The problem with bed-like systems like the Zen Bivy is that they cut out draughts and are comfortable for restless sleepers, but they also increase the dead space. Practical testing at PHD Designs, as I’ve mentioned before, suggests that dead space is more costly than most realise.
I’ve been experimenting with draught reduction in quilts, using Apex prototypes in an unheated bedroom with open windows. So, minimal air movement and a slight frost.
My aim is comfort and flexibility rather than gram counting.
I’m finding that a combination of strategies is effective:
- As wide as a narrow mummy bag
- Sewn foot box almost up to the hips
- Draught flaps, as with the Ray Way quilt
- Edge tension control, as with the Nunatak quilt
I also plan to experiment with straps attached above the bottom hem leaving a tuckable edge, as with Neve Gear quilts – though this may be overkill. The main advantage would be helping to keep me on the mat.
The combined weight is trivial, and I’m finding it’s actually more efficient than my somewhat oversized mummy, because I can adjust the amount of dead space inside very precisely. Draught control is excellent.
I’d argue that this is lighter than a Zen bed, less hassle to set up, and more flexible in use. But it would be a custom job, as I’m not aware of a similar commercial offering.
.
