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  1. #1
    Peter_pan's Avatar
    Join Date
    Oct 2006
    JRB 11x10 Cat Tarp
    JRB UQ of season

    Breathability Discussion

    edited by angrysparrow - I split this discussion from the Cuben Fiber thread. This discussion is good, but shouldn't hijack the topic.

    Quote Originally Posted by gnome View Post
    cuben doesn't breathe,period. However neither does a closed cell pad. and we all use them. I have spent several nights in my cuben Ham. it is fine. The tarp of mine is all taped, and holds up well, for tie outs I use a piece of gorilla tape. the cuben is sandwitched between a single piece doubled back on it self, I then put about 3 stainless ordinary staples to hold (in shear tape is very strong not so strong in peel) cheaper from the manufacturer! my H is abour .44 oz/ yd I believe, stronger than 1.5 or so syl
    Gnome, et al,

    The prevailing wisdom is that a hammock should be breathable.

    Your statemant that we all use closed cell pads is far from accurate...In fact, between Speer pea pods, snug fits, home made UQs and 1/2 UQs, Garlington type taco tubes, Dams, Dam clones, JRB WS and JRB Under Quilts (numbering in the thousands) the majority of folks probably do not use pads. Certainly those who consider themselves back sweaters have moved on from pads.

    YMMV... Glad it works for you...

    Last edited by angrysparrow; 08-18-2008 at 10:44. Reason: added note at top
    Ounces to Grams. ... Largest supplier of camping quilts and under quilts...Home of the Original Nest Under Quilt, and Bear Mountain Bridge Hammock. 800 595 0413

  2. #2
    Senior Member
    Join Date
    Dec 2007
    Doraville, GA
    I don't know about this 'prevailing wisdom' but I do know that you would like your hammock to be breathable (or at least as breathable as possible with the insulation you are using) when you are overheating and dealing with sweat, or sensible perspiration. On the other hand, I also know that you would like you hammock to not be breathable when you are dealing with trying to stay warm and are only dealing with insensible perspiration-- if you know how to deal with it.

    It is not a situation where one case is always the best choice. Wise hammockers that use a breathable hammock with breathable under side insultaion (underquilts, pea pods, etc) often add a vapor barrier between the hammock and the underside insulation to extend the low temperature range. It is like whether to use a tarp that allows air flow or one that closes off and blocks the wind. A nice cool breeze is one thing, a blast of frigid air is something else. Just like a net hammock wouldn't be a wise choice when snow camping, a non-breathable hammock wouldn't be a wise choice when camping in 85F weather. Those are extremes and in the middle range where we typically are, there are shades of gray, so to speak. You will run it to situations where one might be preferred over the other and situations where there isn't that much difference. I wish I could snap my fingers and make my hammock switch back-and-forth between being very breathable to being non-breathable. While I am wishing, it would be nice if I could wave my hand and adjust how my tarp is pitched as well.
    Youngblood AT2000

  3. #3
    Darby's Avatar
    Join Date
    Apr 2007
    Elizabeth City, North Carolina
    Switchback 1.9DL
    10x12 TTTG CatCut
    TTTG Ring Buckle
    Quote Originally Posted by Youngblood View Post
    ... While I am wishing, it would be nice if I could wave my hand and adjust how my tarp is pitched as well.
    All you need is some good old fairy dust.
    Beer won't solve problems, but then again, neither will milk !
    Designer of the Switchback Hammock
    Tree to Tree Trail Gear:

  4. #4
    slowhike's Avatar
    Join Date
    Oct 2006
    Winston-Salem, NC
    DIY, gathered end , w/ spreader
    DIY w/ pull-outs
    DAM/ HG Incubator
    Webbing and rings
    I sleep on a non breathable, insulated air mat year round. It's just as nonbreathable as a ccf pad.
    Having a layer of fabric between me & the air mat helps take care of dispersing perspiration.
    don`t leave the CREATOR out of the creation!

  5. #5
    i used a sil uq in winter on several occasions, and never experienced moisture build up. and it did make a very noticeable difference in blocking the wind, as i can sometimes feel it through a breathable uq, wheras with the sil uq i never could. i'd say in cool weather and colder, a sil or cuben hammock would perform better than a breathable version, simply because of better protection from wind and water, and would likely allow one to carry a much smaller tarp, particularly if you didn't need to protect your uq.

    stevenson's warmlite has some really good info on vapor barriers and how to use them properly for anyone who is interested.

  6. #6
    Senior Member QChan's Avatar
    Join Date
    May 2008
    Edmonton, A.B.
    Homemade asym
    Homemade blackcat
    JRB Hudson River
    It looks like a plastic tarp my dad has...

    Does this stuff breath at all?

  7. #7
    Senior Member
    Join Date
    Dec 2007
    Doraville, GA
    Quote Originally Posted by warbonnetguy View Post
    stevenson's warmlite has some really good info on vapor barriers and how to use them properly for anyone who is interested.

    I have read that a few times over the years. Jack Stevenson has some good info on vapor barriers and it seems for some reason, that good info on vapor barriers is hard to find. After addressing this subject many times over the years to help people use vapor barriers and to try and overcome misinformation, I have composed my own more generalized write up that I think may be easier to understand. For what its worth, here it is as I posted it on the Yahoo hammockcamping group earlier this year:

    My Thoughts on Vapor Barriers... again <grin>

    Vapor barriers aren't that easy to use if you don't understand what is
    going on and they aren't that hard to use if you do. Does that make
    any sense? If it does, you don't need to read any further. If it
    doesn't, then read on and I will see if I can help it make sense for you.

    I use plastic or silnylon as a vapor barrier between my hammock and my
    SnugFit Underquilt. The suspension system on the SnugFit helps keep
    the vapor barrier against the fabric of the hammock to minimize air
    gaps that would encourage insensible perspiration to condense and
    pool. With the vapor barrier held in place against the underside of
    the hammock fabric, the hammock fabric wicks away any slight buildup
    of insensible perspiration where it can more easily evaporate and I
    usually don't even notice it. I pick when I do that and understand
    how to use it. It is been very effective for me at extending the
    lower temperature range that I can use my underquilt. I would not use
    a vapor barrier when I was using the underquilt in warmer conditions
    because then I would be dealing with sweat and there would be larger
    amounts of sweat/moisture to deal with as the vapor barrier would
    cause me to overheat even more and prevent moisture from sweat from
    passing through the breathable underquilt.

    In general, breathable insulation works best when your insulation is
    getting too warm for you and less breathable insulation works best
    when your insulation is not quite warm enough for you. That has
    everything to do with how, when, and why your body produces sweat (or
    sensible perspiration) and insensible perspiration.

    Your body produces sweat to help cool off at the outer surface of your
    skin with evaporative cooling when you overheat. Your body does not
    produce sweat when you are not overheating... you don't just leak
    water through your skin all the time. When you are not sweating, your
    body can produce insensible perspiration to keep your skin from drying
    out. If your skin is moist enough, or not too dry, your body doesn't
    produce insensible perspiration because it senses that it doesn't need

    It takes energy for your body to produce insensible perspiration.
    When you are not overheating and your skin is not producing sweat, a
    vapor barrier will cause your skin to quit producing insensible
    perspiration after some period of time. Your skin quits producing
    insensible perspiration because the vapor barrier creates a high
    humidity environment by trapping the moisture from your previous
    insensible perspiration. When this happens your body does not use
    energy to produce that insensible perspiration anymore and can use
    that energy to help keep you warmer. It a sense, your body becomes a
    more efficient furnace.

    A vapor barrier is not so good when used at the wrong time or when
    used incorrectly. When you are overheating and using a vapor barrier,
    your skin continually produces sweat as a means of cooling off via
    evaporative cooling. The vapor barrier prevents the evaporative
    cooling because the sweat is trapped by the vapor barrier. You just
    keep sweating and moisture can build up. You need to do something to
    keep from overheating because what your body is doing isn't working
    because of the vapor barrier. You need to remove the vapor barrier,
    vent, or remove insulation.

    When you use a vapor barrier with breathable insulation between it and
    your skin, that breathable insulation is subject to getting moist or
    even wet from insensible perspiration. The insensible perspiration
    will initially pass through the breathable insulation and stop when it
    hits the vapor barrier. This continues until the humidity builds up
    enough for skin to quit producing insensible perspiration. But until
    that happens, that breathable insulation is going to be getting moist
    too. What you want is a thin wickable sheet of fabric between you and
    the vapor barrier such that it can wick any slight moisture buildup
    away where it can evaporate into the surrounding air. Of course it
    helps for the surrounding air to be able to absorb that moisture
    because if it can't, it won't and you will be clammy.

    And of course, if you use breathable insulation between you and a
    vapor barrier while you are overheating, you will soak that breathable
    insulation with sweat (sensible perspiration). That is bad and that
    happens when people don't understand how and when to use a vapor

    Vapor barriers work well for people that know when and how to use them
    and are often problems or even disasters for people that don't.

    Dave Womble
    aka Youngblood AT2000
    designer of the Speer Segmented Pad Extender, SnugFit Underquilt, and
    May 13, 2008
    Youngblood AT2000

  8. #8
    Senior Member Graybeard's Avatar
    Join Date
    May 2008
    Southwest Vermont
    Modified Speer
    PenTarp, by OES
    Complicated subjects require complicated explanations. This one is well done. Congratulations.
    I found that just reading it left me confused but taking the time to study it was well worth the effort. Thanks for making the effort to share it.

  9. #9
    just curious pan, since it seems you are dead set against using a pad,

    what do you do, or suggest others do, when they are at the bottom end or below their jrb quilts comfort range?

  10. #10
    Senior Member TiredFeet's Avatar
    Join Date
    Sep 2007
    TeeDee Bridge Hammock
    Customized JRB
    Down or IX
    Whoopie Slings
    Quote Originally Posted by warbonnetguy View Post
    just curious pan, since it seems you are dead set against using a pad,

    what do you do, or suggest others do, when they are at the bottom end or below their jrb quilts comfort range?
    A second question for Peter_Pan - you have explained in the past that you tried using pads in the hammock, but for various reason they didn't work for you.

    Did you ever try using one under the hammock instead of in the hammock?

    I notice that your BMBH is double layer for a pad - the sensible way to use a pad in my experience, instead of laying directly on the pad itself. Like slowhike's experience

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