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Joe L
(heyyou) - MLife

Locale: Cutting brush off of the Arizona Tr
Q: Cuben tree straps for hammocks on 12/26/2010 20:15:53 MST Print View

For non-hammock users, tree straps are webbing (inch or wider) with end loops that protect the tree's bark instead of using thin rope that could gouge the bark.

Why has no one started making UL tree straps from belts of high bias Cuben fabric?

Adequate strength would be from using several inches of width of the stronger, high bias Cuben. Is it the liability, the lack of a market for $$$ SUL hangers (hammock users), bonding strength for the loops, or tear strength of the loops with tiny Amsteel cords run into them? When you have lightened all of the other parts of a hammock system, often the tree straps are the heaviest remaining item.

Would silicon tubing in the end loops solve the abrasion problem from the 1/8" whoopies? If the bonding surface was several inches both directions, wouldn't that be strong enough?

Yes, I could have posted these questions at HF.

Greg Mihalik
(greg23) - M

Locale: Colorado
Re: Q: Cuben tree straps for hammocks on 12/26/2010 21:51:31 MST Print View

Cuben hammocks failed catastrophically near the gathered ends. It wasn't for lack of desire or trying. Just a function of the material.

Look Here.

I think you'd be facing the same issues with tree straps.

Edited by greg23 on 12/26/2010 21:52:10 MST.

Ken Thompson
(kthompson) - MLife
Re: Re: Q: Cuben tree straps for hammocks on 12/26/2010 22:27:39 MST Print View

Plus the straps are the sacrificial part of the suspension. Too nasty with sap or all scraped up, replace. Webbing is cheap.

Michael Davis
(mad777) - F

Locale: South Florida
Re: Q: Cuben tree straps for hammocks on 12/27/2010 20:55:01 MST Print View

Tree straps endure a lot of abrasion. I'm no expert in cuben but I wouldn't think they would last long enough to be worthwhile. Plus, I would have nightmares involving catastrophic failures on my way to the ground :(

Colin Krusor
(ckrusor) - M

Locale: Northwest US
Cuben tree straps on 12/27/2010 21:11:12 MST Print View

I agree with some of the others who have concerns about abrasion. Cuben (even products using the heavier 0.18 film) does not tolerate abrasion well.

Also, I don't understand why you would choose a high-bias style. In a tree strap, you only have one load path. A high bias style would just have more fibers in directions that are not under tension. It would be extra weight and extra cost that does nothing for the strength of the strap.

Cuben would only be practical for this application if you used a very heavy, cardstock-like style with 0.5 mil Tedlar film. Steve Evans has used Cuben products in that category for snowshoes. You could contact him to see if he'd be willing to sell you a ribbon of it, if he still has any.

Bill Fornshell
(bfornshell) - MLife

Locale: Southern Texas
Re: Cuben tree straps on 12/28/2010 11:11:18 MST Print View

I posted this on my Cuben Hammock Thread at the Hammock Forums on 03-31-2009:


Cuben Hammock

===========

I had never gotten around to making a set of tree huggers for my Cuben Hammock. I have some very heavy Cuben Fiber that is 5.88 ounces per sq yard and very strong. I decide to see if it would work for tree huggers. I cut a piece 3 inches wide and about 10 feet long. I doubled and sewed the material making it 1.5 inches wide. Then sewed loops on each end. I cut the tree huggers for a finished length of 84 inches. I think this is longer than they need to be but may leave then as is.

I have been in and out of my Hammock several times and the Cuben Tree Huggers seems to be working OK.

The weight of one of the tree huggers is 1.35 ounces.

===========

When their was a lot of talk about "Amsteel Blue" cord I called the company and asked about it. They didn't have any in Blue but did have 1/8" in Light Gray. I bought a bunch.

When I weighed a one foot piece it came out to about 2.25 grams per foot. I cut two 12 foot pieces and attached it to my Cuben Hammock. I then tied the Hammock to tress in my back yard and got in. It seems to be working just fine. The Hammock is hanging as I type this but the Mosquitoes were getting bad and I came in to put on some long pants and a long sleeve shirt.

The new total weight of my Cuben Fiber Hammock - Hanging - is 5.51 ounces.

============

Since I did all of this I cut a new piece of the heavy Cuben and used it with one layer. This would cut the weight in half so the pair would weight about 1.35 ounces. I have only tested the one layer straps a few times.










Edited by bfornshell on 12/28/2010 21:46:23 MST.

Joe L
(heyyou) - MLife

Locale: Cutting brush off of the Arizona Tr
comment on 12/28/2010 20:40:53 MST Print View

Thank you Bill for sharing your designs and your extensive knowledge. I'm not suprised that you were years ahead of my question.

Colin, I hadn't thought about the direction of the forces, I was only thinking of the additional strength of the high bias. Thank you for showing me what I had missed.

My opinion is abrasion from tree bark would only be on the film, not on the Dyneema threads.

Colin Krusor
(ckrusor) - M

Locale: Northwest US
Cuben abrasion on 12/29/2010 11:03:19 MST Print View

Joe,

I think you're right that the abrasion from tree bark would be sustained by the film of a piece of cuben, not the dyneema fibers. This is the reason that I think it would be advantageous to use a cuben product with very thick film (like the kind described by Bill).

We could test the importance of abrasion by loading two similar cuben straps to failure around a knobby tree, one directly against the bark and one over a thin layer of foam. I'd wager that the foam protected piece would fare better, and that the difference between the pieces would be relatively greater than for two pieces of nylon webbing.

Adding a thin strip of Evazote or some other light foam on the tree side of the strip might be a good way to go, actually.

Steven Evans
(Steve_Evans) - MLife

Locale: Canada
Re: Re: Cuben tree straps on 12/29/2010 17:20:08 MST Print View

I've got some of the thick cuben left but not sure how long it is. It weighs roughly 4 oz/yd^2 and it is totally bomber. I went through 2 pairs of scissors cutting the pattern for my snowshoes. Let me know if you want some strips.

Tim Marshall
(MarshLaw303) - MLife

Locale: Minnesota
Re: Re: Re: Cuben tree straps on 12/29/2010 18:18:40 MST Print View

Bill,

You could shave some more weight from your hammock by switching from 1/8" amsteel to 1.8mm dynaglide. it has 1000# BS and is good for users upto 200#(i've heard 300# but arrowhead rates it at 2) not trying to hyjack, but i know Bill is even crazier than me about shaving weight so i thought i'd throw that out there.

dynaglide found here
http://www.baileysonline.com/search.asp?skw=dynaglide&PageNo=1&x=0&y=0

-Tim

te - wa
(mikeinfhaz) - F

Locale: Phoenix
Re: Cuben tree straps on 12/29/2010 20:29:31 MST Print View

you guys got me to thinking, since i never weighed my amsteel tree 'straps' until now..
im using 7/64 amsteel blue (in gray!) in 5' sections. both of them weigh .72 oz total.

as aformentioned tree damage, i simply put a few sticks in between the tree straps and the string.
using a toggle from a whoopie/amsteel coupling sometimes is a pain to adjust moreso than whoopie/webbing setup but i can live with the 3oz weight savings.

do you think this could be a solution for you instead of cuben?
mike

Edited by mikeinfhaz on 12/29/2010 20:40:38 MST.