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  1. #1
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    Where to add space blanket to climashield UQ

    Hello,

    I'm new to this forum, here is my introduction post :
    https://www.hammockforums.net/forum/...ad.php?t=70965

    I have a question regarding a climashield apex 4oz UQ I'm planning to make.

    I have ripstop breathable nylon as the UQ shell (both top and bottom layers) and would like to add a space blanket somewhere because I found the 4oz climashield to be just a little short in terms of isolation. I'll be sleeping in temperatures as low as 2C.

    My question is : where should I put the space blanket ? Inside the ripstop nylon shell of course, but under the climashield or above ? Since a space blanket isn't breathable I'm afraid of "plastic feeling" I might get from putting it close to me.

    Thank you,
    Biales

  2. #2
    Boston's Avatar
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    The mylar next to the hammock will block your body heat from warming the air trapped in the insulation - which is part of what helps provide warmth. It may also lead to excessive moisture.

    I'd put it next to your outer shell layer. It'll block wind, but the loft will keep a breathable section for moisture control. Plus the CS can withstand some moisture and maintain it's insulation properties.



    I have to add, too, that typically 7.5 oz of CS Apex is rated for 0*C. You may want to consider adding an additional layer of 2.5oz to your quilt, unless you're a very hot sleeper.

    I'll also add my advice is purely theoretical, as I don't have direct experience with your request. But I did stay at a Holiday Inn Express last night...

  3. #3
    Yoda's Avatar
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    The vapor barrier should always be closest to your body.

    Warbonnet used to make quilts with a snap in space blanket (well wasn't a space blanket it was thicker but same concept) you could use this to boost the temp rating of the quilt when needed.

    Me personally I would not sew it into the quilt, JMO and take it FWIW.
    Formerly known as "Cranky Bear"....

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  4. #4
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    Quote Originally Posted by Cranky Bear View Post
    The vapor barrier should always be closest to your body.
    I'm not an expert in this area as far as an UQ is concerned, but I do have plenty of experience in extreme weather situations and this statement doesn't coincide with cold/wet weather protection or layering concepts that I'm familiar with. Every system that I've used has the first layer as a moisture wicking layer which keeps you dry (polypro). The next layer is the insulation layer to trap and warm air (fleece, down, etc...) with the third layer being the vapor/water repelling layer (gore tex or what have you) to keep the whole system dry. Now this pertains to clothing systems but would the same not apply?

  5. #5
    Yoda's Avatar
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    Vapor barriers act effectively when they are close to the body as they are designed to create a micro climate, thus keeping the body warm by trapping the heat and moisture, thus reducing effective heat loss. If the vapor barrier is on the outside of everything then it will trap everything in and soak all layers underneath it. Go for a hike with your rain jacket on over top of your insulation and you will sweat and eventually wet out your insulation and by doing so will loose all warmth capabilities that the insulation could have provided.

    Vapor barriers are a different beast all together.

    Andrew Skurka used a vapor barrier system for his Alaska trek, and it worked effectively. I will see if I can find the links for systems like this which can explain it a little better than I can.
    Formerly known as "Cranky Bear"....

    "yesterday is history, tomorrow is a mystery, but today is a gift---thats why its called a present" - Master Oogway

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    Andrew Skurka's website and article about Vapor Barrier Liners is very interesting and I learned quite a bit in a short amount of time. While reading it I realized a few things.

    A: The systems that I have experience with were designed for survival while submerged in cold water which has different priorities and thus don't apply as much in this situation.

    2: VBLs work but aren't always appropriate, so more research for your intended purpose is necessary to ensure the system will be most effective.

    III: It seems that the best cold weather system would have 4 layers (outer waterproof then insulation then VBL and then a base layer for comfort to keep the moisture off the skin but still in the microclimate)

    Lastly: Back to the topic of the thread since the system is going outside the hammock and also wont fully enclose Biales then the space blanket would be ineffective as a VBL. This being the case I wouldn't sew it into the UQ, maybe leave it separate and try it both under and over the UQ to see which works best.

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    Link to the article for any interested.

    http://andrewskurka.com/2011/vapor-b...y-application/

  8. #8
    Yoda's Avatar
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    Glad you found it, sorry been busy with other things at the moment. There are other various articles on the web and a couple posts here on HF about vapor barriers.

    I will say that Warbonnet used to make a underquilt with a snap in liner (space blanket type) and it was made to be in between the quilt and hammock, it worked extremely well.
    Formerly known as "Cranky Bear"....

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  9. #9
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    Quote Originally Posted by Biales View Post
    My question is : where should I put the space blanket ? Inside the ripstop nylon shell of course, but under the climashield or above ? Since a space blanket isn't breathable I'm afraid of "plastic feeling" I might get from putting it close to me.

    Thank you,
    Biales
    For an underquilt, I would leave the space blanket loose and just tuck it between the hammock body and the quilt. I recommend the AMK HeatSheet as they are far less noisy. I have used a space blanket with the Hennessy SuperShelter system and with "Garlington insulators" and it adds a lot. I tested extensively for problems with condensation and there was very little moisture that gathered. I did NOT test in sub-freezing conditions, but had no problems at 40F and 95% humidity.

    The seal between hammock and underquilt has a lot of loose edges and is too well ventilated in most cases. The tendency is for warm air to rise, so the fears of vapor accumulating in the bottom insulation are overrated I think. Think about it-- have you ever had much moisture accumulate on a sleeping pad on cold ground? Your top quilt is another matter.

    I recommend an underCOVER to help with cold weather. It provides another layer with added wind blocking and rain protection. I had one made that is also a poncho. 2QZQ makes undercovers too http://www.2qzqhammockhanger.com/ham...cessories.html.

    The idea that you are warming the air under you for insulation is a little inaccurate. The concept to grasp is that there is no such "thing" as cold, only more or less energy. When you insulate, you are trying to keep cold air from circulating and picking up energy from your backside and transferring that out to the cold moving air outside-- convection. That's why the newer generations of air mattresses are insulated-- to stop the air from circulating and transferring the heat from your body to the cold ground. We use down and polyfill because it can be compressed, it bends and moves with us, and it can be laundered, but the concept is the same.

    The reflective qualities of a space blanket only work when very close to your body, but not touching. Other than that, they block wind and moisture well. You want the space blanket between the hammock and UQ for best results.

    Vapor barriers are meant to keep your body moisture from accumulating in your insulation and used mostly in sub-freezing conditions. As your body moisture migrates out into the insulation, it gets to the colder outer layers where it condenses and freezes. On a multi-day trip, your insulation will accumulate moisture and ice until it is useless.

  10. #10
    Senior Member DemostiX's Avatar
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    Too much ideology

    Sleepers don't know their own needs until they are not met. Some naturally transpire a lot during sleep. Some of those have keen feedback mechanisms, so a vapor barrier near the skin, causing high humidity, shuts down that sweating.

    What does not get acknowledged here is that our hammocks have different abilities to wick away moisture, including condensate. Analogize it to a sweat band for your brow. Well designed, not overloaded, and seriously wicking, they are a solution for many. For others, they are all worse than going bare. Some of the high price of "high-performance" fabrics, including fleeces and outer-shells is due to real performance. Some disappointment in them is due to their not working outside of their usually unspecified operating conditions.

    We would know a lot more with more good data, such as repeated measurements of under-quilt weights before and after a night's use.

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