Can someone point out the benefits of a bivy? (Other than using them as originally intended emergency shelter/sleep systems.)
Here are a couple of issues I have with a bivy vs just using a tarp:
1. Doesn't the combined weight of a DWR bivy, such as one with a M50/M90 shell, plus a small WP (silnylon) tarp weigh *more* than the weight of a regular/large WP tarp + GC?
2. To expand on #1, isn't the weight of a shrinkwrap GC less than a bivy bottom layer, since it has to be strong enough to sew (like silnylon)?
3. Doesn't a tarp provide better/adequate ventilation so as to help reduce condensation? (Assuming it's large enough not to brush the fabric.)
4. Isn't the weight of addition high loft insulation (such as 900FP) more efficient than using a bivy to increase the effective temperature range? For example, won't 6oz of add'l 900FP down provide greater warmth than a 6oz bivy?
I looked @ all these factors and realized it makes more sense (at least for me) to:
1. take an oversized WP tarp
2. use a shrinkwrap GC
3. take a warmer quilt
The one advantage I see in using a bivy is ease of setup ie lack of setup. But, with my warmer quilt, I can throw it down cowboy style. If there is any dew, up goes the tarp. I guess the bivy would allow you to still sleep under the stars in that situation, but all the negatives seem to outweigh a few pluses.