[pct-l] Tents vrs Tarps - Bivies?

[Ron Moak]

Timothy,

>> You make great gear.  Would you recommend a light weight bivy (such as
the
MLD light soul -sorry, I know it's a competitor) or an epic/e-vent fabric
shell on the bag itself under the tarp?  If either. <<

Thanks for the complement. I should state up front that personally I'm not
all that fond of bivies. So you can use that bias to judge wither my
comments apply to your setup.

For those not familiar with bivies we must first clarify them. There are two
classes of bivy sacks, the "All Weather" bivy and the "Light Bivy". The All
Weather bivy is supposed to fully function on its own under most conditions.
While this class of bivies is still used by mountaineers, they have fallen
out of favor with backpackers.

The "Light Bivy" came about a number of years ago to provide enhanced
protection for your sleeping bag. It found favor with ultralight hikers who
liked to carry small tarps. These bivies are designed to perform 4 basic
functions; keep side spray off your sleeping bag, act as a ground cloth,
provide bug protection and block the wind. Let's look at each of these
functions. 

1) Enhanced water resistance - This is kind of a double edged sword issue.
Most really good sleeping bags come with excellent water resistance fabrics.
In fact I'd state that in most cases the fabric used in the sleeping bags is
better than that used in bivies. Here's a simple test to see how good you
sleeping bag is at resisting moisture. Layout your sleeping bag, create a
small depression in the shell, pour in a cup of water, then go watch a TV
show. When you dump the water, your shell should be dry to the touch and not
wetted out. If your bag passes this test, your good to go. 

I have a both a sleeping bag and quilt. One with an Epic shell the other
with a Quantum shell. Since I mostly cowboy camp, I've woken up numerous
times with my bag literally covered with thousands of small dew drops. With
both bags, I can just get up and shake off the dew and stuff the bag. I
would recommend sleeping under natural cover, if available. It'll eliminate
most of the potential of dew formation.

The downside for using bivies to keep outside condensation off your bag is
that many of them will form condensation inside of the bivy sack. As you
sleep, warm moisture will work its way through your bag. Upon escaping its
shell it will condense on the underside of the colder bivy. This kind of
negates the whole purpose of the bivy.

Also, a larger tarp that provides better rain protection you can eliminate
the need for the bivy. Three ounces of additional tarp weight can eliminate
the need for an eight ounce bivy.

2) Function as a ground cloth - It's true that they can eliminate the need
for a ground cloth. But personally, I want a ground cloth larger than my
sleeping bag. I like to keep other items of gear on my ground cloth to keep
them off the muddy ground. You can get a pretty good and cheap ground cloth
made out of painter plastic that weighs a couple of ounces.

3) Provide bug protection - Yes, bivies will keep the creepy crawlies and
the mosquitoes at bay. However most bivies have minimal netting. Mosquitoes
will still buzz your ears and it's often difficult to keep the netting off
your face, where you're still subject to mosquito bites. 

For heavy bug season, I prefer a bug tent. There are a number available
today that weight no more than a bivy and allow you to at least sit up in a
bug free world.

4) Wind Block - With the move from sleeping bags to quilts, bivies have
increased in popularity. Anyone who's slept in a quilt, soon learns that
even a slight movement can sometime bring an unwanted wafting of cold air.
So bivies can serve to block these unwanted incursions and give you a more
gentle sleep. 

I think the problem isn't with the quilt per say. It's with the size of the
quilt. When we downsized our tarps to save weight, we downsized it too much
so we needed a bivy. The same hold true with quilts. I think it's better to
get an oversized quilt that will move with you than to try and fix the
problem with a bivy.

Many people have opted to get quilts with sheer bottom panel of fabric to
provide a wind block. This will work, however it too has its drawbacks. On
hot nights you need to be able to regulate your temperature. Sleeping in a
full enclosed tube, it's impossible to pop open a side or toss out a leg to
let in some cooler air. In addition most bivy sacks are sized to be just
slightly larger than you sleeping bag. With the minimal space, it's
difficult to adjust your sleeping bag to cool down.

Bottom line; for me bivies are too often used as a patch to cover a more
structural problem with your gear selection. It's better to think through
the needs of all your gear than to buy another piece of gear to fill in the
holes. In the end, you'll save weight, money and have a better camp setup.

File this one in the "For What It's Worth" bin. Hopefully it's food for
thought.

Happy hiking!

-----------------------------
Fallingwater