Our latest project is a bivvy bag, we aimed the challenging mark of 150g. One option to achieve this is to build a so called bug-bivvy that is completely made of bug netting. This construction obviously sacrifices almost all protection against wind and other elements. Another reason we decided against a bug-bivvy is that it is not challenging to stay below 150g. So we stayed with a classic design that offers some protection against spay and good protection against wind and water form below.

The Fabrics

In order to stay light we purchased the lightest fabrics we could find and ended up at [RipstopByTheRoll]{https://ripstopbytheroll.com/}.

  • The upper part is from [0.66 oz MEMBRANE 10 taffeta nylon]{https://ripstopbytheroll.com/products/0-66-oz-membrane-10-taffeta-nylon-1}
  • The floor is [MEMBRANE silpoly PU4000]{https://ripstopbytheroll.com/products/membrane-silpoly-pu4000}

When the fabrics arrived we realized for the first time what 0.66oz per square yard or in real units 22g/sqm means: it is almost nothing.

Design

As usual we designed the patters for the bivvy in Valentina and the patterns are open source at our github profile. The zipper and window are just exemplary positioned, we placed them on the cut fabric to see how things look. There is one thing we should have done: reinforcing the corners of the floor, mine broke in the first, but it is just an easy fix.

The Result

Second night in use In the picture you might see how thin the fabric is, the quilt is shining through. But at least we managed to stay below the mark of 150g with 143g. And I need to say it is pretty cozy in there, no wind, no bugs, no stones.