Hi Robert, Lets play "Design an Alphamid Tarp.
1. Big enough but no bigger than necessary.
2. Very light, 7.5 ounce range, or less which should be light enough to get the attention of all us gram counters.
3. Cost not a big problem but if a material that is cheaper than Cuben can be used go for it.
What do we think we know about the Alphamid Nano Tarp:
4. Made by Oware and modeled after their small Alphamid Tarp.
5. Oware's small size is 4.5' x 9' x 5.5'.
6. Alphamid Nano Tarp color seems to be gray to transparent. Cuben/Nano material is transparent and the gray looking color could be from the background.
7. Size based on Roberts windscreen baseline idea seems to be just over 7' long and 4.5' high. Robert believes the tarp is not rectangular. I think the tarp is rectangular but maybe staked out in a way to distort the shape for a bit more room or to lift the edges to help vent the tarp when the front is closed.
Going with another size (3' x 7' and 4.5' high) I come up with about 5.63 sq yards of material to make the Alphamid Tarp. Again this does not add material for seams etc and someone can re-check my math.
A 3' x 7' footprint is big enough for me and is the same size as the small winter tent I made a few years ago. My tent was 5' high but 4' would have been high enough to sit-up in.
Using Cuben fiber and making the tarp this smaller size, 5.63 sq yards, and using the 0.35 to 0.44 oz a sq yard product, the finished weight could be in the
(sit down) 3oz range (+/-) 0.5oz. The Cuben material at about $17 a yard would come out to $102 plus change. Add to this guy lines, stakes etc.
My next thought is I wonder how one of these would work on an AT Thru-Hike. It sure would be light and also be more private than a regular tarp.
Even made out of some of the very cheap spinnaker material available this size might still weigh less than 7.5oz.