Dec 5, 2013 at 3:27 pm #1310619
Hello everyone. I am going to make a bivy with a cuben floor and .75oz pertex top. I am trying to decide if I should make the floor bathtub like zpacks does or flat like Borah Gear does. Would those of you with Bivy experience, especially as relates to the PCT, mind weighing in on the advantages/disadvantages of each method.
Thanks a lot.Dec 5, 2013 at 4:46 pm #2051254
Andy DuncanBPL Member
Hi James. I've been using a bivy with a cuben bottom, M55 top and 8" bathtub sides. It also has some netting around the head and a 1/2 side zip. I like the 8" bathtub cuben on the sides, it saves some weight (I used the 0.51 oz/sqyd cuben) over the M55 and it does provide some good protection from rain spray. I used it with a small 5.5' x 8.5' tarp on the JMT and it kept me dry and warm during four nights of rain. I noticed a lot of extra warmth and wind protection while cowboy camping. It weighs 3.9 ozs.
I dont' have experience with other designs.Dec 5, 2013 at 5:05 pm #2051269
Andy, Good looking Bivy. Thank you for the info. That if very similar to the design I am leaning toward. I am kind of taking the features I like from different manufactures and mankind a mash up. I will be using a heavier floor material.
Would you mind telling me how wide the floor you made is not including the bathtub walls. Looks like maybe 22"?
Again great design and thanks for the feedback.Dec 5, 2013 at 6:29 pm #2051315
Jamie ShorttBPL Member
@jshorttLocale: North Carolina
James, Here is my MYOG bivy under a small cuben tarp. I recommend creating a pseudo bath tub floor by sewing both ends to form a box like a stuff sack bottom is made. It is extremely easy to do and I find it works fine.
I took these picture the following morning after it had rained much of the night, I slept completely dry. This bivy only has a chest zip, is m50 and .51 oz cuben on bottom and weighs 3.2 oz. I would recommend considering a zip like Andy's, it is well worth the small weight penalty.
I have directions on how to make this bivy on my site…
JamieDec 5, 2013 at 7:43 pm #2051359
Andy DuncanBPL Member
James, The dimensions are about 22” at the head tapering to 32” at the shoulders then tapering down to 24” at the foot end (all with the 10 inch height which includes the 8" bathtub plus 2" of M55). To give some perspective I am 6 feet/190 lbs. Having enough shoulder/elbow room was important and it seems to have worked fine.
Here is a link with more details, material sources and photos: UL Bivy
Have fun. Making gear can become a full time avocation!
BTW, many thanks to Jamie for posting very detailed instructions on his projects at http://www.lytw8.com. I have referred to them many timesDec 5, 2013 at 8:04 pm #2051368
This is quality information with good detail. I love the open source nature of the MYOG community. Jamie, that is a great web site with a lot of well executed projects. Thank you for sharing your ideas. Andy, thank you for the additional information on your bivy and the link to your write up. My materials for a tarp and bivy should be here Saturday. Can't wait to get started.
Thank you both.Dec 5, 2013 at 10:00 pm #2051404
Aaron SorensenBPL Member
@awsorensenLocale: South of Forester Pass
Just made one today with Impitus 1.1
It actually breathes a lot more than I thought it would (by breath test).
Has a 36" zipper. Not sure of the weight yet.Dec 8, 2013 at 8:51 am #2052027
Jeff McWilliamsBPL Member
These bivies with cuben on the bottom look great!
I haven't sewn any. I am hoping to get started with a Silnylon bottom bivy this winter (to test in the Spring), and if it goes well, perhaps my next bivy will be made with cuben.
Were there special considerations you had to make when sewing the cuben? My understanding is that when making tents/tarps, there are certain design considerations that have to be made so that the cuben does not fail at high stress areas.
Obviously, areas of high tension & stress would not be expected on a bivy, but I was wondering what other issues people run into.Dec 12, 2013 at 4:41 pm #2053722
I just finished the Bivy. Turned out great. I posted pictures of it here
Thank you guys for the helpDec 12, 2013 at 4:54 pm #2053727
Jeff, In this circumstance there was no special consideration taken while sewing cuben. That comes into play when sewing high stress areas such as on a tarp. Different people handle it in different ways. For the tarp that I will be building I plan to do a combination of bonding and sewing.
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