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Challenging weather- how would you handle this situation?


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  • #1298737
    Ike Jutkowitz
    BPL Member

    @ike

    Locale: Central Michigan

    I just got back from a 4 day trip along the Lake Superior Shoreline in Ontario. Freakish weather fluctuations made for some unusual challenges. I'm curious how others would handle this situation.

    Day 1. Blizzard conditions, Highs of about 32-34 F, overnight lows in the 20s. Trail involved a good amount of climbing, scrambling, (and falling) with melting snow a problem.
    Solution: Managed moisture by hiking in only base layers, shell pants, and wind shirt. Brushed off snow frequently. Cool down period before setting up camp left clothing dry-ish.
    Outcome: Slept in pyramid tarp, DWR bivy, 0 F quilt. Wore only baselayers and VBL rainsuit (silnylon). Comfortable night sleep, but found more condensation in bivy than I am used to, particularly between my sleeping pad and sil-nylon floor.

    Day 2. 27 F and freezing rain all day long.
    Solution: Hiked in only base layers and VBL rain suit, sacrificing these to assure dryness of all other clothing.
    Outcome: Kept warm by hiking continuously. Rain suit soaked through, base layers drenched. Put all in plastic bag and changed into dry R1 mid layer and shell pants to sleep in. Unable to use VBL- too wet.
    Outcome: Slept blissfully. Quilt shell noticeably more damp by morning, but still warm and lofty.

    Day 3. Back to snowing. Temps dropped to single digits. 20 MPH winds
    Solution: Put on damp base layer bottoms with shell pants on top. Put soaked base layer top on top of R1 top and hiked until warm and dryish, then flipped them and hiked some more. By 11 am, all clothes felt dry and warm to touch. I had "reclaimed" all clothing except for sock system, which remained persistently wet but warm as long as moving.
    Outcome: Slept in baselayers, shell pants, windshirt, and R1. VBL suit was now frozen solid and could not be used. By 3 am, I was noticeably cooler. Over my lower half where the quilt was still in the bivy, ice had formed between the two layers but loft was maintained. Over my torso, where I had pushed back the bivy to promote ventilation, baffles were damp and almost completely collapsed. I fluffed as best I could and slept warmly till morning. I later found out it had dropped to -11 F overnight.

    Day 4- All clothing dry and fully functional. Quilt shell frozen in spots, torso loft clearly suffering, but still had maybe one good night left if needed. Temps -2 to 4 F. Finished the trek by evening. Back home, quilt once thawed was very damp. If I had unexpectedly needed to spend additional nights out, things would have gotten challenging in the next couple days without a drying fire.

    I think the first two days set me up for a lot of moisture in various layers that lead to a more than expected amount of condensation during the overnights. I'm looking for some experienced perspectives about how you would handle these conditions.

    #1949809
    Brendan Swihart
    BPL Member

    @brendans

    Locale: Fruita CO

    Hope we'll be getting a full report and pics on this one, Ike, sounds like a badass trip ;) Sounds to me like you managed things pretty well with what you had. One thing that might have helped manage moisture in your sleep system is a bit lighter down quilt + lightweight syn quilt combo (I usually skip a bivy and use a plenty wide 2.5 oz climashield quilt over my 30* quilt). Some hot water bottles in the bag might have helped push out some moisture as well. A fire would have probably dried out the sil VBL pretty quick.

    Interesting that you lost more loft on the third night where the bivy wasn't over you on your torso….

    Great post, lots to think about.

    #1949815
    James holden
    BPL Member

    @bearbreeder-2

    youve found out the hard way what happens when there is no opportunity to dry out your gear in the sun/wind

    as you noticed

    1. a bivy doesnt have the best ventilation, and this itself can result in condensation

    2. the flip side is that if you use the quilt as your outer layer, this can also result in dampness as the moisture collects in the last layer

    3. you shouldnt have needed to hike in a VBL at those temps … you likely sweated it out, resulted in it freezing later in the trip … save the VBL should you use one for sleeping at those temps

    4. was you clothing damp at any time when going to sleep? … the moisture would go directly to your quilt … did you have any down puffies that you used under the quilt?

    solutions

    1. a light synth over quilt/bag … it will add 15-20F to your system, and the dampness will transfer to it rather than stay in your quilt … as a bonus you use it in the summer, or at rest stops, or in camp …

    2. a hawt nalgene when sleeping will help push the moisture out of the quilt/bag … this of course requires extra fuel and those darn heavy nalgenes

    3. sleep with any damp clothese outside the bag … also consider drapping any puffies, rain jackets (only breathable ones), etc … on the outside of the quilt … you may "sacrifice" tem by getting them damp, but they are easier to dry, especially when active … you down sleeping gear is the most essential piece of insulation you have, dont get it wet … period …

    4… ventilation of the tarp and camp location … that you should be able to judge and manage as best you can

    an interesting question would be whether a VBL bag would have been more effective, perhaps the VBL suit holes allowed moisture to escape into your sleeping system … hmmmm

    were you sweating quite a bit in your VBL when sleeping?

    #1949823
    Stephen M
    BPL Member

    @stephen-m

    Locale: Way up North

    Hi Ike,

    I encountered similar conditions on a trip in Ireland last year, using a double wall tent with a solid inner (well ventilated) really helped and putting a synthetic jacket over the chest of my down bag helped keep the bag dry at night, during the day I was wearing a event jacket and trousers which kept me fairly dry, the double wall tent, synth jacket and rain gear do add a bit of weight but kept me dry and comfortable.

    Also I was on a trip in Canada recently in the similar conditions and I was the only person in the group using a double wall tent and my bag stayed nice and dry where as the guys using floor less shelters for soaked, I suspect as they did not have ground sheets any moisture on the ground condensed on the tent walls and droplets came back down and soaked their down bags.

    Cheers,

    Stephen

    #1949824
    Justin Baker
    BPL Member

    @justin_baker

    Locale: Santa Rosa, CA

    Never underestimate the utility of a nice warm fire. On really cold nights, I have sat there and dried out my wet clothes by the fire just to give me a little more warmth. It also gives you chance to dry out your bag or even keep it going all night long if necessary.

    #1949826
    Nick Gatel
    BPL Member

    @ngatel

    Locale: Southern California

    Day 1. Blizzard conditions, Highs of about 32-34 F, overnight lows in the 20s. Trail involved a good amount of climbing, scrambling, (and falling) with melting snow a problem.
    Solution: Managed moisture by hiking in only base layers, shell pants, and wind shirt. Brushed off snow frequently. Cool down period before setting up camp left clothing dry-ish.
    Outcome: Slept in pyramid tarp, DWR bivy, 0 F quilt. Wore only baselayers and VBL rainsuit (silnylon). Comfortable night sleep, but found more condensation in bivy than I am used to, particularly between my sleeping pad and sil-nylon floor.



    Hard to say there are so many variables. However you state you slept in your VBL rain suit and there was condensation in bivy. This really can't happen unless you are breathing into the bivy.

    #1949828
    Ike Jutkowitz
    BPL Member

    @ike

    Locale: Central Michigan

    Brandon,
    Thanks for your comments. I will definitely put together a trip report, though this was one better lived than photographed.

    Eric,
    Thank you for weighing in. I know this is an area of interest for you. For clarification, I never hike in VBL. In this case, I was hiking in pouring rain at 27 F in 1 1/2 feet of snow, wearing only capilene 1 baselayers and the only rain suit I had, a silnylon suit I had brought for the purpose of sleeping in at sub zero temperatures.

    I was not overly warm (or cold) on any night. The first two nights I simply kept the quilt loosely draped over me, venting as needed.

    A point for discussion- bivys get a bad rap for condensation, but it has been my experience that in winter, the dew point is usually between the quilt and the bivy. Moisture that condenses in this area freezes quickly and is easily brushed off. Without the bivy, condensation develops beneath the quilt shell, within the insulation. On this trip, I don't think the bivy worked in my favor on the first couple nights, but I'm not ready to write them off yet, given years of otherwise positive experience.

    Nick,
    The silnylon suit functioned poorly enough as a rain suit that I now question how well it did as a VBL. Especially after it froze solid. This made me think it had absorbed water or at least allowed strike through. Contrast this to a truly waterproof material like my cuben duomid. This too got very wet, but when temps dropped below freezing, the ice crystals easily shook right off of it.
    On a similar note, the bivy I was using was new, purchased in a size wide enough to allow my quilt and pad combo to fully loft. Because the first sign of condensation was between floor and pad, I again questioned the possibility of strikethrough under contact.

    #1950188
    Eric Blumensaadt
    BPL Member

    @danepacker

    Locale: Mojave Desert

    Pyramid tent/tarp designs ain't my fav.

    Unles you dig down at least 1 ft. into snow to give it "walls" you lose floorspace all around the edges.

    Then too, most pyramids don't vent well.

    And there's that pesky center pole…

    Try a nice, double wall winter tent, dome, tunnel or a hybrid like the TT Scarp. Get one with good venting.

    #1950190
    Eric Blumensaadt
    BPL Member

    @danepacker

    Locale: Mojave Desert

    Your situation(s) are why the new DWR treated downs are going to be popular. Much less moisture absorbed and better lofting when dampish.

    But Climashield synthetic insulation is still (IMO) the best bet for the conditions you experienced. It will maintain loft over time better than any of the Primalofts.

    As for clothes, I still feel synthetics for every layer is best, with merino wool next best. The newer polyester long johns with the fleece lining gridded into tiny squares seems to have the best warnth-to-weight ratio – for now, at least.

    #1950291
    Ike Jutkowitz
    BPL Member

    @ike

    Locale: Central Michigan

    Thank you for the replies. I'm actually quite happy with my gear and am not looking to purchase anything new. Double wall tents certainly will provide a warmer local climate and help to shift dew point outward. However, I used a double wall tent for 20 years and discovering the freedom of tarps and other minimal gear has led to significant improvements in hiking style and accomplishments. Hopefully this satisfaction comes across in my trip reports.

    I was hoping to shift this discussion more towards techniques for moisture management in challenging conditions. I should point out that the conditions I encountered, (day 1) warm wet snow, (day 2) freezing rain, (days 3 and 4) sub-zero are fairly uncommon in the frozen north and consequently not something I have to deal with regularly. I'd expect many of you in other parts of the country (pacific northwest) see these conditions routinely.

    Some things I have been thinking about in particular (thanks Eric) have been:

    1. Ways I allowed moisture into my system. Slipping and sliding through warm wet snow probably allowed for more moisture in my clothing system than I expected. Though I limited the amount of clothes I brought into my quilt, I probably underestimated this effect. This was compounded on day 2 when continuous rain, soaking wet base layers, and compromised VBL/rainsuit led to my sleeping in damp clothes inside the quilt.

    2. Using a standard silnylon rainsuit may not be the optimal VBL due to excessive venting through the arm, leg, and neck holes. A designated smaller suit with closures at wrist, ankles, and neck might do better. The VBL sack would probably be more effective, but would limit two uses of the VBL- wearing insulation over the suit if needed, and putting on the VBL at rest stops to limit moisture transfer to my insulation layers.

    3. One big question I had wanted to talk about was whether layering techniques (ie bivy) improve or worsen moisture control. In this excellent discussion by Gordon Giesbrecht, he suggests that the use of layers increases the likelihood that moisture will condense between layers where it freezes and can be shaken out (see diagram below) rather than condensing within the insulation. This has been my experience in colder conditions, but unfortunately, it was not cold enough on the first two days to allow this, so the condensation soaked back through the shell.

    dew

    Does the decrease in ventilation from a thin, breathable bivy offset this potential advantage, or would the condensation just form beneath the shell layer of the quilt? When right at the danger zone for condensation (just below to just above freezing, omitting the bivy may make the most sense.

    @Justin- no doubt the time spent drying gear can be time well spent. On this trip, it was always raining or snowing hard enough that sitting out by a fire would have led to additional precipitation on the quilt that would have been hard to avoid.

    #1950292
    Stephen M
    BPL Member

    @stephen-m

    Locale: Way up North

    I was using a 3 person double wall tent last night with 2 buddies in minus 13f and it ws snowing inside the tent this morning as we got no airflow at all as it was a still night.

    #1950298
    Dale Wambaugh
    BPL Member

    @dwambaugh

    Locale: Pacific Northwest

    Sounds like a spare set of base layers would have helped. If the temps dropped that low, I would have gone for a fire too.

    Regarding the condensation under your pad: did you have a ground sheet too? Covering the whole floor area can keep the inside of a tarp shelter drier and it seems that the bottom of the bivy was allowing some moisture to seep through. Some polycryo would be light and effective.

    #1950319
    James holden
    BPL Member

    @bearbreeder-2

    in theory the moisture should collect in the bivy, freeze and you should be able to shake it out … but that assumes that everything isnt wet and damp, typical PNW conditions, and much colder …. and at more moderate temps IMO it may make things worse with less ventilation, and the moisture can soak back into the quilt … at least one BPLer had this type of issue before

    i think its fairly significant that when the temperatures dropped, and things were allowed to freeze, the bivy became more effective for you and you saw the difference between having a bivy vs. the quilt as your last layer

    the "band aid" (i wont call it a solution) is of course a hawt nalgene to push the moisture out … and a light synthetic overquilt/bag …. or putting your synth/fleece jacket over the bag at night (or between the quilt and the bivy) … that way the moisture gets absorbed into the synth, which basically dries out with body heat and a nalgene

    if your clothes are damp (not wet) you can drape em over your quilt

    as you can tell im a big fan of nalgenes and synth over down … ive dried out quite damp down jackets that way …

    #1950367
    Jason Elsworth
    Spectator

    @jephoto

    Locale: New Zealand

    I don't think you could have done all that much differently with the gear you had. However, a set of dry sleep clothes and a set of waterproofs (allowing the VBL suit to be used every night)would have helped.

    #1950381
    Roger Caffin
    BPL Member

    @rcaffin

    Locale: Wollemi & Kosciusko NPs, Europe

    > discovering the freedom of tarps and other minimal gear has led to significant
    > improvements in hiking style and accomplishments.
    Maybe so, but the margin for error shrinks a bit. What you have really found is that tarps are not a solution for all conditions. This is especially true for cold wet conditions. Nice idea, but …

    > Slipping and sliding through warm wet snow in a pair of insulated pants and fleece
    > top on day 1
    This sounds like excess clothing being worn. A common mistake. You should try to wear the absolute minimum of clothing while travelling, so that what gets wet is not critical. I know the usual reply is 'but I will get cold', but we don't: we generate enough heat from within. When you stop, then the extra clothing goes on (pretty quickly).

    > my sleeping in damp clothes inside the quilt.
    Never do this, at least not in cold conditions! Big mistake. Do not put moisture into your quilt! And this means sleeping a little cool, not hot and sweaty.

    The illustration was a bit misleading. The idea in the right-hand bit ONLY works in above-freezing conditions. When it is below freezing, trying to pump moisture thru a quilt into air which is below freezing does not work the way shown.

    > would the condensation just form beneath the shell layer of the quilt?
    Sure can. Using a bivy over a quilt in sub-freezing conditions can be risky.

    > techniques for moisture management in challenging conditions.
    Leave your wet clothing outside your quilt: do not ever risk getting the quilt damp! Yeah, pain and suffering in the morning when you get dressed in your wet clothing at the last minute, but so what? If it is still wet weather, you will be wet soon enough. If it has cleared up, your clothing will dry soon. Drying clothing overnight is really a bit of a waste of time.

    A good trick is to carry a couple of large plastic bags. Put your wet shoes and your wet clothing in plastic bags, seal them up, and stick them at the foot of your quilt on insulation. Under your feet if you like. They should stay at least a little 'warm' overnight, so the shock in the morning is not too great.

    Cheers

    #1950392
    James holden
    BPL Member

    @bearbreeder-2

    ?The illustration is basically fraudulent advertising, probably by Gore.

    the illustration is from http://umanitoba.ca/faculties/kinrec/research/media/Cold_Weather_Clothing.pdf

    by …

    Dr. Gordon Geisbrecht, PH.D

    Dr Gordon Giesbrecht is a professor of thermophysiology at the University of Manitoba in Winnipeg where he runs the Laboratory for Excercise and Environmental Medicine, and studies human responses to excercise and work in extreme environments.

    Gordon combines practical experiences as a wilderness instructor with 20 years of human cold research, conducting hundreds of lab and field trials which have led to the publication of more than 100 articles about cold physiology and pre-hospital care for human hypothermia. In 2006, Gordon teamed up with outdoors expert Jim Wilkerson to publish 'Hypothermia Frostbite and Other Cold Injuries'.

    Gordon has been featured on the Discovery Channel, National Geographic and a number of television networks including David Lettermen's Late Show where he actually immersed himself in ice water on live TV to demonstrate the effects of Cold Water Immersion. He has also popularized the effective slogans 'one minute-ten minutes-one hour or 1/10/60' for immersion in icy water and 'Seatbelts-Children-Windows-Out' for escaping vehicles in water.

    this fraudulent bum TEACHES our local SAR teams …

    http://www.coquitlam-sar.bc.ca/2011/10/coquitlam-sar-and-dr-gordon-giesbrecht/

    hes even in yuppie mags …

    http://www.outsideonline.com/outdoor-adventure/outdoor-skills/survival/Meet-Prof–Popsicle.html?page=all

    TO GORDON GIESBRECHT, the world's leading authority on freezing to death, a midwinter dip is just another day at the office. Believing that the best way to study the effects of cold on the human body is to get intimate with the elements, this 45-year-old physiologist and director of the University of Manitoba's Laboratory for Exercise and Environmental Medicine has lowered his body temperature below 95 degrees, the threshold of hypothermia, a mind- and body-numbing 33 times.

    The masochism doesn't stop there. In March 2001, to learn more about how the body metabolizes various energy sources in subfreezing temperatures, Giesbrecht and four other men each dragged 180 pounds of gear across the frozen surface of Lake Winnipeg, a body of water roughly the size of New Hampshire, for 19 days. Then there was that winter 1999 experiment during which, in an effort to cool his body core while keeping his skin temperature constant, he had a colleague inject, over a one-hour period, more than a gallon of nearly frozen saline directly into his bloodstream. "He's a risk taker," says William Forgey, a 60-year-old physician who is the past president of the Colorado Springs-based Wilderness Medical Society. "If he needs to take it to the edge, he does it himself. While the expertise is there and the risk is controlled, it's still dangerous stuff. He's like a race-car driver."

    There is, of course, a very good reason why Giesbrecht keeps getting behind the wheel: This winter, like every winter, athletes, adventurers, and hapless innocents will get themselves into trouble in the cold. While no organization keeps detailed statistics on cold-related deaths in the outdoors, each year hypothermia kills an estimated 700 Americans. An additional 1,800 or so are thought to perish in cold-water drownings.

    Giesbrecht has devoted his academic career to improving the odds for such victims of exposure. He is Professor Popsicle, the King of Chill. He may have a cliché for every occasion—"Keep cool, but don't freeze," he'll say, smirking like Mister Rogers—but he is one of a kind. Or at least a few: There are roughly a dozen scientists worldwide who specialize in human thermoregulation, the study of how the body responds to temperature changes. Only a handful undertake human experiments, and no one goes as far as Giesbrecht, who has intentionally taken his core temp lower—down to 88.2 degrees—than any other researcher. "I'm the scientist who does things for real," he says, "to make sure I really know what I'm talking about."

    ;)

    #1950416
    Steven Paris
    BPL Member

    @saparisor

    Locale: Pacific Northwest

    Hope this is not straying far from Ike's questions:

    Just for clarification, is there a consensus on the ideal temperature and precipitation range of a water-resistant breathable silnylon-type bivy?

    When does it make the most sense? Under what shelter?

    #1950430
    Ike Jutkowitz
    BPL Member

    @ike

    Locale: Central Michigan

    Thanks Eric,
    You've given me some simple stuff to think about.

    Roger,
    The diagram I was calling attention to is the one on the left. The text for the diagram on the right was stating that the only way to actually push water vapor through goretex in cold weather was to greatly increase body temperature (e.g.. through exertion).

    I also apologize for mis-speaking in the last post (slipping and sliding in fleece). As per the original post, I was only in my baselayer and shell pants on day 1- fleece didn't come on till subzero F temps on day 3.

    Jason and Dale,agreed. An extra baselayer would have been nice. I actually had a spare cap 4 top I had thrown in my pack when I knew rain was a possibility. Because I don't normally bring it and because I was never in immediate distress, I elected to leave it in my pack unused to see how things unfolded. Would have loved to have a spare pair of bottoms on the second night.

    #1950545
    James Klein
    BPL Member

    @jnklein21

    Locale: Southeast

    I've never been in quite these conditions so, this is mostly a thought expirement for me.

    I have a fleece vest for when I expect cold and wet. I think it is impossible to stay dry hiking in continuous rain (either leaking raingear or condensing sweat). The vest is part of my warm when wet strategy — never used it below high 30sF. But I probably would have first tried baselayer + vest + wind jacket and just gotten wet and saved the vbl for night.

    I think without a bivy you would have been worse off. I think its an easy call once shelter inside temp is ~30F as the quilt/bag shell will be too cold to pass any meaningfull moisture anyway (therefore decrease in ventilation doesn't really hurt).

    If possible its a big plus if you can elevate the a breathable bivy slightly above you quilt/bag – this helps to keep condensation from being pressed back into the quilt.

    Avoid breathing ANY air in to the bivy. Id rather leave my entire head out of the bivy than than send 5% of my exhaled breath into the bivy. Thick fleece over you mouth helps to capture exhailed moisture.

    Echoing eric, I would also have tried keeping the dampish clothes on top of the quilt vs inside and worried about drying them while moving.

    A wpb bivy may have performed better here as they tend to pull moisure through them.

    All of these may have bought another day or two. To be honest I think you managed pretty well. Double wall tent and other trad get would have likely met a similar fate — cold and wet weather with wet snow is hell on equipment/bpackers.

    Keep up the good work.

    #1950569
    Mary D
    BPL Member

    @hikinggranny

    Locale: Gateway to Columbia River Gorge

    More armchair (or rather, computer chair) quarterbacking:

    My thoughts on reading about your adventure were much the same as Roger's. In wet, cold weather (our PNW winter is mostly like your first two days!), it's really good to have a dry layer to wear to bed, even if it means carrying a second baselayer. I always put the wet stuff in a sealed plastic bag inside my sleeping bag so that it's relatively warm in the morning when I put it on. Of course if you don't do that, you will wake up in a great hurry when you put the cold wet clothes back on! And you'll want to get out on the trail moving really fast!

    I've always used my silnylon rain gear as a VBL in the sleeping bag but I don't go out in below zero weather. Despite the extra weight, it would probably be worth having a separate VBL from your rain gear. You could make the VBL suit a lot snugger which would make both it less permeable and lighter.

    As Roger said, it's vital to keep moisture out of the sleeping bag and your puffy insulating clothing!

    The combination of wet, slushy, soggy weather followed by a couple days of below zero could have had nasty consequences, far worse than if you'd started in below-freezing weather. I'm glad you avoided those!

    #1950586
    steven franchuk
    Member

    @surf

    "Kept warm by hiking continuously. Rain suit soaked through"
    "the only rain suit I had, a silnylon suit "

    This was a big mistake. In those conditions you need to stay as dry as possible during the day. There are 3 ways for your rain suit to fail

    1. the suit had a leak.
    2. The suit didn't breath enough and condensation occurred.
    3. It leaked and didn't breath enough.

    Silnylon doesn't breath. Yes you can open up vents to get the moisture out. But you need to make sure rain doesn't get past the vents and get you wet. Check your suit carefully for leaks and repair or replace the suit.

    My experience growing up in the PNW was that it can be very difficult to vent a waterproof jacket enough to avoid condensation. While event or Polartec Neo Shell would have performed a lot better in terms of condensation. Under heavy exertion there still will be some condensation but that can be managed by slowing down so that the waterproof brathable material catches up, venting the jacket, and or by stoping in a sheltered spot to get out of the rain and dry off.

    If you don't want to get a waterproof breathable suit, get a poncho. They breath very well and will prevent the rain from getting though your suit.

    "Comfortable night sleep, but found more condensation in bivy than I am used to, particularly between my sleeping pad and sil-nylon floor."

    If your pad was inside the bivy, what was between the bottom of the bivy and snow? If the bivy was touching the snow it will be a cold spot in the bivy and condensation is more likely to occur in cold spots. You might have been better off if you pad was between the bivy and the snow. That would provide a thermal brake and hopefully would allow the bivy fabric to stay a bit warmer and reduced the condensation somewhat.

    Condensation inside a tent or bivy will occure then the inside temperature reaches the dew point. there are several ways to reduce condensation in a tent or bivy.

    1. reduce internal humidity. You can do this by keeping wet items out of the bivy. but you can't tell your body to to stop releasing water. Also venting also carrys away a lot of heat meaning the inside will be colder than it would be if you didn't vent.

    2. Vent the tent or bivy so that any excess humidity is swept out quickly. Unfortunately humidity levels cannot drop below the levels outside the ten. So if outside air temperature drops to the dew point air inside the tent or bivy will also drop to the dew point and condensation will occur.

    3. increase the inside temperature. If you can keep the inside temperature high enough condensation will be reduced because the warmer air can hold more water vapor. However to do this you need to you need to reduce airflow in and out of the tent. That means closing the vents as much as possible without completely stoping airflow (you still need to get the excess humidity out). Another way to do this is to use hot water bottles or chemical hand warmers inside your bivy to stay warmer.

    #1950600
    Roger Caffin
    BPL Member

    @rcaffin

    Locale: Wollemi & Kosciusko NPs, Europe

    > The diagram I was calling attention to is the one on the left. The text for the
    > diagram on the right was stating that the only way to actually push water vapor
    > through goretex in cold weather was to greatly increase body temperature (e.g..
    > through exertion).
    Confusing.

    Cheers

    #1950601
    Roger Caffin
    BPL Member

    @rcaffin

    Locale: Wollemi & Kosciusko NPs, Europe

    Hi Eric

    > the illustration is from http://umanitoba.ca/faculties/kinrec/research/media/Cold_Weather_Clothing.pdf
    Turns out diagram was being seriously misrepresented. Ah well.

    > Giesbrecht, who has intentionally taken his core temp lower—down to 88.2 degrees
    Risky. A few can do this, but it is a very good example of "Don't try this at home folks".
    I have gone low, but I doubt it was that low. I was carried out as I was a bit rigid.

    Cheers

    #1950603
    Travis Leanna
    BPL Member

    @t-l

    Locale: Wisconsin

    It's amazing how tiny a sliver of temperature range the human body can function well in. It also highlights the amazing capacity for our bodies to regulate it so well.

    #1950681
    David Chenault
    BPL Member

    @davec

    Locale: Queen City, MT

    Great post Ike, provides lots of good food for thought. I've been out in mixed rain/snow plenty of times, but never had freezing rain and -11F within 48 hours. To be blunt, I doubt many/any of the respondents have. Very challenging conditions, not something to be armchair'd on lightly, and I think you did exceptionally well to have been as comfortable as you were.

    I've never experimented with sleeping in VBL clothing. It just never seemed appealing. I have been using a 100 g/m Primalift 1 quilt with good DWR fabric as an overbag this winter, with great success. It seems to prevent the accumulation of moisture within the inner, down bag to a substantial degree, and if used properly totally prevents condensation from getting the bag wet. I built mine so I can use it as an insulated poncho, which makes it more multi-use and better justifies the weight and bulk. Moisture inside your sleep system and condensation inside your shelter are going to happen in winter. This overbag system is a lot less fiddly way to deal with these issues than the ideas suggested above.

    The other piece of gear which would have been a game changer for you is a wood stove inside the shelter. You'd need a bigger mid, but you could have dried most everything out at night, each night. Seek Outside is working on a heat-only ti wood stove which they claim will be less than a pound all in. If it weighs that much it will, for me, be an always-have item in winter and shoulder seasons.

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