Bivvy sack with Tarp Tents ?

[Michael Shelley]

Being new to light weight backpacking, I’m looking at loosing some weight in the shelter area.
I’m curious to know what is the prevailing thought about using a bivvy in a tarp tent shelter? I am looking into both the H.S Virga 2 and the GG Spin Shelter.
Do you need a bivvy to protect the sleeping bag from condensation in these types of shelters vs a tarp?

[kevin davidson]

With a Virga2 you don’t need a bivy to protect from condensation if your bag has decent DWR. far better is to site your tarptent in places where there is less likely to be condensation and to vent it appropriately.
If you wanted to operate in somewhat colder tempuratures, use of a bivy bag would give you perhaps another 10-15 degrees of warmth.

[Michael Shelley]

Thanks for the insight. My backpacking time is split between the Wasatch and Uintas here in Utah. So my main concern is the notorius summer thunderstorms.
Thoughts on a bag? I’m considering the Marmot Hydrogen, but have heard good things about the Helium EQ?

[kevin davidson]

Either are great bags. Light is nice, I personally use a Hydrogen bag quite a bit. Enough for most people for Summer use in the lower 48. Helium great for cold sleepers and extended use in shoulder seasons.

[John Chan]

After caving into my desire for the ultimate bivy sack (the ephemeral supply helped too) I picked up a Vapr bivy to augment my Spinnshelter. Some thoughts on the combination (after 3 nights in the wilderness).

1. For versatility you really can’t beat the Spinnshelter. You can pitch it in full lock-down mode which really cuts the amount of side-spray and bottom spray you experience in a deluge. I had to do this in Algonquin park on the weekend the tail end of Katrina came through. Otherwise, I roll up the beaks and pitch it as a high cat-tarp and don’t worry about condensation.

2. The Vapr bivy works well with the tarp but don’t forget 4 extra stakes for staking out the bivy. The bottom material is VERY slippery.

3. My only summer bag experiences are with quilts but I highly recommend them for weight savings, versatility (you can spread out the quilt for when its warm or cinch it close to your body when it gets colder), and efficiency (I had mine custom made to my proportions). Having the most breathable shell also helps control loss of loft. Mine is microlight but quantum is a better choice.

4. Dr. Jordan is correct in pointing out the extreme versatility of the bivy/quilt combination. You can sleep without drafts and at the same time thermoregulate VERY EFFECTIVELY by loosening the quilt. Really, its MUCH more comfortable than a standard mummy bag and you never worry about flattening your expensive 800+ fill down since there isn’t any under you.

5. For the price of a Marmot Hydrogen you might also want to consider a Nunatak Arc Ghost in quantum made to your exact proportions OR a Jack’sRBetter quilt that can double as a hammock underliner if you choose to go that route. Quilts are so much more versatile (IMHO).

My 2 cents FWIW,

Good luck,

John.

[Graeme Finley]

I have a HS Squall and a GG Spinnshelter, the Spinshelter being my shelter of choice for solo trips. I’ve never felt the need for a bivy using the Spinnshelter since it has provided very effective shelter from wind-blown rain and can easily be vented in a number of different ways. I have a Marmot Atom sleeping bag which has a Pertex Quantum shell so I don’t worry too much about condensation, but I’ve never actually had any significant condensation using the shelter except for one windless night at 18 degrees (using a different sleeping bag) where there were a lot of ice crystals on the inside of the shelter wall which I could just brush off.

[Michael Shelley]

Thanks John for the insight. I have been leaning twords the GG Spinshelter for the very reason you stated.
I will investigate the the idea of the quilt, it does seem to have a lot of versatility the a bag does not. Any thoughts on a Bibler winter bivy vs. the BMW vapor bivy ?

Thanks

Mike

[Michael Shelley]

Graeme, I have been going back and forth between a Montbell SS # 5 and the Marmot Atom. What are your thoughts on the Atom ? Quality etc.

Thanks

Mike

[kevin davidson]

BMW bivy is more breathable, lighter and more fully featured (zip-out mosquito net) than the winter bivy.

The Nunatak arc quilts are great but expensive and it will take a number of weeks to get one. This has not stopped me from ordering one ( a highly modified Ghost) for temps. warmer than I might use the Hydrogen for. The Hydrogen bag is availible for a considerably cheaper price if you look around–this is a good time as everyone is offering summer closeouts. Maybe the Atom, too.

[David Lewis]

If you’re sold on the Bivy idea, why not pair it with a BMW nano tarp instead? I bought a SpinnShelter specifically because it’s (essentially) weather proof so I don’t need to use a Bivy. But if I did use a Bivy, the SpinnShelter would be overkill and my shelter weight would be getting up into the range of a fully enclosed single wall tent… like the Virga/Squall. That said, the SpinnShelter / Bivy combo is more flexible than a single wall tent.

[Sunny Waller]

David..I intend to testdrive this same setup also. I received my BMW bivy 2 weeks ago and my Spinnshelter was shipped on friday. I hike in the southeast and we get lots and lots of rain. We also have some places that have very nosey skunks. The ability to “shut the door” makes a big difference in those situations.

WOW…my spinnshelter just arrived in the mail…now I can go home and play with it tonight

[Michael Shelley]

Ok here’s what i’m thinkin…
GG Spin Shelter
Marmot Atom
BMW Vapor Bivy
Thermarest Prolite 4
All said and done this system apprx 4lb
Not bad when my old tent by itself was 4.6

[kevin davidson]

why not ? make sure you’re comfortable with having a 40 degree bag–will it be versatile enough? But, BMW will soon (?) be coming out with a 11 oz. polarguard quilt which could be used as a top bag to increase the warmth of the Atom or used by itself on very warm nights. Think of it as another potential piece of a system.

[John Chan]

You can save even more weight by substituting the Prolite 4 with a Ridgerest. I use a cut-down full length Ridgerest and so long as I’m careful with campsites (pine duff or sand) there’s no problem with comfort. With an inflatable pad there’s also the possibility of air leaks at the most in-opportune times.

[Mark Verber]

Michael, as others have suggested, if you are going with a bivy, I think you would be much better off with a quilt of some sort. For the same weight as the atom a quilt would be comfortable over a wider range of temps. I haven’t used the Marmot Atom, but all the reports I have read indicate that it is comfortable to 40F for people who sleep warm. Someone I chatted with earlier this year (who thought they weren’t a particularly cold sleeper, said he wasn’t comfortable in the atom below around 50F without wearing extra clothing).

As to combining the spinshelter and the BMW vapor bivy… I think it might be overkill. The spinnshelter in a lock down pitch should not only protect you from side-blown rain, but also from wind. The only thing you would need to worry about is standing water. I have successfully weathered a number of nasty wind/rain storms in the spinnshelter, using a quilt, without a bivy. Of course, the spinnshelter in lockdown cuts you off visually and venting wise as much as a closed tent, losing some of the natural advatages of a tarp.

On the other hand, the bivy gives you a lot of options. I have mostly stopped using my bmw vapor bivy after I switched from a poncho/tarp to the spinnshelter. I have been considering selling it on ebay, but I have also been considering holding onto it because the combination of a silk liner, my quilt, and the bivy give me a very wide range of conditions where I am comfortable, and for many conditions I don’t need to setup my tarp.

–mark

[Michael Shelley]

Good insight John. Now that I’m moving away from a shelter with a built in floor I need to be more conscious of the problems with inflatable pads. What size do you cut the Ridgerest down to?

[Michael Shelley]

Thanks for the comments Mark. I’m taking a serious look into the quilt idea vs the traditional bag. Looking into the Nunatak arc series. your thoughts ?
As far as using the bivy with the Spin Shelter, I agree it could be overkill. I do like the idea of having both though so I can have the option of just using the bivy if the weather / camp location permits / requires. More options with a small weight penalty.

–Mike

[Verndal Lee]

There’s been several comments about using the Nunatak Arc series as a quilt. Why not simply choose their Back Country Blanket instead? Same concept of having all the down over you, instead of under you. Plus you have the alternative of fastening the blanket together (velcro) and converting it to a more traditional sleeping bag.

[John Chan]

I’m 67″ so I cut the Ridgerest down to 68″ and trim the sides to resemble a mummy shape. There are flat criss-cross sections on the pad that are great for trimming guide-lines.

After all is said and done, my “full length” pad is 9 oz. A regular Prolite 3 is 20 oz so you save 11 oz (almost 3/4 lb) which would bring your sleep system down to 3 lb 5 oz. Of course, you might need more material.

Now that the ball is rolling I can’t stress enough how much more versatile a quilt is. Nunatak makes great quilts with full footboxes but JacksRBetter makes backcountry quilts that can be used for hammock underpads. That level of versatility simply isn’t built into a traditional mummy.

Yes, its expensive but considering that it will probably be the last 3 season bag you buy……

[John Chan]

Nunatak’s backcountry blanket is another alternative although it isn’t the lightest (20 oz starting). In that category I would recommend looking at JacksRBetter quilts since its essentially the same design BUT they have adopted their quilts to work with a variety of hammock systems thus making your investment work harder on the trail.

[John Chan]

“As far as using the bivy with the Spin Shelter, I agree it could be overkill”.

Not really. The bivy weighs 6.2 oz. A gound mat will weigh at least 3-4 oz (unless you sleep on saran wrap). So the extra 2 oz buys alot of versatility and insurance in EXTRA inclement conditions.

My 2 c

[Graeme Finley]

Michael,

I like the Atom as a summer bag quite a lot. It’s well made and the Pertex Quantum shell gives you some comfort range in wet conditions. I find I’m not comfortable in it below 50F without addtional layers, but I’m a pretty cold sleeper – just my torso strangely enough.

[Graeme Finley]

My pad combination recently has been a GG Torsolite torso pad (3.7oz) plus a GG Nightlight (2oz). The two together give me effectively a full length pad – not a lot of padding under the legs but enough insulation that I feel comfortable down into the 40s.

[Mark Verber]

Michael.. I think the arc line of quilts from nunatak are nice. I have the ghost which has a smaller footbox than the others. I specially choice the ghost because I purchased it for warmer weather and wanted maxi ability to vent in hot weather. I already had a Western Mountaineering bag for winter.

If I was building a system from scratch I would also think about the JackRBetter down quilt because it is more versitle (I expecially like the slit when lets you wear it like a poncho) + a synthetic overquilt for cold weather.

John… you suggested that that the bivy is only 2oz more than a extra light pad, and buys alot of versatility.

I am not sure your point. The bivy and the pad do completely different things. The bivy protects against convenction cooling (on the sides and top). A pad provides sleeping comfort and insulation below you. Unless the temp is above 55F, I would take a pad to stay warm. A thin bit of silnylon won’t keep me warm, only dry.

[John Chan]

Mark,

I was referring to a ground cover. Like Tyvek.

A tyvek ground cover just sized for 1 person would be around 3-4 oz but the bivy (which doubles as a ground cover) weighs in at 6.2 oz.

You would need a ground pad with either option.

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