Cheap, Light(ish) Cordage

[lysdexia]

I have a dandy new hammock and am wondering how one goes about determining tensile strength of inexpensive twine. I weigh 230 pounds and would like for all of them to remain in the air where I put them.

Suggestions?

[manzana]

That is precisely why I cannot sleep in a hammock. I worry that the ropes at the head of the hamock will break. I would guess that the result would be a broken neck. (I know it is silly)

Apple

[Ramble~On]

Why use twine ? if you don't mind me asking.
If there is a rock climbing store near you look into some one inch tubular webbing.

[Youngblood]

I have a dandy new hammock and am wondering how one goes about determining tensile strength of inexpensive twine. I weigh 230 pounds and would like for all of them to remain in the air where I put them.

Suggestions?

The manufacture usually lists the working load, which is a percentage of the tensile strength. The also should tell you what that percentage is. Most hammockers stay away from nylon because of its stretch characterists. I have been using a 1/4 inch hollow braid polypropylene rope manufactured by Wellington and sold at KMart. It has a recommended working load of 140 lbs and that is derived by taking 15-20% of the New Rope Tensile Strength. You may want something stronger than what I use.

Youngblood

[lysdexia]

Haha! Yep, I think I'm about 100lb over. :-)

I'll look around.

[Pencil Pusher]

Why use twine ? if you don't mind me asking.
If there is a rock climbing store near you look into some one inch tubular webbing.Similarly, you could opt for 3 or 4mm perlon to reduce the bulk.

[pvtmorriscsa]

Howdy All,

Personally I use parachute cord. I swear by it is fact. I use it for bootlaces in all my boots, drawstrings in any garment I make that requires it, and guy lines for my tent.
It is sold in 450lb test or 550lb test. I have never used it for a hammock, (I have set up a hammock), but it might work.
Doesn't seem to be heavy, and it is durable as hell.

[Jaybird]

I have a dandy new hammock and am wondering how one goes about determining tensile strength of inexpensive twine. I weigh 230 pounds and would like for all of them to remain in the air where I put them.
Suggestions?



i'd head to your local outfitter store & buy some 300lb test line!
hehehehehehe :D

[hungryhowie]

I have a dandy new hammock and am wondering how one goes about determining tensile strength of inexpensive twine. I weigh 230 pounds and would like for all of them to remain in the air where I put them.

Suggestions?

Most manufacturers of rope/cord recommend that the working load never
exceed 15% of new rope breaking strength. If dead weight is 230 lbs,
you'd want a rope with a breaking strength of ~1500 lbs.

Inexpensive twine is probably not what you want to trust your safety on. I'd go with 1" polyester webbing, or 3-4mm spectra rope.

Remember, a knot halves the breaking strength of any rope, and the stress generated from falling even a modest amount adds up quickly in poundforce/newtons. Ropes should be replaced periodically as they begin to show signs of wear. For avid hammockers, that could be anywhere from every three months (of hard use) to several years.

-Howie

[BeaverTrapper]

I agree with the Spectra cord. I just like the way it 'handles'. I weigh 220, and prefer 4 or 5mm; not so much for the weight limit, but I find that a 5mm cord is easier to tie and untie, than a tiny 2 or 3 mm cord. I find that ten feet on each end of the hammock is enough, although if you are in an area with big trees, ten feet ain't much.

As far as cord goes, the absolute best cord I have ever found for minor use is tarred nylon twine that is sold for use as trotlines. You can find it in the fishing section at Walmart. It's cheap, comes in various sizes, is nylon, and is coated with tar which makes it EXTREMELY weather resistant (ie: will never wear out), and the tar makes it 'knot' well. It is so long lasting that the law in Alabama is that all trot lines must have ends made of cotton line, as the nylon stuff will never degrade and allow an abandoned line to fall to the bottom of the river.

I buy it mailorder by the pound, and keep a crap load of it wound around my hiking stick. Makes a good grip and I never run out of string. :)

[Frosty]

I agree with the Spectra cord.
I buy it mailorder by the pound, and keep a crap load of it wound around my hiking stick. Makes a good grip and I never run out of string. :)Is this what someone else referrred to as parachute cord? Where do you order it from?

[Pencil Pusher]

Spectra, as I understand it, is comprised of kevlar-like strands. Extremely strong and nearly just as expensive. I think it runs at $1/ft. It's a bit more stiff than rope or twine. You can probably get it from REI.com or Google 'spectra' or 'climbing gear'.

[Frosty]

Spectra, as I understand it, is comprised of kevlar-like strands. Extremely strong and nearly just as expensive. I think it runs at $1/ft. It's a bit more stiff than rope or twine. You can probably get it from REI.com or Google 'spectra' or 'climbing gear'.Thanks for the info on kevlar. I wasn't aware that's what it was made of.

I already did google. Didn't see REI, but there were several places to get it, none of which I was familiar with. That's why I asked beavertrapper where he ordered his from. I was also curious as to spectra cord is what someone else referred to as parachute cord.

[TedB]

Somebody already mentioned working strength is normally a small fraction of tensile strength. The tensile strength measurement is normally done under laboratory conditions with a rope in perfect condition, with no knots or sharp bends. That is why it is not a real world number.

I would also add just comparing your weight to working strength is also a dangerous practice. I learned this through personal experience. As a kid, I had a zip line setup in the backyard. A rope strung between two trees, and a pulley as the slider. If my memory is correct, the working strength was 150 pounds and I weighed about half that. Any way, once I recovered a little from the extreme pain, I was shocked that it would break.

A hammock has a similar geometry to the zip line, where the tension in the rope is not in the vertical direction. This places enormous load on the rope, many times your body weight. A book on rock climbing anchors or a book on physics can provide more details on exactly how much force it produces. A real world example, is to put some weight in your hammock, tie one end to a tree, and hold on to the other end. Anyway, I hope you learn from my example and that you do not cut corners.

[sgtjinx]

Howdy All,

Personally I use parachute cord. I swear by it is fact. I use it for bootlaces in all my boots, drawstrings in any garment I make that requires it, and guy lines for my tent.
It is sold in 450lb test or 550lb test. I have never used it for a hammock, (I have set up a hammock), but it might work.
Doesn't seem to be heavy, and it is durable as hell.
He's right, I would also use Paracute cord. (550) It is the best cord you can buy. The 550 will not rot or dry out, and comes in black,green and white.

I'm about 250 pounds and I am going to use it with my hammock.:cool:

Sgt Jinx

[Connie]

ohh, this is truly pricey stuff ..

http://www.backpackinglight.com/cgi-bin/backpackinglight/aircore_pro_ursa_bear_bag_hanging_rope.html

http://www.backpackinglight.com/cgi-bin/backpackinglight/aircore_plus_spectra_cord.html

looks like the same product.

They did have three other diameters, on that website. Hmm..



Connie

[Pencil Pusher]

Man, this is too much thinking for when you want to just crash out...

[ocourse]

http://ecom.citystar.com/hang-em-high/ushop/index.cgi?ID=HLQUTZ&task=show&cat=LINE

[steve hiker]

ohh, this is truly pricey stuff ..
You got that right @ $1 a foot. What's it made out of, spider cob? I don't see why home depot yellow twine won't do, it's plenty strong and costs nothing.

[titanium_hiker]

as per http://www.imrisk.com (flyfisher/risk's site) I use webbing. packs down pretty small, light(ish) and only cost me 1.50 bs (8 bs to the US dollar so that's roughly 16cents) a metre. And it's friendly to the trees and strong. Very easy knot to tie that doesn't slip.

[creekfisher]

I have been buying cordage from the following website for several years. They have the best selection and prices that I have found.

They have small diameter, low-stretch lines:
http://www.apsltd.com/Tree/d3000/e852.asp

They have single braid made from Dyneema fiber with bright yellow Samthane urethane coating:
http://www.apsltd.com/Tree/d3000/e867.asp

They have nice shock cord:
http://www.apsltd.com/Tree/d3000/e876.asp

[flyfisher]

Just my $.02:

Hammock hanging straps/rope need a lot more strength than a person's weight. It has to do with geometry and trigonometry and vectors, which is a little complicated. I agree with the rule of thumb I originally read in Ed Speer's book: at least 600 pounds of working strength.

If it stretches it drives me crazy. So I never use nylon. Spectra and the two polys are pretty good materials.

I have experimented with thin spectra cords. I find them much harder to use (since they require tree huggers) than 1 inch webbing. The weight advantage is not great enough and I have come back to 1 inch webbing again.

Personally, I would not use rope or cord of any sort without tree huggers. The risk to the tree is real and there can be a problem with the rope rolling down the tree if tree huggers are not used.

I would certainly never use parachute cord. It is not strong enough. It catches on every piece of bark, fraying terribly, and knots tied in parachute cord are *very* hard to untie. I don't even use parachute cord for my tarp for all the above reasons. Instead I use thin spectra cord that is easy to untie even when wet.

Here is a review I wrote on the tarp cord I use:

http://tinyurl.com/5lnwx

For hammock hanging straps I use one of these four:

1) Ed Speer's polyester webbing (not polypropyline) It is not listed on his site, but is often available if you call:

http://www.speerhammocks.com/Products/PRODUCTLINK2.htm

2) Speer's Polypropyline webbing... at the above site

3) http://www.owfinc.com/

Polypro 1" strap
WP1H black .34/yd

4) http://www.questoutfitters.com/

Polypro 1" strap 10 yards Breaking strength 600#
#1023 .45/yd

[The Hammocker]

People, USE PARACHUTE CORD!!!!!!!:jump

[flyfisher]

Howdy All,

Personally I use parachute cord. I swear by it is fact. I use it for bootlaces in all my boots, drawstrings in any garment I make that requires it, and guy lines for my tent.
It is sold in 450lb test or 550lb test. I have never used it for a hammock, (I have set up a hammock), but it might work.
Doesn't seem to be heavy, and it is durable as hell.
I sure would not recommend parachute cord as the cord to hang a hammock from. Most parachute cord is not designed for these loads.

Because of the angles and vectors and some geometry, the cords need to be somewhere near 600 pounds of strength for me to feel comfortable. (I weigh 200 pounds)

Avoiding nylon is a good idea because of its stretch properties. Polypropyline and Polyester are great materials. I use 1 inch webbing most of the time. It is strong enough and does not roll down a tree.

I have used spectra cords like those used in the Hennessey Hammock, with tree hugging straps, but the weight and bulk savings are not great enough for me to put up with the difficulty I have using the tree huggers. Setting up a hammock with tree huggers takes about twice as long as using the webbing alone. (Five minutes instead of two.)