Dyneema for Hammocks

[Crafty]

Hello,
I have been thinking about Dyneema for hammocks, problem is that I havn't used it much before and would like some other opinions aswell.

 

[lostagain]

Crafty,

I've just started to use some 2mm in black of this stuff for tarp guy lines. Its a tough as old boots. I would dare say that if I used two x 2mm lines on each end of my hammock it would hold. I would still prefer the security of the straps though.

I haven't tried any of the thicker diameter dyneema but I'm sure it would be ok if you got the correct size. You'd still have to use something wider on the tree to prevent damage by the thin dyneema.

 

[welshwhit]

Hi mate,

I've used 2 240cm climbing slings made out of Dynema to hang my hammock, no worries with it!

I'd go for something a bit wider than 2mm for the psychological edge!

Drew

 

[wentworth]

Dyneema rope? I've used 3mm along with tree huggers. Just check the rating. And spectra doesn't hold regular knots as well as some other rope. Apparently the force exerted on a hammock strap is far greater than just the weight of the person in it, for reasons I personally don't understand...
Or did you mean dyneema fabric for the hammock body?

 

[Graham_S]

I use 8mm spectra for my hammock ropes.
I braided a loop in each end to go around the tree, and tie off the free ends to karabiners attached to the hammock.
I've had no problems whatsoever with this setup.

 

[Satyr]

I just posted and then hit the back button - and now have to type all over again; technology mocks me eternally!

Dyneema, Spectra and Certan are all trade name for high-modulus polyethylene (HMPT) and gram for gram it is about 10 times stronger than steel. It has great tensile strength so makes brilliant slings or webbing but is very "slippy" so ropes made out of it suffer when it comes to tying knots. This is even worse when they are wet as the surface friction can drop by as much as 50%. HMPT has very little stretch when under load, less than 2% at half it's breaking limit.

In short - yes Dyneema is good for hammocks; just get some long enough to leave long tails after your knots (this applies for flat webbing or rope) and tie stoppers on the end and really chose your knots well or you will wake up on the ground.

 

[Graham_S]

I use a falconers knot on my spectra ropes and it doesn't slip, even when wet.
And it should be pointed out (before anyone else says it) that I'm quite a chunky monkey so it's under a reasonable load!

 

[Shewie]

Dyneema and Spectra are the mutts nuts when it comes to cordage you can rely on, but isn't there an argument for using tapes on trees rather than thin cord ?

Tree huggers or a sling of some sort would help to prevent damage to the bark, but then you've probably thought about that anyway :thinkerg:

 

[C_Claycomb]

Dyneema etc only generally refers to the core of the rope, not the sheath, which is what determines how well knots grip. All the braided core lines that I have seen have something like polyester sheathing. The only problem is that the core and sheath don't always melt and stick to one another as well as all nylon or all polyester combinations.

I weigh about 170lb and have had no problem with 3mm line on my Hennessey. Always use straps around the tree. Some mature bark is pretty resistant to lines, but even 8mm cord will damage younger trees.

There is a thread somewhere on here showing my mod to my hammock, new ridgeline and support lines.

 

[EarlyRiser]

I know this is going off at a slight tangent but are prusiks with dyneema on dyneema prone to slip or is it just a case of a few extra turns to compensate for the lower friction?

Tom

 

[Ratbag]

<snip>
In short - yes Dyneema is good for hammocks; just get some long enough to leave long tails after your knots (this applies for flat webbing or rope) and tie stoppers on the end and really chose your knots well or you will wake up on the ground.

Good summary. But why bother with Spectra/Dyneema at all? Climbers like it because it's insanely strong for a given weight, but most bushcrafters don't have the same concerns about weight. Also, you don't want to use 3mm Spectra to suspend your hammock because you'll end up cheese-wiring the tree in half! And you won't trust it anyway...

If you would choose an 8mm Spectra cord to suspend your hammock you might as well use 8mm normal climbing accessory cord - it's more than strong enough, it's waaaay cheaper and it's more predictable when you tie knots. Same comments apply for Spectra or Dyneema tape vs normal climbing tape.

Just my opinion, of course

Rat

 

[Satyr]

Tom

Most climbing ropes are not made completely out of Dyneema as they would cost a fortune and would not pass some of the EN standards. Part of a ropes specification is that the rope must be able to mitigate the impact force for a factor 0.3 fall to 5kN or below - this is for a static rope and not dynamic rock climbing lines which are designed to take out even more impact force.

Climbing ropes that are made with Dyneema usually have a Dyneema core to give strenght and a nylon protective sheath (kernmantle ropes) - this is what the prussic will be bighting into.

Lots of accessory cord is made out of Dyneema these days to get the strength rating for thin lines. Best practice is to do a 3 wrap prussic using prussic cord that is 2mm narrower than your working line - but you have to experiment to find the best number of wraps for the rope you are using (if it wont bite at the ground then take it off and try it with an extra wrap)

 

[Satyr]

Rat,

My sentiments exactly! HMPT has it's place and it is really best suited to industrial access and rescue or sport climbing - in all of which you are dealing with life support. For everything else it is a bit of overkill

 

[EarlyRiser]

Satyr

Thanks for the info.

My question about prusiks was more to do with tensioning tarps than climbing.

Cheers

Tom

 

[welshwhit]

I agree with the thin cord comment cutting into the trees isn't what we're about really.

In my case I had spare climbing slings and I have used them in place of tape.

 

[Scots_Charles_River]

Just wrap the spectra around the tree two or three times, that will spread the load.

Less damage than the monthly storms.

It is seriously strong and packs down a lot smaller than tape.

Nick

 

[wentworth]

As stated in my previous post, 3mm spectra is used in conjunction with tree huggers. These are 1m nylon/ polyester or polypropylene straps that wrap round the tree. You then tie the spectra to these straps.

No rope should be used directly on the tree, unless it is the hollow core rope that flattens out like webbing. Rope leaves marks on trees, if word gets round that hammockers are injuring trees, it leads to hammock camping being banned in certain areas.

Easy to avoid this.

 

[C_Claycomb]

Just wrap the spectra around the tree two or three times, that will spread the load.

Less damage than the monthly storms.

It is seriously strong and packs down a lot smaller than tape.

Nick

Two or three turns might work for you, but I have seen it mark young ash trees when done with 6mm rope. Monthly storms don't tend to crush the bark in a ring around the trunk. Using poly or nylon 1 inch webbing is so easy I don't see why one should do anything else. You don't even need to have loops sewn on the end of the webbing, there are plenty of knots that will join a line to it without problems. BUT, if all you hang to is mature Scots Pine and ancient oaks, you can probably get away with the rope, but it won't work acceptably for all situations.

For cords for hammock hanging you find more of interest in a sailing shop that you do in a climbing shop.

Reducing weight and bulk may not be everyone's cup of tea, but it is a valid pursuit and undoubtedly makes life easier when you are hiking in the back country. Sure, you aren't going to save a huge amount of weight, but every little helps. By my changing to thinner hammock line I have been able to hang from supports which are further appart, without needing to use longer line, and have cut down on bulk too

 

[Gailainne]

Satyr

Thanks for the info.

My question about prusiks was more to do with tensioning tarps than climbing.

Cheers

Tom

Prusiks only work well where the main rope is significantly thicker than the secondary, see here, however saying that I use 3mm racing dyneema as my ridge line and I tension my tarp off it using bungee loops prusiked to it, works fine.

The reason I use high tech rope is simple, its lighter, a lot smaller in diameter, and so packs down a lot smaller, plus I hammock, its amazing how quickly you can ramp up the loading on your suspension just by changing the hang angle, having a 3mm rope with over 1000 lb breaking load, gives me piece of mind.

Cheers

Stephen

 

[Peter_t]

how many pies have you guys been eating!?

im sorry but all this talk of dyneema and spectra for hammocks is an extreme case off over the top!
dyneema and such materials are designed for the most demanding tasks such as replacing wire tow ropes or taking huge shock loads!

imo for a hammock you would only need a rope with a 2:1 safety factor, only twice your weight. this will take into account any loss of strength due to knots, general wear etc. but any more is unnecessary. so really all you need is a cheep rope or webbing with a suitable thickness to grip the tree without causing damage to thin barked trees.

or am i missing something? what is wrong with nylon or polyester?
feel free to get expensive technical ropes but trust me your wasting your time and money


pete