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MYOG: tyvek ground cover / bivy combo
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Thom Darrah
(thomdarrah) - MLife

Locale: Southern Oregon
MYOG: tyvek ground cover / bivy combo on 03/09/2008 12:22:56 MDT Print View

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
(Flyfisherman) - F
Tyvek Bivy on 03/09/2008 22:52:07 MDT Print View

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

Locale: baba yaga's porch
MYOG: tyvek grond cover/bivy combo on 03/10/2008 01:18:29 MDT Print View

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

Thom Darrah
(thomdarrah) - MLife

Locale: Southern Oregon
MYOG: tyvekground cover / bivy combo on 03/10/2008 09:00:35 MDT Print View

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.

Thom Darrah
(thomdarrah) - MLife

Locale: Southern Oregon
Tyvek ground cover / bivy - weight on 03/10/2008 09:55:02 MDT Print View

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
(clbowden) - MLife

Locale: Berkeley Hills
Tyvek Bivy on 03/10/2008 11:06:21 MDT Print View

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

Locale: NTX
Hot Glue on 03/10/2008 11:09:18 MDT Print View

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

Will the hot glue get brittle?

Just curious, have you tried it?

Thom Darrah
(thomdarrah) - MLife

Locale: Southern Oregon
tyvek ground cover / bivy on 03/10/2008 12:09:09 MDT Print View

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
(jdmitch) - F

Locale: Kansas
Re: Hot Glue on 03/10/2008 12:56:59 MDT Print View

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
(anthonyweston) - MLife

Locale: Southern CA
bivy tester on 03/10/2008 14:33:35 MDT Print View

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
(crricha13) - F
Tyvek on 03/10/2008 14:52:39 MDT Print View

Where do you guy's get your tyvek at?

Thom Darrah
(thomdarrah) - MLife

Locale: Southern Oregon
tyvek ground cover / bivy testers on 03/10/2008 16:04:16 MDT Print View

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
(karacolor) - F

Locale: midwest
Re: MYOG: tyvek ground cover / bivy combo on 03/10/2008 16:15:01 MDT Print View

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.

Thom Darrah
(thomdarrah) - MLife

Locale: Southern Oregon
Tyvek ground cover / bivy combo on 03/10/2008 16:20:40 MDT Print View

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
(anthonyweston) - MLife

Locale: Southern CA
bivy tester on 03/10/2008 17:19:26 MDT Print View

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

Joe Geib
(joegeib) - F

Locale: Delaware & Lehigh Valleys
plans on 03/11/2008 07:22:07 MDT Print View

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

Thom Darrah
(thomdarrah) - MLife

Locale: Southern Oregon
tyvek ground cover / bivy on 03/11/2008 08:51:49 MDT Print View

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

Locale: Under a bush in Scotland
Tyvek bivvy on 03/18/2008 11:05:33 MDT Print View

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
(anthonyweston) - MLife

Locale: Southern CA
tyvek hooded work suit on 03/18/2008 11:44:20 MDT Print View

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.

Thom Darrah
(thomdarrah) - MLife

Locale: Southern Oregon
Tyvek GCB (ground cover bivy) on 03/18/2008 12:27:50 MDT Print View

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.