MYOG: tyvek ground cover / bivy combo

[t.darrah]

I completed my secound tyvek ground cover / bivy this weekend. My basic concept is a tyvek ground cover with an attached tyvek cover to form a basic bivy. I will post the finished weight after having a chance to weigh on the postal scale at work (if you currently have a tyvek ground sheet weigh this and multiply buy two, that will get you close). My first attempt kept me dry inside and out during light rain and cool temps. I took more time and greater care with this secound attempt, the next step is additional testing. As with my first attempt I used high tech bonding (superglue type adhesive) in place of sewing the material. I took pictures during the fabrication process and if I can figure out how to post them I will inlude photos in a future posting. I can email pictures upon request, just send me a PM. If someone is interested in trying my concept out send me a PM, I would gladly build one or two for others to test. This was a fun project that I hope to continue to refine and improve. If the product performs well and there is an interest I may make some to sell in the near future. Future options will include a sleeping pad sleeve and a gear storage pocket at the head, all fabricated using tyvek fabric and adhesive.

[Robert Merrick]

I have heard that Tyvek really does work for a bivy. I purchased a survival bivy that I thought was Tyvek or a material like Tyvek. I ripped the fabric along one side with my tossing and turning the first night. How robust is your Tyvek bivy? I would love to see a picture of your design. Also, I tried the tape sold at lowes on some Tyvek with ok results. What brand name glue are you using?

[chris Mcfarland]

id love to test a bivy for you. i tarp with a 5'by7' tarp and a bag cover style bivy and live in the northwest. i cant imagine a more rainy place to test it. let me know. call dot me dot pecos at gmail dot com

[t.darrah]

I completed the tyvek bivy project this weekend and I feel pleased with the result. I will have pictures and a finished weight ready later today that I can email to anyone with interest. Send me a PM with your email address. Maybe someone that I email these pictures too can help me post them on site. I plan to make two or three to send out to testers, for free, as long as they agree to post findings on site for all to read. This project is one of the most interesting things I've undertaken in awhile.

[t.darrah]

The tyvek bivy weighed in at just under 11 oz completed. I have a picture of the scale while weighing the bivy that I can email with my fabrication pictures. This weight included an extended head area on the ground sheet and two inch bonded overlap at all seams. If I cut down the seams to 1" overlap and eleminate the extension I could get the weight very close to 8 oz. Remember this concept will eliminate the need for a ground cover, with that in mind I do not think the weight is to bad, not UL but light.

[Casey Bowden]

I've posted some of the photos Thom emailed me below. I'd certainly be interested in trying one out. However, I'm not interested in having the bivy extended in any way to store my pack or other items while I sleep. I use a trash bag as a liner in my pack, and if it might rain I can put my pack and anything else in the trash bag.

Other thoughts:

1) What is the girth (circumference)?

2) Have you considered a tapered profile to save weight?

3) Is Tyvek truly waterproof (if your sleeping in a puddle for example)?

[Christopher Chupka]

Would a hot glue gun work better than superglue, wider bond?

Will the hot glue get brittle?

Just curious, have you tried it?

[t.darrah]

Casey,
Thanks for posting the pictures. The bivy pictured does have a taper, from head to foot, but it could be more pronounced. I will post measurements used soon. DuPont states that moisture vapor can pass through the fabric but not mostiure itself. I have had good results to date with protection from below 9wet ground) and above (light rain). I will be making three models for others to test, the test models will be provided to testers for free with the agreement that they will post pictures and comments on site for others to review. The thing I liked about the glue I used is that it is an adhesive / sealer, so I sealed the seams while bonding the top and bottom togeather.

[Joshua Mitchell]

Mmm… depends on the kind of hot-glue you use… some get a bit brittle…

I might actually attempt making one of these using gorilla glue…

[Anthony Weston]

I'd be glad to test a bivy as well. I've been thinking for sometime about a tyvek bivy. I love my tyvek groundcloth.

[chris richardson]

Where do you guy's get your tyvek at?

[t.darrah]

I will be making three tyvek ground cover / bivy combos (aka: cocoon)for testing. I will provide the bivy free, icluding shipping, in return I would want the testers to agree to post pictures and comments on this site for others to see and read. I would like one tester from the west coast, one from the east coast and the third I'm open. Casey, whom posted a few pictures for me is first in line. Send me a PM (you to Casey)showing an interest in being a tester. If selected you will need to agree to post findings, provide bag type and size and anything else I may need to know. I will build the test bivy's ("cocoons") and have them ready to send to testers before the end of March.
Thanks for the positive comments and interest in the idea.

[peter kvamme]

If they arent already spoken for, I would be interested in trying out one of the bivys.
I am in the midwest, and primarily camp on the Superior Hiking Trail.

[t.darrah]

My latest prototype shown by Casey (see above) had an upper girth of 74" tapering to 56" at the foot. I will likly taper to something closer 52" at the foot in my test models. The bivy shown has an extended bottom sheet at the head and bomber 2" overlap bonded (and sealed) seams. This prototype weighed in at just over 10 oz as shown. On one test model I will use 1" overlap seams and no ground cover head extension to provide a weight reduction that may interest most.

[Anthony Weston]

On 2nd thought count me out as a bivy tester; I'm on vacation the last two weeks of march.

[Joe Geib]

I'm drooling to see the dimensions of the bivy. I want to make my own.

[t.darrah]

I have selected one tester, Casey, and will pick the final two soon, are there any females interested in testing a prototype? The prototype shown, by Casey, did not have the hood completed, I may ask Casey to post a picture with the hood completed as he is getting the model shown as his test bivy. The final measurements and weight are still being refined as I develop the concept. Much depends on size and type of sleeping bag being used. I may further refine the seam allowance to reduce weight if strength is not an issue. I plan to make one test prototype using 1" bonded seams in place of the 2" as in the model shown.

[Diplomatic Mike]

Whilst reading this a thought came to me. What about using a Tyvek hooded work suit ( think crime scene forensics ). They only cost a few $s. You could buy a XXXL and cut the arms off and re-seal. Unpick the inner leg seams and re-seal as a bag. You then have a hooded bivvy-bag with a top zip. Is this too simple? Must try it out!

[Anthony Weston]

I tried the tyvek hooded work suit. The material is much thinner than what is usually used for a ground cloth. They only weigh 5 oz. I purchased mine from uline. The zipper would need to be seam sealed. It might make a lightweight emergency raingear however you'd look like you escaped from a lab experient gone wrong. I do have down pants, I'll have to test it out in the backyard as bivy suit. However so far I don't see it as something I'll use backpacking. It did not seem to add any warmth and there are small pinhead size holes, maybe I'll wear it in the shower and find out how waterproof it really is but I don't think it's a threat to driducks.

[t.darrah]

I posted pictures of my latest prototype on BPL yesterday, I have now completed three tyvek GCB prototypes and have sent them to BPL members for product testing and reviews. Each will post their test results on line for others to read. If reviews are positive I will fabricate standard and custom models for sale.

[Margo Costas]

I would like to test a bivy but the test would have to be in my yard. I always weather test my stuff in the yard before I go into the real world. I should be getting my oware tarp soon and will be practicing with that in the yard. I understand though if yard testing isn't what you had in mind.

I am glad I clicked on this thread as I have been wanting something to protect my down bag if my rainbow tarptent or oware tarp fails to keep me dry. At any rate I will probably attempt a tyvek bivy myself so I am interested in seeing the other testers results.

[t.darrah]

My project is coming along great, I have now completed three prototype test GCB's and they are each on their way to a tester. I've had additional interest in testing that I'm trying to accomadate but your the first female to show an interest. Please PM me your sleeping bag type and size and also the location/area you would use for testing. I will share with you my test priorities and let you know when I can have a test GCB to you. Thanks for showing an interest in my project.

[Joe Geib]

Tom,

Any update on the pattern/details for making one, or selling them yet?

[Matthew Robinson]

casey, about your thoughts on tyvek truly being waterproof. i worked with stucco and had to staple tyvek alot and i remember seeing scrap pieces in puddles all day not soaking up a stitch. however, there was no weight on them, but im suspecting your body would compress out any water beneath you. not really a straight yes/no answer but its the best i can do. considering cheap bivys start at $100 i can handle anything my $20 tyvek throws at me.

for the reviewers, if maybe you could comment on moisture build up maybe with/without VBL.

i got a gang of tyvek and this thread is right up my alley.

aloha

[t.darrah]

Joe Geib,
I have four prototypes out for testing by BPL members at this time. I will be posting pictures of a second model soon. I'm also currently building a double GCB that will sleep two per the request of a BPL member. My bonding method, fabrication quality and speed improve with each GCB made. I have refined the taper and a size regular (fits 6') in a classic slide in style now weighs right at 8 oz., this is with bomber 2" overlap seams. I'm working on testing 1" overlap seams now which will help reduce the weight further. If the tests come back positive I will be offering these for sale in standard models and also custom. Thanks for your interest in my GCB project.

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