Cuben Fiber Tree Straps?

[dishonor39]

I was wondering if this has been tried or tested by anyone? This seems like such an obvious idea, there has to be some drawback... I was recently reading the thread regarding wider tree straps being required by some state parks. Is cuben fiber tough enough to handle the weight if sewn correctly? Can the abrasion wear be ducked by making 1 layer of the strap have some sort of abrasion resistant coating?

Edit: Maybe Kevlar or some other lightweight abrasion resistant or self repairing material on the one side that would be in contact with the tree, cuben fiber on the other side? Would the weight than start to be equal to that of polypro?

[nothermark]

The first problem is that cuben is not a fiber in the cloth sense. It could be described as two sheets of mylar with a fiber screen laminated between them. The company makes many versions. This will tell you more:

http://en.wikipedia.org/wiki/Cuben_Fiber

BTW, Kevlar is not particularly abrasion resistant. Polyester and Polypropylene do better. Then there is UHMWPE.

Really the answer is probably seat belt webbing but there are other alternatives. If you want to learn there is enough here to get started digging. If you just had a thought the answer is that it is probably not going to be a good choice.

[DemostiX]

To toot your zoot, look into Dyneema climbing slings from many of the major players. They are also called runners.

If you don't think they are expensive enough, that's because you are looking at the 24" or 60cm long ones. Prices scale with length. While they are loops, they are also not wide enough, so you'll be using them in a doubled-wrap configuration.

[dishonor39]

I was just wondering, I use 1" polypro and whoopies. I was just wondering why it hadn't been mentioned, now I see why! Thanks for the answer. I was thinking something 2" wide, half as strong as polypro, and half as thick or less. Thanks for the clarification as to the limitations of the material.

[jbrianb]

A pair of 78 inch 1,500 lb. 1-inch polyester straps weighs 2.8 oz. (That's actually a pair of 72-inch straps with four inch loops). Trim to two 60-inch straps with four-inch loops and it would weigh 2.3 oz.

I don't know the properties of Cuben, but I do know it punctures easily. 2.3 oz. would give you five foot straps, better abrasion resistance, better burn resistance, better strength, lighter weight and less stretch than similar nylon. that's a small weight penalty for the peace of mind, considering Cuben not being a fiber and all, being new, etc... I am going with polyester. When technology proves Cuben is better and time reinforces this, I will make the change.

It is an interesting thread and it made me pull out my calculator! One day, these superfibers will change everything we do (as nylon and poly did!).

[DemostiX]

Cuben is irrelevant to this. It is a dyneema-fiber reinforced thin film. Pick your favorite fiber from which to weave straps. The only ones to consider are those cordage is already made of, since tensile strength is the primary parameter.

[SkyPainter]

Give some consideration to skydiving harness webbing. 1 to 3 inches wide, and takes the opening shock of a 200 lb body falling at over 100 mph!

[DemostiX]

Give some consideration to skydiving harness webbing. 1 to 3 inches wide, and takes the opening shock of a 200 lb body falling at over 100 mph!

Only for a short piece. Maybe for such the stretch that is so objectionable in nylon straps from other sources would not be quickly gone. But, as for climbing ropes and harnesses, elastic stretch is part of the shock absorption.

[Fire-Bug]

What if the straps were made from hybrid cuben fiber, like the material in the bear bag referenced below...

http://lukesultralite.com/content/cr...g-hybrid-cuben
Not sure what the final weight would be on them, but they sound strong enough at first glance. Thoughts everyone?

[nothermark]

What if the straps were made from hybrid cuben fiber, like the material in the bear bag referenced below...

http://lukesultralite.com/content/cr...g-hybrid-cuben
Not sure what the final weight would be on them, but they sound strong enough at first glance. Thoughts everyone?

The basic question is "why add the mylar?". The strength is in the fiber skrim. You could laminate the fiber into a matrix but you still need the fiber. Weaving a high strength fiber into a tape is lighter and possibly better depending on the weave pattern plus it saves the weight of the matrix material.

Cuben and fiberglass laminates are both forms of Fiber Reinforced Plastics. They use a fiber for strength and the embedding plastic for another property. With boat laminates the resin adds stiffness and water resistance. With Cuben the mylar adds flexible water resistance. Hanging straps do not need the added function so a plain fiber bundle is the cheapest, easiest and lightest answer.