I love sleeping under a quilt inside a bivy bag! I have read that 4 inches of loft is needed for a 0 degree rating. But at some temperature would a quilt reach a point of diminishing return? At what temperature does a quilt no longer make sense? Does the top bag start where the quilt leaves off?
Even though I love Bill Fornshell’s Sleeping Bag designs, I don’t know if I could sleep in something so narrow without a zipper. How much would the design suffer if the sleeping bag were made wider and with a zipper?
I purchased some Momentum90 some Cuben and 8 yards of Climashield XP 5 oz/sq yd. 1.2 inches of loft per layer clo=.82/oz. How many layers for a 0 degree quilt? Do I make it wider to tuck the edges under? Which quilt would you copy?







