George
I like your idea of having the whole overhead easily removable (except that you’ll have problems doing this around the trim for the hatch covers and where the grab rails are attached, as well as any place where there are things attached to the bottom of the overhead that penetrate it…like lights and the little chains & hooks that hold up the opened portlights). The thought of (repeatedly) dealing with all those cut edges of the fiberglass sheets is enough to dissuade me from considering using them. Beyond that, it will reflect (rather than absorb) noises inside the boat. I think I’ll stick with the foamed pvc idea myself, and line the bottom of the overhead with “Reflectix” (foil coated bubble wrap) for insulation while I have the whole thing ripped apart.
I’d forget the industrial velcro if I were you. I don’t think you’ll be happy with the life of the adhesive on either the bottom of the overhead or the fiberglass panels. Heat, moisture, and the constant stress of gravity will have the whole thing down in your lap at some point.
What you want is the 3M Marine Reclosable Attachment System (Part 051135-06539) available at your favorite big-box marine stores and online here and there.
It’s way more expensive than the Industrial Velcro, but the glue is amazing. It uses little interlocking plastic protrusions on both pieces, rather than fuzz on one or the other.
You won’t need an entire strip at each attachment point. Stick two pieces together, cut them (together) into 1" x 1" squares (you’ll get 6 out of each package of four strips…about six and a half bucks per package at Jamestown Distributors). Maybe you can find a better bulk price.
Search NexTag for sources of larger quantities, cuz you can buy it in 150’ lengths if you want.
It may seem like a “Duh” kind of thing, but to install it, put the two halves together, peel the adhesive off of one side, stick it on either the overhead or the panel, then peel the adhesive off the other piece and press the panel to the overhead (like you would if you were using contact cement). Rubbing hard over the attachment points will seal the glue to the surfaces, but you may want to prop it up with your extendable boat hook with something to spread the pressure over the panel while the glue sets up a while.
I have no doubt that, with enough of this stuff, you could stick a loaded 48 quart Igloo cooler on the overhead if you wanted. I (over) used this stuff to attach a power strip to the (wooden) back side of an aquarium. When I later removed it to replace the aquarium, it was all I could do to get the piece off of the back of the power strip, and I’m sure that the bond to the wood was stronger than the strength of the wood fibers beneath.
