Here are several options, Al
Al, I notice you're in Boston so I'm assuming that part of your concern is much like it is for those of us currently wintering in London aboard our boats: condensation and its consequences (mold, mildew) being delivered into the new covering, given the temp differential between the outside (and therefore the fiberglass hull laminate) and the (warm, heated) interior air in the cabin.Generally, contact cement is the poison of choice when doing this kind of attachment...but the 'catch' is that you'll need the surface dry (so you can't have the interior comfy and warm while it's cold ouside) but yet the working temp of the laminate has to be suitable for the contact cement. Ahhh...in other words, you'll need a warm(er) day or perhaps will need to wait until spring. If part of the laminate is below the water line, I'm guessing you'll have a temp incompatability problem.It sounds to me like you should consider attaching closed cell foam to the hull laminate first, and then overlaying with your covering of choice...or at least, that's what I'd suggest to the extent the area you are recovering is part of the living space and will be heated during the winter.Personally, I'd encourage you to look beyond indoor carpet choices. First, this is one of those projects that can - visually and functionally - either increase or decrease the value of the boat, and some folks will be turned off by indoor carpet. Second and from an aesthetic viewpoint, I think you can find more appealing materials that aren't that much more expensive and yet far lighter, which would help you when installing it. And finally, you might find a product that's treated against mold & mildew...or that you can treat yourself. Carpeting doesn't lend itself to this very well simply because we're talking a lot of surface area in those fibers.One last pointer: you don't indicate but perhaps part of the hull laminate lies beneath a berthing area. In that case, you'll have a warm body (with the warmth being contained by the blankets) interfaced with a cold air space just below the berth cushion, being cooled by the hull laminate and perhaps the water in which the boat sits. Water is 800X denser than air, remember. This is a guaranteed problem and you'll need to deal with the space under the bunk in some fashion, no matter if you have foam on the hull laminate or not. Just a thought, in case it's applicable...Hope that helps. Don't forget to post what you've learned when you've got the project wrapped up!Jack