Another Down Underquilt Plan - Critique Requested

I am planning a new under quilt and I would appreciate a sanity check of my planning and make sure that I am not missing something. I want to order down tomorrow.

The quilt is being made for a bridge hammock with center width of ~34 inches and 78 inches long.

The under quilt is a karo design with 12 inch blocks and 6 inch long x 2 inch thick baffles.

The finished dimensions of the quilt are 34x72x3 and will be made from 3 yards of .51 oz/yd cuben.

Planned loft is 3 inches. Fill is 9 ounces of 900 FP down, which yields about a 10% overstuff.

Amount of down = 34x72x3/900 = 8.2

Since the design almost uses all of 3 linear yards of cuben = 3x1.5(54”) ~2.4 ounces

Overall, I expect the finished weight to be 12 - 14 ounces.



For 3 inch loft is a 2 inch finished baffle reasonable to keep migration to a min.? Would 2.5 inch baffles be better?

I am thinking about putting a 12” slot in the middle of the quilt so that I can wear it. I am concerned about keeping the slot closed while in quilt mode as it could really allow a lot of air in if it is not sealed well.

Cuben is waterproof, right. So, it is also airtight. You may not be able to compress the quilt effectively if it is cuben on both sides. Also, I'm not sure about you, but when I use a vapor barrier, I have lots of condensation. Cuben is a water barrier, so you may want to test a space blanket or something cheap before you make it out of expensive fabric.

It does sound cool, though and would most certainly be light weight.

Good luck with your design.

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Cuben is waterproof, right. So, it is also airtight.

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I intend to box the edges and use ripstop on the 34" ends to let air in and allow the quilt to loft.