ultralight bivies.

[John Chan]

Has anyone tried the new Breeze Dry-Tec Montbell ultra-light bivy sac?

I’m considering it as an alternative to the BMW bivy… they are essentially the same weight but the Montbell is waterproof/breathable.

TIA.

[Anonymous]

I don’t pretend to be an expert on this product, but like you John was intrigued with the Montbell Breeze Dry-Tec Bivy. The following is an excerpt from a recent email I had with the Montbell customer service:

Thank you for contacting MontBell. Breeze Dry-Tec (BDT) is a new waterproof/breathable material offered exclusively by MontBell. Developed to be exceptionally breathable, BDT is actually an air permeable fabric making it highly breathable. Comparing these four materials is not really possible, Gore-Tex and BDT are waterproof/breathable materials. Pertex makes several versions that are considered to be highly water resistant, and Epic is a treatment that also provides highly water resistant performance. So, it’s really two different categories, waterproof/breathable and water resistant. Both categories have excellent performance when used in the intended conditions.
Gore-Tex is widely excepted as one of the best and most consistent waterproof/breathable materials and provides many different waterproof/breathable materials. MontBell uses a wide range of Gore-Tex products with excellent results. With the marketplace constantly evolving, MontBell is also constantly working to offer new and innovative products and materials. Breeze Dry-Tec represents one step in the development, this material also allows MontBell to create high quality products at a very reasonable cost to our customers. (Watch for a winter hard shell to come out this fall made with BDT!) We have had excellent response to the Peak Shell so far and it is selling very well! So much that we expect to sell out before the Fall & Winter Shipment arrives (Sept/Oct).

Hope that this was helpful.

[paul johnson]

Post deleted.

[Anonymous]

https://www2.montbell.com/america/asp/products/Spg_shosai.asp?cat=1106&hinban=2321027

Montbell Breeze Dry-Tec™ U.L. Sleeping Bag Cover
Our popular and proven Ultra Light Sleeping Bag Cover made from a 2-layer version of our new Breeze Dry-Tec™ means similar weight and performance at a more affordable price.

• Fully seam taped
• 2-layer Breeze Dry-Tec™ construction
• Air-permeable water-proof breathable material
• 12-denier micro rip-stop nylon shell
• Max Dimension 88.6″ x 33.1″

[Color] BASM (Balsam)

[Weight] 6.3 oz.
[Stuffed Size] 3.5″ x 2″ x 7″

[Anonymous]

Price: $ 110.00

[Sunny Waller]

NUTS…don’t temp me. I so want a BMW bivy and poncho but I have had no luck getting them. They are still out of stock and I have been unable to find out when either one may become available. I had intended to use the bivy/poncho as my primary rig this fall and winter but unfortunatly may have to make other plans. I think I will stick it out though because I know the BMW is an excellent product that has really been field tested. I know the floor is waterproof..and HEY it looks good on TV (travel channel) The Montbell Bivy is really a sleeping bag cover..it does not say that the floor is reinforced so it may also require the use of a ground cloth and it makes no mention of bug mesh and you gotta have bug mesh in my neck of the woods.

[John Chan]

I considered the BMW and Oware bivies but I’m not sure if that’s the best option for me.
The reason I say this is because both ARE true bivies with zip-out noseeum and head peaks. This means that unless you are willing to sleep with your head outside the bivy you will to some extent be breathing into the bivy which can result in excess condensation. I like the Montbell sleeping bag sacs because you can cinch up the sac around your head and avoid this problem.

Insects?

I plan on getting some Nano-noseeum from thru-hiker and jury-rigging a minimal/ dedicated headnet (facenet) that can be used with the Montbell which should weigh less than 1.5 oz and be less condensation prone than a “true bivy” option. Really, I’m getting the bivy sac for the cooler nights when you feel the draft under your quilt.

[Jon Solomon]

I’ve tried both versions of the Mont Bell UL Bivy (really just a bag cover): the 2-layer Gore Tex version and the new Breeze Dry Tec version. The BDT version is slighly lighter and less expensive, and, as far as my experience goes, better than the Gore Tex. Don’t bother with the Gore Tex version! The BDT does not seem to be as breathable as the eVENT bivy by Exped that I have tried, but it is definitely better than the 2-layer Gore Tex. For just a little over six ounces, it offers a lot of protection. I’ve taken to carrying it sometimes just for the emergency value.

I don’t know however if it would really be an “alternative” to the BMW bivy. It really depends on what the rest of your shelter/sleep system is like and what conditions you expect. Each offers different features, including breathability, water resistance, bug protection, and ground protection; I’m sure you’ve thought about it.

While I was hiking in Japan this summer, where you are sometimes kind of forced to camp on impacted ground, I was really glad to have the BMW bivy for its deep floor. I sealed the four corner floor seams, and it saved my skin one night when the campground under my Spinnshelter was flooded out. I don’t know how the MB BDT bag cover would do if it really sits in pooling water?

In short, both have their place. If price is what is stopping you, you might consider the cheaper Mountain Laurel Designs Bivy. Maybe that way you can get both kinds! Together they only weigh 12-13 ounces and give an enormous range of protection…

[Nathan Chaszeyka]

Equinox Ultralight Bivy? Has anyone used this bivy and what is your take on it if you have. The information about it is pretty limited but it looks like it could be a good option.

It has a mummy hood now and weighs 7oz.

[Marion Watts]

I have liked my Equinox bivy very much. It actually weighes out at 6.5 oz. For the price, it can’t be beat. One thing to keep in mind. If you sleep with a full pad, (like I MUST for a good nights sleep) it has to be a mummy cut pad or it fits funny.

[Doug Johnson]

Hello all-

Don’t forget the Mountain Laurel Designs products. They offer bivies and poncho tarps out of silnylon and spinnaker cloth that might suit your needs nicely. I’ve used several of their products and the quality is top-notch.

http://www.mountainlaureldesigns.com

Best of luck in your adventures!

Doug Johnson, Shelter Editor

[Sunny Waller]

Wheee!!! My BMW bivy just shipped :) I am gonna be worthless for the rest of this workday.

[Bill Fornshell]

Early this week BMW anounced that the Vapr Bivy was back in stock. I have been waiting for this and put one on order. Today I received my BMW Vapr Bivy, fast service if I do say so. From the notice it was shipped till today was about 3 days.

Mine is the Charcoal or Gunmetal? Top – Black Bottom. These are just the colors I had hoped for.

I unpacked it and got in. I ordered the Large size. Getting in and out was easier than I thought it would be. I have lots of room for my Down Air Mattress and Down Sleeping Bag.

The weight of the Large – Bivy without the Bug Net window and Stuff Sack is: 6.41oz

The weight of the Stuff Sack is 0.29oz.

The weight of the Bug Net window is 0.80oz.

[Michael Martin]

I just received the new Montbell Catalog in the mail and, like several posters above, noticed their 6.3oz bivy (aka “sleeping bag cover”) made of their “Breeze Dry-Tec” fabric.

I was wondering if BPL has had a chance to evaluate this fabric. Do you agree with Jon S.’s experience above? According to the catalog description, they have eliminated the PU coating on the (presumably ePTFE???) laminate and claim substantial air permeability.

The description sounded like the fabric had many of the desirable qualities of eVent. Yet, the Montbell bivy weighs under 7oz whereas eVent bivies appear to be over 18oz!

So, Ryan, Alan, et. al., what’s the verdict? Fabric breakthrough, or marketing hype?

Cheers,

-Mike

[kevin davidson]

If only Montbell would develop a decent hood w/ zip-out netting and a loop or something on the hood so it can be pulled away from the sleeper’s face—-in short, a Vapor Bivy done up in Breeze Dry-tec. Then again,Montbell does not call this a bivy—-it’s a “sleeping bag cover”.

It seems to be a very good W/B material which breathes better than any of the Gore-tex family and (reputedly) almost as well as eVENT.

[paul johnson]

looks like a very nice product. i’ve had it “bookmarked” for a some time now as a possible future purchase.

i think of it more as a simple bag cover, than a bivy. there’s no bug netting and i’m not sure how tightly you can close it up even with the drawcord. perhaps a bit arbitrary, but these are two minimal features that i think of when i think of bivy (certainly there are other more advanced bivy features – tie-downs, pad holders, hood tie-up loop, zipper(s), overhead wire or sectioned hoop/pole, rain gutters, tie-in(s) on climbing bivies, venting, etc). but again, these are just my arbitrary distinctions.

as to breathability, based upon Montbell published figures for their BDT fabric, it appears to be only ~54% as breathable as eVENT (15000 gm/sq m/24h vs 27826 gm/sq. m/24h). how this equates to “real world” performance is perhaps another matter.

[NOTE: subsequent to posting this post, Michael Martin pointed out that i’m quoting figures from two slightly different tests. please be sure to read his following post, as well as my reply to him for more info on these tests and any others which follow in this Thread. sorry, for the incorrect info – my apologies to all who read this Thread.]

have not seen published figures for waterproofness for either BDT or eVENT, so don’t know how they compare, but it seems anyone can make something waterproof, but breathable – that’s another matter.

oh…the weight and price are both very attractive. now, if only they could make it in a nice “earth tone”, or gray stealth color.

[Michael Martin]

>> as to breathability, based upon Montbell published figures for their BDT fabric, it appears to be only ~54% as breathable as eVENT (15000 gm/sq m/24h vs 27826 gm/sq. m/24h). how this equates to “real world” performance is perhaps another matter.

Thanks for the info, Paul.

Did you get your 27,826 gm/sqm/24h figure from this article?

http://www.backpackinglight.com/cgi-bin/backpackinglight/00316.html

I wonder if this may be an apples to oranges comparison. That figure for eVent is for a JIS L 1099 test (where, for example, Goretex XCR rated 21,194 gm/sqm/24h). The Montbell info I have claims 15,000 gm/sqm/24h using JIS L1099 B-2, where they further state that XCR is only at 13,500 gm/sqm/24h. I’m guessing that the tests must somehow different if you use XCR as a benchmark.

Any comments? What’s the difference between JIS L1099 and JIS L1099 B-2?

Best Regards,

-Mike

[paul johnson]

Mike,

yes. that’s the source. hadn’t noticed the diff. in tests. thanks for taking the time to reply & set me straight on this point.

this being the case, as you point out, perhaps what was prev. stated in a couple of posts is true, viz. BDT is as breathable as eVENT.

don’t know the diff b/t the two tests. this is all i’ve been able to determine about this. JIS L1099 B1 (or B-1) is listed as an inverted cup test. Note the column header test title in Mr. Dixon’s excellent BPL article you referenced, viz. “desiccant inverted cup” based upon the limited info i’ve found on the web this is a B-1 type of test. JIS L1099 A-1 is listed as an upright cup test, so we can easily understand that A-1 & B-1 would be significantly different. not sure of the difference between a B-1 and a B-2 test.

here’s a link to a Toray web page. The “B-1 Method” column head is an active link. click on it to load another page with a very good description of the B1 test.

ToraySpecTable

i can find no info on the web for a B2 or B-2 test for this JIS L1099 spec./std. – tried: Jeeves, Google, and Yahoo. i also found info which indicated that the A-1 method is a “desiccant” method and that the A-2 method is a “water” method. Perhaps the same distinction is true of the two “B” methods. if this is so, then the B-2 method you mentioned from the Montbell info is the NOT THE SAME as Mr. Dixon’s info. That is, if A-1 = desiccant and A-2 = water, and the column in Mr. Dixon’s table is labeled, in part, “desiccant”, then it prob. is the B-1 method. Montbell called theirs a B-2 method (a water method???). so, as you astutely noticed and pointed out, it appears to be an oranges-to-grapefruit (since both inverted cup methods) comparison. i sure missed that fine point. i’m going to “annotate” my prev. post, so any reading it will read your following post.

sorry i can’t be any help. maybe Alan Dixon will read this and be kind enough to reply.

[Christopher May]

If it turns out that BDT is as breathable as eVENT an option might be to buy the bivy from Montbell and then sew in (or have sewn in) a bug screen or other wanted options.

[kevin davidson]

Christopher–the hood, such as it is, would have to be recut and material added to make it a functional hood that you could add a zippable screen to.

My perspective, anyway.

[Michael Martin]

Paul-

Thanks for the tips on the various test standards. It sure does seem hard to get unbiased data on WP/B material performance. It seems nearly impossible to cut through the marketing hype — even with “objective” test data…

>> maybe Alan Dixon will read this and be kind enough to reply.

Here, Here! Alan, please help us. :)

btw, I think Alan’s article on WP/B technologies is the all-time best article on BPL — well worth the cost of a Premium Member Subscription all by itself!

Best Regards,

-Mike Martin

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