The Best Water Proof Breathable Bivy under 1 lb?

Borah Gear Snowyside eVent® Bivy fits me well with a 2.5″ thick pad inside and a 20°F quilt.

I’m broad-shouldered side sleeper with a 42.5″ chest circumference.

The bivy is way too long for me (advertised to fit 6’4″ sleepers), but I’m not complaining. Much cheaper than MLD’s, and of pretty decent quality. Its measured weight is 13.00 oz with the netting attached (12.32 oz without), and the measured length is 90″. I much prefer the durability of its non-cuben floor.

I have the “regular” MLD eVENT bivy- very well constructed, breathes well- even in less than desirable environs ie snow caves/snow trenches

mine is the Large and fits myself (6′), 0 degree quilt and xtherm pad w/o any issues

spendy, but I don’t have a single complaint about it- it’s seen a lot of outings and will see a lot more (God willing of course :))

Does the Borah Bivy breath well?

Jeff,

I own a Borah Gear (BG) Snowyside but, I have not tested the equivalent Mountain Laurel Designs (MLD) product. They both use 3 layer eVent for their tops but, different materials for their bottoms. The MLD version uses Cuben and the BG version uses silpoly of about the same weight. I tested the silpoly HH at >3,500 mm H2O after 5,200 wet flex cycles. In contrast my other silnylon bottomed bivy, from a US cottage manufacturer, only tested 1,200mm new and about 1/2 that after 5,200 wet flex cycles.

eVent bivies standard sizes are normally smaller than other material types. For example, the MLD Superlight bivy standard max girth options are 74″, 78″, and 82″ whereas for their eVent bivy, the standard max girth options are 72″ and 76″. The only standard max girth from BG is 76″.

BG will customize the dimensions if requested. I strongly suggest you error on the side of caution regarding the max girth you order. Measure the girth of your combined worst case body, sleep clothing, quilt/bag, and mattress plus a couple of inches for an air gap. Extra circumference is extra weight but, it is also extra space for a potential dead-air gap to move the dew point further away from your core.

Does the Borah Bivy breath well?

“Well” is a relative term. I find its breathability adequate for the Appalachia @ 35-40°F with relative humidity of about 60%. I am sure that if I used it out West where the humidity is generally lower, it would perform much better.

I don’t own it anymore, but I used the previous generation of Borah Bivy in the high 80s (at night) next to the Potomac on the C&O. It was pretty warm and humid, but I managed okay. So in regards to whether an eVent bivy breathes well, I think it does, assuming some concessions.

I find one has to carefully manage the micro climate within a bivy in order to work well in varied situations. You don’t want to get too warm inside the bivy, which might mean not using a sleeping bag or pad at all. For that specific night I wanted the ground to suck the heat from me.