference in keeping the boat warmer in the winter and cooler in the summer. Reflectix is easy to work with as you can cut it with scissors and it bends easily. Also, it will not hold water. I am only installing the panels down to the bunk boards above the berths and the counter top in the galley at the moment. These specific panels need to be installed now so I can install the ash ceiling strips. Later, when the the trim and plumbing systems are installed I will add more panels below the bunk boards that can be removed for cleaning. What I like about the panels is they can easily be removed for cleaning. The foil does not attract dirt nor do they absorb water. They are easy to wipe off. They seem pretty durable. Also, I suspect have foiled faced insulation running around the entire boat the Far Reach will have a significantly improved radar signature. I bought all the supplies at Lowes. The Reflectix runs about $16 per 50' roll. I am using very sticky Gorilla duct tape ($9.00 for 35 yard roll) and I am experimenting with a roll of 3M silver HVAC metal tape ($15.00 for 50 yd roll). The flex fold blue board is $45.00 for 25 panels of 2'x4' boards. So far I have used four rolls of Reflectix, two rolls of Gorilla Tape and five blue board panels . . . or about $90 invested. I think it will end up costing about $300 to insulate the entire boat down to the bottom of the lockers (not including the overhead which I insulated with Armaflex AP Foam. This seems like a very good investment to me. It has only taken one day to do about 1/3 of the boat.