Tech Line Hammock Suspension

**Chrisman2013** · 07-07-2012, 15:44

So I had done some calculations recently and it seemed to me that the 1.9mm Tech Line from DIY Gear Supply might very well be strong enough for me to make a hammock suspension out of. I tested that today by putting a two foot long extension onto my current UCR. It worked fine. It didn't break or fray even after I bounced in my hammock very hard. Now my plan is to make a suspension system out of the line. Are there any problems anyone foresees? BTW I only weigh 145#
Thanks, Chris

**FireInMyBones** · 07-07-2012, 15:59

I was just thinking about trying something like this (I weigh 150 lbs) earlier today.

**Chrisman2013** · 07-07-2012, 16:29

Well earlier today the two foot section I hung from held up great even when I bounced around in the hammock an abnormal amount. So I'm really pretty comfortable using this for my suspension but I just wanted to see if anyone had any input. I'm unsure of long-term durability though so after I make a suspension out of this it will be interesting to see how it holds up. (I also tried testing a section of 1.2mm Tech Line. I sat down in the hammock without it breaking but as I swung my legs up into the hammock the line snapped. I wasn't broken at the splices but approximately in the center of the section.) My plan is to make a new suspension system using 1.9mm Tech Line for UCRs and 1.2mm Tech Line for a ridgeline, or I might skip the ridgeline altogether for addition weight and space savings.

**BrianWillan** · 07-07-2012, 16:46

Do what you wish in regards to your hammock suspension, but 1.9 mm tech line has a mere 480 pound break strength. That would be fine if you always get your suspension angle very close to the magic 30 degree mark. Which reduces the force on the line to your body weight. With you being a light weight at less than 150 pounds that gives a 3 times safety factor.

But be sure to splice the line for minimum losses in rating and avoid knots at all cost on your hammock suspension. Also keep in mind the golden rule of hammocks and hang it no higher than you are willing to fall.

Cheers

Brian

**DemostiX** · 07-07-2012, 16:59

You use line which is not only strong enough to support you -- or someone else who may use the hammock --, but also to provide a safety margin.

If you are a slow and lazy 100lb fish, you might be disappointed to be reeled in by a skillful angler after swallowing the bait on 50lb line. Not impossible. Similar happens all the time.

But, as we are not fish, most of us follow the advice to have a safety margin over the breaking strength with a factor of 10 to 15. That covers a multitude of faults, anything from dynamic loading -- your bouncing, or falling back onto hammock -- to knot lossses to frayed strands you haven't yet noticed. And then there's fatigue. After initially growing a bit stronger, well-stressed line fatigues with time, and then fails catastrophically, without notice. That is true for steel as well as fiber.

Stress? Repeated high level loads, or long term sustained load which is a high fraction of the breaking strength. In the case of Amsteel and similar, that load is something like 30% of breaking strength. So, it creeps, getting slightly longer over time. And then it breaks, at just that fraction of breaking strength.

The cost to you and to other hammockers of seeing how little line you can use without failure is potentially high. Calculate the grams or $ savings, and it is very small. Just over $0.20 /ft gets you lightweight Amsteel Blue with a minimum breaking strength of 1400lb and an average of 1600 lb. Nothing wimpy about a safety margin of 20 instead of 15 times.

BTW: Ridgelines are typically very lightly loaded. But, under the conditions of overload and failure of one that is depended on, the resultant load on the hammock and its suspension from the trees will surely --not possible, but SURELY -- break one of those Tech lines. The words in the previous sentence were carefully chosen. Set up the mattress for you to fall on and I will take serious, serious money at odds favorable to you, of your needing the mattress for your safety. After the ridge-line fails, so will the Tech line.

**Kzoo** · 07-07-2012, 17:24

Apart from the very good points Demostix mentioned, another concern is how you're connecting the tech line to your hammock. I have amsteel lark's headed over the whipped ends of my hammock. I would be concerned about using a smaller diameter cord for fear of it wearing through and cutting my hammock.

I weigh less than you, I'm cheap, and I pay attention to grams but I wouldn't use tech line as my suspension. Still, it's your butt in the air.

**hangnout** · 07-07-2012, 17:31

Originally Posted by Chrisman2013

So I had done some calculations recently and it seemed to me that the 1.9mm Tech Line from DIY Gear Supply might very well be strong enough for me to make a hammock suspension out of. I tested that today by putting a two foot long extension onto my current UCR. It worked fine. It didn't break or fray even after I bounced in my hammock very hard. Now my plan is to make a suspension system out of the line. Are there any problems anyone foresees? BTW I only weigh 145#
Thanks, Chris

Pushing the limits requires planning for failure which in this case means planning for a soft landing. I always hang over rocks etc so I will stop at the dynaglide Pushing the limits is what we do, just do it safely.

I bet if you are pushing your suspension to those limits you have already pushed your hammock to the lightest fabric you can. That is were the problem will happen. The 1.9 tech line will saw thru a lightweight fabric after a few hangs. The dynaglide is slicker and keeps a round shape. The tech line is rough and flat. I would make sure the line is wrapped several times around the hammock or use a triple sheet bend attachment to hammock.

Just my opinion and my wife says it ain't worth much

BTW Kzoo gave the same advice while I was typing

**Chrisman2013** · 07-07-2012, 19:48

Great points! I'm glad to get some discussion. I think that I will continue on with my idea. I'm very careful with my gear which should reduce the risks. In addition, because of school and running I don't have as much time to backpack as I would like. The idea isn't to use this on a thru-hike but rather shorter weekend to week-long hikes. The shorter hikes should reduce the chance of failure due to fatigue. On the subject of fabric wear, I use an end channel hammock. My idea is either to reinforce the ends of the channel with grosgrain webbing or to use Dynaglide through the channels and then connect that to the Tech Line. My idea in using the Tech Line is just to lower weight and space. Always pushing the limits.... Next up, a Cuben hammock...

**MAD777** · 07-07-2012, 20:36

I'm no stranger to pushing limits in the name of lightening up. I'm currently hanging on Dynaglide (I weigh 200#).

Someone at last year's Florida hang had their 1.75mm Zing-it ridgeline snap right in the middle. They obviously had the hammock strung tight, but that doesn't give me much confidence in something less than Dynaglide for a suspension. As Demostix alluded to, there is always Murphy's Law to be concerned with.

I would recommend that you carry a back-up suspension with you on your first few outings. That's what I do when I'm trying something new.

We're looking forward to your long-term report!
In the mean time, inspect the ground under your hammock for any painful debris

**Chrisman2013** · 07-07-2012, 20:53

Once I get it all rigged up I'll be sure to post updates. Maybe I'll get someone else started on it. FireInMyBones sounds like he might try it too. I'll also be sure to have a video camera handy the first couple times I hang in it.