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Edited by daniel@fishfamilypdx.com on 06/12/2013 08:23:16 MDT.

Still not ready to MYOG. Sorry, but it's not the route I want to take. I appreciate the advice.

Not looking at the Frog Togs either. I'm also pretty sure what kind of setup I'm looking for, and it's Bivy + Tarp.

About bugs, some of the worst nights I've had with skeeters have been during rainstorms. They flock to a tarp and hang out. I'm not risking a headnet, I'm going for full mosquito coverage.

Thanks for the continuing information. I'm in the process of working through the posts.

If you're getting a full size TS, I agree with others that there's basically zero reason for a WPB bivy. Any non-WPB fabric will be far more breathable than the most breathable WPB, even Event. M90 from Borah gear is 80 bucks and you could get it made however you want.

" Any non-WPB fabric will be far more breathable than the most breathable WPB, even Event. "

While that's a true statement, that doesn't mean a more breathable fabric is better for use in a bivy when condensation is of concern.

This is a very good article,and so is this one.

~"Vapor permeable fabrics have membranes that absorbs water like paper. The water once in the membrane works its way to the outside where it again turns to vapore and is carried off. Air however will not flow through it. Most WPB fabrics that use polyurethane membrane are only Vapor breathable and they typically don't breath much until interior humidity gets high. Breathability specs for polyurethane WPB fabrics are typically well below Event. Also you won't see a CFM rating for polyurethane WPB fabrics simply because air won't flow through the membrane. Pertex Shield is an example of this type of fabric. I don't think vapor permeable Membrane fabrics are a good choice for bivy's

Air permeable fabrics like event have very small holes that allow air and vapor through but don't allow or make it very hard for liquid water to get through. Event has a hydrostatic head of about 25,000mm and a CFM rating of 0.5 (If I remember correctly). If you increase the breathability (higher CFM)the hydrostatic head goes down. So when you get to ordinary fabric such as Momentum 50 your hydrostatic head goes to almost zero and the CFM ratting goes very high."


Read this, it's on Page 3.

" Any non-WPB fabric will be far more breathable than the most breathable WPB, even Event. "

Yes but not in the conditions that you think with respect to eVent (as described earlier). As your body temperature goes up, the temp differential as presented as moisture is pushed through the bivy and condenses on top of the fabric. With eVent, that is a minor inconvenience. You wipe it off or it rolls off but you remain dry. With a non-WPB fabric, the fabric then wets out and gets you soaked.

I have used many bivvies over the years, including several eVent bivvies including the Integral Designs eVent overbag. With that bivy, I have never once, and I mean never, had internal condensation in temperatures ranging from 50F to -10F, in the snow, desert, and by water sources. I have been soaked in a bivy made of momentum fabric (MLD) and had condensation on the floor (70d pu coated) of an eVent bivy but never in that overbag.

Highly recommend reading some of the BPL articles on the subject and as well, reviews of specific eVent bivvies and clothing available on this site.

Going outside the box a little how about the TT Notch inner nettent that has partially solid sides?:

Edited by hes on 03/06/2013 12:39:12 MST.

The advantages with eVent bivys that I've read of seems to typically be below freezing (haven't used a WPB bivy myself, though I've made a few out of various DWR fabrics). If a primary you're wanting it is for mosquitos, I'm assuming it isn't for that cold of conditions. Some kind of nest or innernet seems a lot more appropriate than a bivy for what you say you want to use it for. A trailstar provides some serious coverage. Even though it doesn't pitch completely to the ground, you aren't going to get wet from blowing rain. Snow, maybe, in which case it might be cold enough that a synthetic overquilt would be more appropriate than a bivy anyway for moisture management and bugs probably aren't an issue.

People seem to be misinterpreting my purpose. You recommend something for one condition and then ignore a second condition. I need this bivy to do MULTIPLE things well, not just one scenario. It's not relevant if there are no bugs in the winter, my bivy needs to be bugproof.

A) As with anything, I'm not made of money. if I buy one system that works in three potential conditions, I'm way ahead than buying for just one condition.

B) I know that spindrift and wind are an issue under a tarp. Some people keep repeating "Just tie down your tarp tight!" but it's not quite that simple. A lot of terrain won't allow a "waterproof" tarp pitch. The bivy bag is my second layer of protection.

C) Redundancy in a shelter is useful if you're taking it for storms. If I can't get my tarp to pitch or if the conditions are too rough for it, and I have a bivy, I may just save my life.


So, Thank you for the tent suggestions and the advice, but I am still JUST looking for what's in the OP.

Thanks,
M

In fairness, nobody can read your mind. You seem to add requirements all the time that aren't in your original post. Moreover, if "price is no consideration" as said in OP, then having multiple setups should be an option. Just sayin.

Also, if you're now thinking of taking this setup into winter storms you might want to check on that. Trailstar is great in wind but I'm not so sure about snow. . .

Edited by hes on 03/06/2013 13:08:53 MST.

So will you be selling your hammock system since it doesn't cover all scenarios you might encounter?

Yeah, I mean, I didn't say anything about snow. I just feel like if you make a Bivy thread and someone reccomends a Notch, it's off-track. My OP is pretty clear. I'm getting two conflicting points of view; some people say eVent has the least condensation, and some people say Water Resistant materials are the most breathable. Nobody can back that up with anything other than opinion, which I already have in spades.

Maybe it's an unanswerable question. I feel like if I ask which down jacket is the warmest, someone has a chart with actual quantitative data, but ask about a bivy... and you get a whole spectrum of ideas, advice, chastising, etc.

I don't think I've added a single thing to the OP... Storms, blocking wind/rain under the tarp, breathable, bugproof. Not everyone is off-track but some people are.

Money is no object since the ceiling for a bivy is like $400. I'm happy to pay for a good bivy. What I can't do is spend $2000 on a multiple shelter system. Plus, on longer trips I need one setup to cover the spectrum.


I mean it when I say I appreciate the off-track stuff, I just need the on-track stuff more.


And no, I'm not selling my hammock. OP says, can't always use a hammock!

Edited by mdilthey on 03/06/2013 13:18:41 MST.

Max,
I can back up my very rare condensation claims with over 100 bivys in use.
Buy and Uber Bivy and take it out for a night in a nasty storm.
You will sleep warm and dry. If not, send it back, and I'll refund your money.
Sounds like a common sense approach to solve the question :)

Max,

I'd definitely take David up on that offer. How can you beat that?

No bivy will do what you are wanting very well in this range of situations.

This might suck the least at accomplishing the things you want:

http://www.exped.com/exped/web/exped_homepage_int.nsf/0/77CDB11B04309DC6C1256F2B002E724D?opendocument

I couldn't find one for sale. mountainequipment.com has one with PU floor. Maybe MLD will make one to your specs. Either will likely be more expensive than 2 separate specialized products.

Actually, that offer extends to everyone. As long as you use the groundsheet and don't drag it through the woods, there will be no wear on the bivy. I've got over 25 nights in mine, with no detectable wear. I'm that confident that this bivy is a game changer. I love sleeping in storms :)

David,

The uber looks great and I'm tempted by the double as it seems my daughter might join me on the wonderland this summer. Is it possible to add a tie point to use in lieu of a hoop and if so, how much weight would I save by forgoing the loop?

Edit: What are the packed dimensions of the Double uber? I may have overlooked it but I didn't see that on your website.
Edit edit: If it was a snake it would have bit me. 6" x 18"

Edited by IDBLOOM on 03/06/2013 13:49:33 MST.

The conflict isn't the POVs...its your interpretaion. Breathability isn't the only determining factor for wetness inside bivy. If you use a goretex bivy in a thunderstorm (no tarp) it will fair much better than one made of m50.
I've had copious condensation on a net tent inner

Event is less breathable than typical wrb by an order of maginitude in most cases.

David Ure has posted multiple times that he doesn't get wet in Event..many others have posted the same elsewhere. You don't have to look hard for people saying wrb condesation happened.

There aren't CFM numbers for everything, but for quite a few.

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=45026&disable_pagination=1

edit: Why don't you just buy the trailstar, take it out in a gnarly storm in the yard or on an overnight, and figure out what your needs actually are rather than theorizing on the interwebs without having used any part of the perfect system you're trying to put together.

Edited by brendans on 03/06/2013 14:02:25 MST.