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Cuben Fiber Hammock
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Bill Fornshell
(bfornshell) - MLife

Locale: Southern Texas
Cuben Fiber Hammock on 03/06/2007 15:23:56 MST Print View

Cuben Fiber Hammock - 6 March 2007

Ever since I bought my first yard of Cuben Fiber I have thought about trying it for a Hammock. Since it now looks like half or more of my AT Hike this year will be during the warm season and maybe also the rainy season I have decided to find a SUL way to move off the ground and into a Hammock.

In the past it seemed to me that sleeping in a SUL Bivy and using a light sleeping pad of some kind along with a Poncho / Tarp over head was the lightest way to go. I have several light Hammocks made out of silk but they are still in the 12 to 14 ounce range and they still need a tarp of some kind for rainy nights. Using Cuben Fiber for both the Hammock and the Tarp I should be able to get real close to the weight of a SUL ground set-up. I am hoping to use the Hammock without a sleeping pad so that will save me 5 to 10 ounces. If I do have to use a pad it will still be smaller for the Hammock than if I was on the ground.

I don't know where the fine line will fall when it comes to total weight between the a comfortable and SUL ground set-up vs a SUL Hammock set-up but I expect I will find out.

This is Cuben Fiber Hammock ver. 1.0. The Cuben Fiber I am using is just a little heavier than what I like. It weighs about 0.47 ounce per sq yard and is 50.5" wide by 126" long. The Cuben Fiber for the Hammock weighs a total of 2.36 ounces. The fiber density of this material is very high so it should be more than strong enough. The weak point may be the stress on the knot that holds the hammock in the webbing. Time will answer that question.

The Black webbing is the kind Ed Speer Hammocks uses on his line of Hammocks and will sell the webbing to anyone that wants to make their own Hammock. The small aluminum fittings are some I made to connect a short piece of the black webbing to the Hammock and to connect the white cord. The black webbing and small aluminum fittings weigh 0.85 ounces. The white cord is a 3/32" Spectra core low stretch something from West Marine and will go from the aluminum fitting to the tree. I will use tree huggers and the white cord will attach to the tree huggers.

I am going to try and take a timed picture with me in the Hammock after I have used it awhile. I don't want to run and jump into this one till I have a few hours laying in it.

The knot holds the Hammock in the webbing.

Weight to date:
Cuben Fiber for the Hammock body - 2.36 ounces
The two pieces of black webbing and two small aluminum fittings - 0.85 ounces
The white cord from the black webbing to the tree - 16 foot at 0.05 ounces per foot = 0.85 ounces
Tree Huggers - Speer Webbing - 2.89 ounces a pair

Total Weight Hanging for ver 1.0 = 6.95 ounces

I will try and nap in this hammock for a while everyday to test its durability.

Eric Eaton
(ericeaton) - F
Re: Cuben Fiber Hammock on 03/06/2007 16:37:56 MST Print View

Oh my Bill, you never cease to amaze.
Thank you for inspiring us by sharing your creativity and passion for THE lightest in designs and materials. Also, your workmanship is something to aspire towards.
Thanx again,

Eric Noble
(ericnoble) - MLife

Locale: Colorado Rockies
Re: Cuben Fiber Hammock on 03/06/2007 17:25:09 MST Print View

Bill, I can't wait to hear about your experiences with this. I'm currently looking for ways to lighten my Hennessy hammock. Your design seems clear to me except for the aluminum fittings. I'm probably missing something real simple. It wouldn't be the first time. Why not tie directly to the webbing and skip the fittings or tie directly to the fabric? Also, how did you fold the fabric, is it an accordion fold?

Miles Barger
(milesbarger) - F - M

Locale: West Virginia
Breathability? on 03/06/2007 18:32:55 MST Print View

This looks very interesting. Is breathability not a concern? Or would the hammock be part of a VB system?

Bill Fornshell
(bfornshell) - MLife

Locale: Southern Texas
Cuben Fiber Hammock on 03/06/2007 20:15:23 MST Print View

eric e,

The nice thing about a site like this is the many folks that post here. I am inspired also by many of them. I think we feed upon each others accomblishments. I could list many that inspire me. One is Alec and the winter race he ran not long ago. I would love to just get into something like that even if it took me forever to finish. The photos that are posted here are amazing. So many others sharing what they do best inspiring each of us to try something new or push ourselves to the next higher level.

Eric N,

Why didn't you asked me that question before I made those fittings. To really answer your question - I thought I needed a smoother transition between the webbing and the cord. I was a little afraid the cord might saw through the webbing over time so the small aluminum fittings eliminate that possibility. It was a preventive measure on my part. I also have a small experience factor that said don't tie the cord to the Cuben Fiber.

I did an according fold on the Hammock fabric. I have what has to be the only Speer Silk Hammock ever made by Ed. I sent him the silk back in 2003 and he turned it into a really great Speer Silk Hammock. It weighs 14 ounces complete with a silk mesh bug net. I also have his book.

Miles B,

Breathability is not a real concern for me. You might say that any negative effect will just be part of the trade-off for the very light weight advantage of the Cuben Fiber. At the same time any blowing rain getting under the Hammock will not wet-out the Hammock bottom and will help my bottom stay dry. Using the Hammock in all types of weather will prove me right, wrong or somewhere in between.

Part of a VB system - sounds good to me.

Edited by bfornshell on 03/06/2007 20:17:50 MST.

Aaron Sorensen
(awsorensen) - MLife

Locale: South of Forester Pass
Re: Cuben Fiber Hammock on 03/06/2007 21:51:11 MST Print View

Hey Bill,
Was there any problems with the total density of the silk hammock?

I would think it would sag on the high weight area's
I would love to see this work for you.

A picture with you in the hammock and in your all Cuben bag would be a sight.

I'm beginning to think that your next project is going to include some wings that will allow you to just fly through your hike. Maybe a 1 pound air-balloon so you’ll just have to tether your bag to it and have it float behind you.

All jokes aside, that is one impressive hammock.

Chris Jackson
(chris_jackson) - F
hammocks and quilts on 03/06/2007 22:06:40 MST Print View

Bill, at the risk of serious thread drift, have you had a chance to test your synthetic quilt or insulated bivy at lower temperatures this winter?

I'd be interested to know how much insulation/yd you'd want to sleep comfortably at 32F with just the quilt and a light t-shirt. I'm skeptical about the manufacturers' clo values, especially after stuffing and unstuffing a few times.

Paul Wozniak

Locale: Midwest
Re: Cuben Fiber Hammock on 03/07/2007 07:03:41 MST Print View


What a fantastic project! I've just sewn my first hammock, a Speer kit, and am excited by your experiment. Conventional wisdom says you will have to solve two problems:

- Cold bottom; I believe you will "cold out" in temps in the upper 60's, a simple 1/8" pad could take you into the upper 50's. Does VB change the equation? How low can you go?

How much of an issue is condensation in various conditions; warm/cold, dry/wet? How much do you have to put up with, yet still find a reasonable trade off?

I know it's early for these answers but you've got my heart rate up with this. So I'm begging, please continue with your reports on this one. And thanks for once again pushing the envelope.

Bill Fornshell
(bfornshell) - MLife

Locale: Southern Texas
Cuben Fiber Hammock on 03/07/2007 11:35:58 MST Print View

I was able to take a few pictures of me in the new Cuben Fiber Hammock this morning. I have also added a few extra pictures with a little more detail.

12 ounce Coke can next to he Cuben Fiber hammock.

Holding the Hammock open.

Racing the 10 second timer on my camera.

There was nothing wrong with my Speer Silk Hammock except it weighs 14 ounces. Ed added 17 foot of velcro for the bug net and used longer tree straps than I would have. This all added weight and I wanted a SUL+ Hammock.

When I need to stay warmer in my Hammock I will go to one of my light quilts / Sleeping Bags. The one layer of Climashield Combat inside my Bivy is good down to about 40 degrees (F). The two layer Climashield Combat sleeping bag has been used down to 26 degrees (F) and will go lower. At lower temperatures a thicker sleeping pad is necessary.

I agree that the bottom of a hammock gets cold and I have some GG 1/8" - 1/4" sleeping pads to play with. I will start wearing my RBH NTS VB shirt and pants as it gets cooler but need to do some testing to see when I need to start with them. With the VB shirt and pants condensation should be no problem. I have never worried much about condensation. Most condensation can be traced to "pilot error".

I have a all Down Hammock set-up that will take me down to "0" degrees. After I built it I didn't use it as I can sleep "lighter" at that temperature on the ground.

Gene .

Locale: New England
Bug & rain protection? on 03/07/2007 12:08:19 MST Print View

Ok, now for the bug protection Bill. What's your rainfly going to be?; your kilt or poncho?

Bill Fornshell
(bfornshell) - MLife

Locale: Southern Texas
Cuben Fiber Hammock on 03/07/2007 12:31:20 MST Print View

Hi Gene,
I am making a new Cuben Fiber Tarp that will be somewhere around 11 foot long by about 8 foot wide. The final shape will be inside those dimensions. I have the Hammock hanging now and will take some measurements later and come up with the final size. The Tarp weight should be around 5 ounces.

The bug net will be made out of some of my very light silk mesh.

Vick Hines
(vickrhines) - F

Locale: Central Texas
Re: Cuben Fiber Hammock on 03/07/2007 14:14:46 MST Print View

I've been happy with a 8.5X5 foot cape/tarp for my hammock and groundling use. Set up on the ground in a half pyramid, it is very weather worthy, and 8 feet is about all anyone needs for the ridge line over a hammock. Longer than that and you tend to run into the trees. Maybe you can save some ounces and have rain gear, too. Consider a Cuben cape/tarp.

Have you tried your hammock with a static line like HH uses to get consistent hangs every time?

Edited by vickrhines on 03/07/2007 14:16:27 MST.

Bill Fornshell
(bfornshell) - MLife

Locale: Southern Texas
Cuben Fiber Hammock on 03/07/2007 15:08:34 MST Print View

I have never been up close to a HH. I have no idea what you are talking about.

As for the tarp I have two sort of big ones that I will set-up over the new hammock and tweak the size downward as much as I can.

I also have the storm cap / think something like a cape that I made as a prototype for the Alphamid I was working on. That or something like it made big enough could be used as both a tarp for the Hammock and as a Poncho / Cape for rain. That would save the weight of stand alone rain gear. I am going to dig out the Storm Cap and hang it over the hammock and see what the size looks like as it now is.

Edited by bfornshell on 03/07/2007 15:29:07 MST.

Bill Fornshell
(bfornshell) - MLife

Locale: Southern Texas
Cuben Fiber Hammock on 03/07/2007 17:15:07 MST Print View

Well I hung the Storm Cap from my Alphamid over my new Cuben Fiber Hammock. The shape might work but this one is way to small. I like the "wedge" sort of shape and might make a larger one out of some scrape Wal Mart material and see how I like it. I don't want a tarp that is to small to keep me dry in a heavy blowing rain. I don't want to be forced into a Shelter in a heavy rain because I made my tarp to small. I am not into "light" at any cost. My big Moss tarp weighs 20 ounces, my lighter Mac Cat large weighs about 16 ounces and a Cuben Fiber Tarp big enough to keep me high and dry should still be under 6 ounces or so.

Gene .

Locale: New England
Re: Cuben Fiber Hammock on 03/08/2007 13:44:17 MST Print View

Bill, You look well, which in of itself is a great thing; keep at it! I don't recieve PMs from here since I'm not a member, but you can PM me over at the other place.

I'm wondering if you've ever done any material testing, by leaving a bunch of scraps of the different types of fabrics outside in the weather(ie, Sun, wind, rain,etc) to see how they'll fare long term? Cuben comes to mind, and also the stretch factor of Cuben or lack thereof?


Royal Magnell
(BlueMan) - F

Locale: Northern CA
Quilt Temp ratings on 03/08/2007 18:44:49 MST Print View

You mentioned that your sleeping bag with two layers of Climasheild keeps you warm to 28*. I about to start sew a quilt out of Climashield XP and I'll trying to decide if I should use two or three layers of the insulation. I'm worried that three layer will be to bulky but on the other hand I'll also worried that two layers won't keep me warm in sub freezing weather..what do you think? Do you sleep warm? (I'm looking for a comparison for how warm two layer will keep me)
I'm going to use silk for the shell and liner and make a bivy to protect the quilt. Thanks so much!


Aaron Sorensen
(awsorensen) - MLife

Locale: South of Forester Pass
Re: Quilt Temp ratings on 03/08/2007 19:21:57 MST Print View

Mr. Magnell,
Welcome to the board.
If your 1st post is asking Bill a question, you're definitely on the right track.

Why don't you use the 3 layers to cover just your torso and 2 layers for the rest?

When you're full covered in a sleeping bag you really don't need that much insulation if your feet, torso, and head are warm.

It also depends on how much clothing you are going to wear to sleep. If your well insulated already, you could get away with 1 layer and keep warm. With a single silk or light weight layer, I would go with what I recommended, 2 & 3 on torso.

Bill Fornshell
(bfornshell) - MLife

Locale: Southern Texas
Quilt Temp ratings on 03/08/2007 19:42:51 MST Print View

Are you making a sleeping bag or a quilt? Or are you putting the quilt inside the Bivy and hoping to get some of the benefits of a closed in sleeping bag? That idea loses its effectiveness as the temperature drops and a good sleeping pad is more important to keep the cold from the ground from getting to you. I have a Down Air Mattress that is almost mandatory for me when it gets much below 32 degrees (F).

If you got your Climashield XP from Thru-Hiker it is listed at 2.5 ounce a sq yard. The Climashield Combat I used is listed at 2.0 ounce per sq yard. Your two layers of XP will be warmer than my two layers of Combat. Your two layers of 2.5 gives you a total of 5 ounces per sq yard vs mine at 4 ounces per sq yard. The math says you should be 20% warmer all things being equal. Make sure you leave a good seam allowance so you don't compress the insulation any more than necessary when you sew it to the silk. Sewing only the edges of the insulation to the silk should be all that is necessary.

Note: Aaron's idea for three layers in certain places is a good one.

I don't think I am a cold sleeper but I do wear something like my RBH NST VB shirt, pants and socks when it is colder. At other times I wear my Patagonia #2 wool zip - hoody, #2 wool bottoms, socks, a wool cap and light gloves.

Try and do some "back yard" testing at the lowest temperatures you think you might sleep out in if possible. Wear the cloths you will have with you for your hike and if you are cold put all the cloths you expect to carry on and see if that is enough to keep you warm. If that doesn't work try a different combination of clothing till you are warm enough.

Vick Hines
(vickrhines) - F

Locale: Central Texas
Re: Cuben Fiber Hammock on 03/08/2007 20:33:11 MST Print View

One festure of the Hennessy Hammock that gets overlooked is a line that connects the ends of the hammock, but is shorter than the hammock itself. Most folks thing this line serves only to support the mosquito net. in fact, it gives the hammock the proper "sag" no matter how the support lines are positioned - except if they are very saggy. What you get is consistent set-up.

Your tent - the one with the cap on it - looks a lot like a half-pyramid set up with a cape/tarp - probably cut a little differently, but not much. Does it have a floor? If not, maybe it would work as your hammock fly if the dimensions are close to 8 or 8.5 x 5.

Royal Magnell
(BlueMan) - F

Locale: Northern CA
Re: Quilt Temp ratings on 03/08/2007 20:56:14 MST Print View


Yes this is my second post and yeh Bill seems to be quite the authority!
I'm making a quilt, and yes I was thinking I would use it in conjunction with a bivy. My reason for wanting to do this is
I figued that the silk would not be wind proof and I've also heard that a quilt can feel quite drafty at temps below freezing. I was figureing on elimanating these problems be using a bivy..good idea..bad idea? Otherwise I think I'd make the outer shell of the quilt out of Momentum. I use a 3/4 length ridgerest and it seems to do the job though its not real soft but hey I'm young and it was cheap! Maybe I'll wind up using 3 layers in some places adn two in others as suggusted..or I might just sew a insulated jacket and sleep in it..

All I've used before is my NF 20* down bag, it has 2.5inchs of loft on top and its kept me warm down to 20* in the Sierras (during my recent thruhike of the JMT..way fun!)with plenty of layers on.

What kind of neeble do you use on silk by the way?