[QUOTE=MedicineMan]...but I'm thinking about a tube longer than it needs to be and a [roll top closure] then when rolled down to the calculated length it needs to be to work as a sleep pad it is then 'pressurized' to give support.....the roll top closure you are familiar with in dry bags used in kayaking....it is then not a valve to fail, not a metalic machine to fail, gives a opening the same opening size as the tube itself for filling/stuffing/ and insulation removal or addition.

Point me to a web site where I can see what you are talking about. [roll top closure] I have a few copies of Sea-Kayaker but didn't see anything in the "add's" section like you are talking about. I do think I have see the closure thing you are talking about, just can't find it now.

I see no real reason why your idea for the Primaloft will not work. I would like to get some Polarguard "D" (I think that is the one BackpackingLight.com is using for the Cocoon Jacket they are working on) and try it in some "wet weather' gear.

As for the hammock there are a lot of ways to make it warmer. I want something simple, light and compact. I am going with Down because of the weight and I think I can pack it smaller than with a synthetic. I want as few parts as possible following the KISS theory. Just how I will end up doing it may only come after working through several different ideas. It also may not work but if it doesn't I hope it leads me to something that will.