I had always wanted to try out the Gossamer Gear Night Light sleeping bag but found this Sierra Designs Wicked Light on sale for just over $100.00 a few months ago and figured I would take a shot at modifying it. Had some extra 0.33 Cuben from a few years ago that I figured would make a nice double layer sleeve to hold the BA Clearview pad in place and thought two layers might also help a little bit in keeping the heat in since there isn't any insulation in the bottom portion of the main body now. The older version of the 45 degree sleeping bag started out at 22.3 oz. I shifted all the down away from the bottom portion and the tubes plumped up very nice around 2.5" I then cut out and sewed closed the bottom section leaving the last three sections of the foot intact. Two of the bottom sections needed a little extra fill so I added about 0.90 extra ounces of 850 FP Goose Down to two of the three chambers. I bought a new lighter weight zipper to replace the one on the bag but looking at all the work it would have taken to remove and replace the zipper along with the zipper stiffner with something slightly lighter just seemed like to big a task to save about 0.5 to 1.0 oz. So, I didn't do it.
I really think I might be able to take this bag to mid 30's but I might be dreaming ??? Total weight after all the bottom mods and also cutting off the straps and replacing the neck seal cording with lighter weight cording only dropped the finished weight to 19.1 oz. but it sure looks like it is going to be warmer now.
Too many things I have made lately ... Time to quit making things and get out there and start testing them to see if they are better then before I started modifying them!!
Kevin

Nice!

Kevin,

Great job on the mod. It looks like a well designed system.

I predict that your 'new' 2.5" loft top-bag will keep you toasty, even below 30°, provided you place some closed cell foam to the top of your Clearview. The Cuben bottom will reduce losses to moving air, but not convective losses to the ground.

Do you (or anyone) have any experience on the puncture resistance of the .33 ounce Cuben? Just how careful must one be to keep it waterproof?

Thanks Greg. I built the nice quilt a few months back to take me down at and below freezing. This bag is really planned for trips where I think the temp will not drop down below 40 degrees but want the safety factor of being able to take it lower if needed. I just really need to get out and so some testing soon.
On the Cuben, I need to go back a few years and look at my records to make sure it is .33 Cuben. Pretty sure it is but I want to make sure. I think I bought that weight just after reading one of Bills post. I would search his posts as I think most or a lot of his projects use the 0.33 cuben. This is the same material that I used to build my 18.8 oz cuben mid three person shelter that I have used about 6 times in the last two years. Just one or two little holes that we fixed in the field with 1 inch duck tape strip until I got back home and made the simple repair. Plenty of actual testing in the rain confirms NO leaks or drips. Condensation can be your worst enemy though with cuben witout enough venting. You can definitely puncture this thin cuben if you aren't careful. Thinking my next two man shelter is going to use 0.60 cuben for a little added strength without much weight gain.

Edited by kegelhoff on 05/19/2009 12:07:16 MDT.