by andrewa » Mon 17 Oct, 2011 8:39 pm
Mark F,
I haven't calculated it out like you have. My prototype quilt, which I built a few weeks ago used ~250g of ~550 loft down and had an average measured loft of 4-6cm, albeit lightly filled, which is why I figure that 150g of 900 loft down would be similar fill.
More importantly, though, and I apologise for not making it clear in my initial comments, is that I sleep in all my clothes if needed - which includes Montbell thermawrap pants and Bozeman Mtn Works Cocoon Jkt (and will add recently aquired Montbell Ex-light down jkt to this), so I have a lot of added insulation if needed. I also carry a bivvy bag made from epic fabric, and have used this as an "inner sheet" when needed. Not sure whether this has any additonal vapour barrier effect.
Beyond this, I can post piccies of the shell, but, in my mind, until it's finished, it isn't that exciting! And, please don't enyone decide to make the same item and use it in the snow, and then get hypothermia. It is going to be part of my sleep system, which obviously involves a lot of other insulated gear.
Andrew A