Crux B1 Scout bivi-bag

Waterproof & Breathable X-tex fabric / Non Hoop
Weighs 386g (excluding bag)
Code: SS16112
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A glorified sleeping bag cover, the B1 Scout is as simple as a bivi bag gets. It has a drawcord around the face, but you can never completely seal the face area and there is no mesh insect screen. The design may be plain, but the B1 Scout's X-tex fabric is decidedly hi-tech.

Crux says:

X-tex fabric has a woven textile face with a coating to make it both waterproof and breathable, with a 50 denier polyester face. 50 denier is a heavy yarn by today's standards, but we consider it important for a mountaineering tent, since the intrinsic strength of fabric is derived primarily from the thickness of the yarn. Unusually we have chosen polyester rather than nylon, as polyester offers superior resistance to UV degradation.

In 2015 Crux introduced it's B1 range of bivi bags: the Scout, the Recce and the Patrol. The B1 Scout is the simplest and lightest in the range, with a drawcord closure that leaves a small area of the face uncovered. The robust B1 Recce can be completely closed over the face. The B1 Patrol is the largest and most sophisticated of the Crux bivi bags, with a stiffened wire-rimmed hood that provides shelter while remaining open.

What sets the B1 range apart is it's X-tex fabric - the same revolutionary fabric used in Crux's X1 series of single wall bivouac tents. Most bivi bags use a fabric with a microporous membrane or coating. These rely on differences in the partial pressure of humidity in the air in order to breathe. They only work however, when the humidity is in the vapour state: once condensation has occurred they cease to breathe. X-tex fabric is different: by combining a PU coating with activated carbon, it is able to absorb water even in the liquid state and still continue to breathe.

- Reviewed by Ultralight Outdoor Gear

  • Simple lightweight design
  • Small pack size
  • Waterproof/Breathable T-tex fabric
  • Weight: 386g + 10g stuff sack
  • Hydrostatic head: 20,000mm
  • MVTR: 25,000g/m2/24hrs
  • Inside length: 204cm
  • Width at shoulders: 68cm
  • Width at footbox: 49cm
Showing our 2 Crux B1 Scout bivi-bag reviews with an average rating of Very Good. Would you like to write a review?
Review Summary - 4 out of 5 based on 2 ratings.
September 27, 2017 | Simon Miles

This is a light but tough bivi-bag, well made, and totally waterproof. However, in my experience breathability is poor. I used it overnight, under a tarp, in only moderately cool/humid conditions (no rain). There was significant condensation inside the bag by morning, and my sleeping bag was quite damp. I appreciate the B1 is cheaper than more sophisticated Gore-Tex bags, but it really didn't breathe any better than a more basic bivi costing half as much.

Ultralight Outdoor Gear Limited
July 24, 2017 | Ian Woolley
Excellent option for a high-spec bivi

I took the Crux B1 Scout on a three-night bivi trip in the Cairngorms in July. For me the three essential aspects of a bivi are that it is waterproof, breathable (no condensation) and lightweight. The B1 Scout ticks all three boxes admirably.
There is a high-quality, durable feel to the product, and the specs are comparable to Goretex / eVent (and a fair bit cheaper). The X-tec fabric is on the top half of the bag; on the underside is a thicker waterproof sheet. The issue with this is you'll want to roll on to your side when it's raining so your face doesn't get wet, but even doing so I didn't have an issue with breathability (an alternative option is to go for the poled B1 Patrol, though that's twice the weight!). Having spent one night in heavy rain, I can confirm it is perfectly waterproof. Condensation wasn't an issue for me even though I was using a thick 4-season sleeping bag. That is a major improvement on the basic budget bivi bags out there, and particularly valuable if you're considering multiple days out in the elements.
Overall I'd say if you are only planning on bivying for one night the budget bivi bags will do the job, but for multi-day trips or for those looking for a top-end, high-spec bag, the B1 Scout is an excellent option, and a fair way cheaper than its peers.

Ultralight Outdoor Gear Limited