Lightest WP Bivy ???

[Murali C]

I was laughing as I read your comments on Tony Hobbs….yep – lots of meandering stories and way too long…….I usually skip his videos:-)

I sold my eVent recently on reddit – try reddit with a WTB – someone may sell it.

[Murali C]

There is milesgear.com pico bivy – it is listed as 19 oz. Without the pole and using some DCF bag to store this, the weight may be in the 16.5 oz range.

There is also Rab alpine bivi – seems to have great breathability numbers….one review talks about not havving too much leg space…

[Monte Masterson]

Sectionhiker did a review on the Montbell Breeze Dry-Tec some years ago and Philip explains why it really is a bivy sack. It might be described as a “sleeping bag cover” but the way the Dry-Tec completely covers the head like a mummy bag with draw string closure, it’s a bivy…..unless you’re a purest who believes only a hooped bivy with breathing space above (to at least keep the WPD material off of your upper body) counts as a bivy. https://sectionhiker.com/montbell-breeze-dry-tec-ultralight-sleeping-bag-cover/

I can’t say how the Breeze Dry-Tec compares to EVent in terms of breathability, but I’ve been out in it in steady rains with a 50* synthetic quilt and torso length NeoAir inside and the condensation isn’t that bad .The Long/Wide version is the way to go, however it’s $50 more. At least go with the Wide though and not the regular size.

I’ve also used the Dry-Tec with 40* and 30* down bags, but not in rains. A 20* Alpinlite will fit, however then a pad won’t fit inside. With synthetic bag/quilt I think the Montbell would work fine in rains at any temperatures. Below freezing down is fine using the Dry-Tec, and it wouldn’t be too bad in the rain, but down of course wouldn’t be as optimum as synthetic.

It’s easy to fashion something over the head and torso with a little ingenuity and practice. Here’s a 2.2 oz rain kilt/mini tarp I set up over the Dry Tec head and upper torso section. No extra weight because I’m packing a kilt anyway. Then it’s just the 8.3 oz “sleeping bag cover” and the weight of 6 ti Shepherd hooks and a half ounce of spectra cord. I don’t like lugging a boat anchor along in my pack all day. If you want lighter this is it. But for winter I could see a Lightwave Stormchaser bivy. https://www.lightwave.uk.com/product/shop/stormchaser

 

[Monte Masterson]

And if bugs are a concern I can add the 4,5 oz all net (net floor) bug bivy with top-zip entry. Then combined weight for Dry-Tec, stakes, lines and net is all around 14 oz. What’s more if it’s warmer out and not raining I don’t have to be inside my WPB bivy for bug protection. The system provides far more comfort and freedom than with a WPB bivy with some bug netting at the head end. Just involves a bit more fiddle factor.

You’re probably thinking “but Monte, that weighs almost as much as some tents”. Yes, however remember that you will be packing a 3 to 5 oz lighter bag/quilt because the WPB Dry-Tec adds 5 to 10 degrees warmth. Also the bivy is totally bomber when things get rough. Not so with thin ultralight tents.

[dirtbag]

Agreed about Hobbs.. lol. Ok then.. MSR Pro Bivy?

[Daniel c]

‘full anger’ ie rain or as a stand alone bivi

[Murali C]

Thanks Monte…I may just consider this now….so, here is one more review:

https://backpackinglight.com/forums/topic/3531/

[Monte Masterson]

The Yamagear Bug Canopy is an even lighter bug protection option with a bivy (one with no bug screen) at 2.4 oz. https://yamamountaingear.com/collections/in-stock-products/products/bug-canopy

 

[DWR D]

MSR Pro Bivy?

Looking at the specs a couple of thing concern me about this bivy:

1) spec for the top fabric is, “20D ripstop nylon 2 ply breathable 1000mm”… er, I don’t consider 1000mm to be water proof in a hard rain…. a mist maybe?

2) And this, “the Pro Bivy features weatherproof, breathable fabric that reduces condensation, and Xtreme Shield™ waterproof coating… Xtreme Shield™ Protection: MSR’s durable waterproof coating lasts up to 3 times longer than standard coatings.

I don’t understand the ‘waterproof coating’… is this a DWR like on jackets that needs to be kept clean and re-applied periodically?

I also don’t see a width spec; only length… so hard to know if I can fit my air mattress and 10F bag inside or not… anyone here have one of these and know what fits inside?

thanks,

DWR

[Chris K]

I have one. The width is 36″ laid flat.

The most I fit was a long wide Tensor and a WM Antelope. (I may have also snuck a thin foam pad under there as well but I can’t remember.) The bag lofted fine, but the long wide pad at 3″ deep didn’t allow for the bivy hood to come up and over enough, in my opinion. Maybe a regular wide pad would allow for this, certainly anything smaller. The girth feels more than adequate and I doubt the design is intended to contain so much bedding. That said, the hood doesn’t overlap much to begin with. The few nights I spent in this bivy were winter overnights below freezing so I haven’t experienced what it’s like in the rain.

Ryan Jordan uses this bivy, I believe mostly in winter as well. He could offer a more experienced opinion.

To your other point about waterproofness. 1,000 HH seems equivalent to sil-PU HH ratings of Big Agnes and Nemo tents, for example, at 1,200 HH. Maybe not great but not terrible either. Not sure if this bivy is really designed for all-night downpours.

Here’s a good review of the bivy.

[DWR D]

Chris… thanks for your comments…

Can you tell me, when you used this bivy on cold winter nights, how was the condensation? You used a down bag, I assume?

thanks

DWR

[Chris K]

Down bag, some condensation.

I’m new to bivys, buying both the MSR and a Katabatic Bristlecone over the last two years. In my limited experience they both get condensation. As others have mentioned over the years here, the window for a condensation-free night is pretty narrow. But I mostly do overnights using a bivy, so its pretty low risk and not a big deal to manage.

[DWR D]

https://www.gearassistant.com/what-is-hydrostatic-head/

“A good hydrostatic head for tents starts at around 3,000 mm and then goes up from there. A good hydrostatic head for waterproof jackets is 10,000 mm and a great HH rating would be 30,000 mm.”

“HH Ratings for Tents
1,000 mm – This is the minimum hydrostatic head required to keep you dry in a rain shower. This would be ok in dry conditions for things like desert camping but might not be too solid in a rainstorm.
2,000 mm – Can withstand fairly heavy rain for a few hours before showing signs of weakness.
3,000 mm – Around the industry average and waterproof enough to keep you dry in sustained rainfall.
4,000 mm – Can be trusted no matter how hard it is raining, no water is getting through this without force.”

So, yes, if you are dependent on a bivy with 1,000 HH as your only weather protection, you would be in trouble if out in anything more than a light sprinkle for very long. I would also think that the the rating goes down with age and use…

anyone with other thoughts???

DWR

[Roger Caffin]

I started testing and using coated synthetic fabrics in the late 70s.
My understanding is that the real origin of the 1,000 mm figure was actually what could be achieved with the very early acrylic coatings of any reasonably light weight. That was what was available, so that was what you got, and industry said it was enough.
Yeah, right.

Cheers

[Chris K]

Just order an MLD Event Soul!

[Kyler B]

Your gonna get condensation in a bivy in winter temperatures. Unless of coarse you actually get it in your bag. At a certain temperature the water vapour from your body will condensate. Any material that holds back the vapour or creates a temperature differential will capture condensation.

for instance, during the summer in my normal hiking area we get hot temperatures during the day and it eventually freezes up high during the night. As the temperature decreases the point at witch the air condensates water vapour seems to move closer to your body. It might be on the walls of your tent or in the down of your sleeping bag. Always happens in my winter bag.

you can see this happening when air travels up the mountains during the day and forms clouds at a certain elevation (where the air cools and condenses the water vapour).

Sometimes it creates condensation before it even gets to the breathable fabric. Any fabric that stops or slows airflow seems to create a temperature differential and builds condensation. As the windows in your car do. I have had the most breathable non waterproof fabrics do this.

Now this is better than losing your shelter and getting rain directly on your bag I agree with that. I don’t think you will be sleeping much in this type of weather event. So the only Purpose of the bivy I can see is to keep your insulation dry if you need it to last the night and not get hypothermia.

so again if I was going with a waterproof bivy I would go as cheap and lightweight as I could and plan to not use it on a nightly basis. Better off without it 99% of the time.

Save your money for a wind worthy pyramid tarp. Don’t make my mistakes haha

[DWR D]

“so again if I was going with a waterproof bivy I would go as cheap and lightweight as I could and plan to not use it on a nightly basis. Better off without it 99% of the time.”

My thoughts and experience are the opposite. I have been using bivy bags for several decades now. Condensation has not been a big problem for me. But where you use it makes a difference: areas of low humidity being better… and how you use it makes a difference: make sure your breath is directed outside the bivy… and some people just sweat more than others…  ‘cheap and lightweight as possible’ likely means it will leak in a rain… something I do  not want. And I do like to use the bivy most all the time when I go on a trip with it. Easy to set up… adds warmth the the bag… and love the stars :)))

Having read all the response to my ask for the lightest weight, rain-proof bivies, it seems to me that the  MLD Soul bivy so far is the best choice… rain-proof and the zipper down the side allow to open it up more than most to reduce condensation when it is not raining…

But please keep the suggestions coming.

[dirtbag]

if I was you. I would order the MLD eVent Sould bivy already.. as you already know.. it takes a few- to several weeks before you will even get it. If you find something better or if when you do get the MLD bivy, you dont like it or it does not perform as expected or it does not fit you well.. you could always sell it and get most, if not close to what you paid for it. Wasting time now searching for the Unicorn Bivy and you could have had the process in motion by already….

[DWR D]

Dirtbag… buy now!? hey, not so fast… you anxious to lock in your commission with Ron??? :)))

No… The lead time is too long for my pending backpack. After that, won’t need it until next spring/summer. So… no need to rush… but would still like to hear other wp bivy suggestions..

 

[dirtbag]

Lol @ commission with Ron. Hahaaa.

So basically for your trip the MLD bivy is OUT. Gotcha on that. You could post on Gear Swap: WTB MLD eVent Soul Bivy….

No commission @Dirtbag

[Murali C]

Here is a an article from MSR regarding HH numbers – where they argue – higher is not always better. Interesting article.

https://www.msrgear.com/blog/tent-fabrics-part-2-waterproof-ratings/

[Roger Caffin]

There’s a lot of deceptive marketing spin in that MSR article.
In fact, the more coating you add, the heavier and more rigid the fabric becomes, and—after a point—the more susceptible to tearing. Rainfly fabric, especially lighter weight fabric, shouldn’t be made too rigid with waterproof coating as the fabric must withstand dynamic and sustained forces such as wind gusts and being guy-lined out.

The idea that the fabric can become ‘too rigid’ is where I take exception. This does apply if the coating is PU. Yachting jackets are an example of this. That coating will weaken the fabric at almost any weight.

On the other hand, I have yet to see a silnylon fabric with too much coating. It just does not seem to happen: there is zero commercial incentive for it. Chuckle: I guess someone will now send me a sample disproving that. Let’s see.

Marketing goals . . .

Cheers

[DWR D]

That MSR article really does not say much of anything. They explain what the mm/head number are, but nowhere do they equate that to an actual hard, pounding rain… nor do they provide any logic that justifies their  1,200 mmH20 rating for that tent they mention… Basically, they are saying ‘trust us’ / ‘trust our judgement” … Unfortunately, much of the judgement these days is based on marketing … they well understand that light weight gear sells better to a certain portion of the market and they can justify higher margins for that light weight number… but… typically, if you read the actual labels on the products, they hedge away from the word ‘waterproof’ in favor of a hedge of something like ‘water resistant’… Buyer Be Ware !!!

[Murali C]

But what about the umbrella example? I am not sure if an umbrella will wet through or mist in conitnuous hard rain? ????

[DWR D]

As far as I am concerned umbrellas are irrelevant…

Umbrellas are city gear… if they fail, you can dash into a building… umbrellas are not survival gear…

And… it looks like the only reason they even brought up umbrellas was to give an example of how overhead fabrics are less vulnerable to abrasion than fabrics that are on the ground… basically, irrelevant to what HH/mm it takes to get through a intense  pounding rain without leakage…

 

 

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