This post should be a sticky! Itd be great if it listed typical use (I.e. which are best for whoopie slings and in what diameters, etc)Originally Posted by BER
This post should be a sticky! Itd be great if it listed typical use (I.e. which are best for whoopie slings and in what diameters, etc)
I knew that if we whispered his name, Demostix would appear and give us a more technical answer. I thought I was obsessed with cord for a while, but he...
Any of the single braid dyneema cords can be used to make whoopies and a variety of other spliced creations. It is merely a matter of looking at the breaking strength of each product and picking the right one based on the expected use (load), and a factored safety rating (many here use 5x load as the safety factor for hammock suspensions, though you could argue to use a higher rating if you were hanging from heights or using these cords for some other critical safety application).
In general, most here use dynaglide, 7/64" amsteel, or 1/8" amsteel for hammock suspensions, dependent on their own weight and perceived comfort in the safety factor. The breaking strength increases in that same order, as does the cord weight and bulkiness. Unless you are really trying to shave grams from your pack weight, there is little benefit to using dynaglide over 7/64" amsteel.
Lash-it/Zing-it are usually reserved for non-weight bearing applications such as tarp lines, accessory cords, and sometimes ridgelines.
Last edited by BER; 08-22-2012 at 09:23.
I was gonna say man... You uttered the name!I knew that if we whispered his name, Demostix would appear and give us a more technical answer. I thought I was obsessed with cord for a while, but he...
Demostix, you're a treasure.
Some say I'm apathetic, but I don't care. - Randy
Not to provoke too much concern for fatigue wear: Most of this stuff is used in the fishing industry, where stress is constant and cordage is being passed over drums and around turnstiles....... for a few years before replacement.
On safety: Safety is safety. Personally, I'd spend a night or even a whole trip hanging in my hammock from my 400lb bs guy lines, if the choice were that or trying to sleep on the ground. (Of course, thin as they are, I'd take care to see the lines didn't cut anything. I also would not hang over rocks, and I would not cut the margin even further by tying knots, so I'd have to do some field splicing.)
But, I don't commend this (mild) recklessness to anyone else.
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For this thread, even though I've noted this elsewhere:
You can calculate actual and volume savings in not having "excessive" strength or wanting more of it, or more safety, and then decide on the value to you.
These Dyneema-constructed cords have almost the density of water, once they have been in use. They may start hollow and with spaces between the strands, but all of that goes away.
There are 2 tablespoons to an ounce...by weight as well as volume for water.......or this cordage. Saving an ounce =saving 2 tablespoons.
Look at the ounces of cord you might use, say 5.4oz of a full 100 feet of Amsteel Blue 2.5mm / 7/64 with a BS of 1600lb. (That's < $25 worth.)
Because bs is approximately proportional to volume of cord, what you are going to save by substituting can be immediately calculated. And you can compare it to, say, your 2700 cu in back pack capacity.
For example: Make 50 ft of that cordage thin Lash It instead of 7/64, and you'll save 1/2 X 3/4 (that's the saving for 400lb bs cord -- 1200- 3/4 of 1600) x 5.4 oz...........2oz = 4 tablespoons.
Or, going the other way: Compare the cost and suffering of losing 50 lb --dieting, giving up beer, gastric bypass surgery, all new clothes (except hats and shoes and socks) vs the burden of heavier 1/8" / 3mm Amsteel Blue whoopie slings. What's an extra 1/2 oz of barely chunkier but still lean & mean Amsteel Blue when you are already carrying an extra 800 ounces of hydrated fat?
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Yes, I have a table I've assembled of much of the thin hi-zoot cordage sold. If I knew the numbers were close to correct, I'd post it.
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For now, and for hangers of the Commonwealth and EU: Stein Safety's orange throw line seems to be the same stuff as Dynaglide. Exact same construction and specs.
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Finally, something about price. For Amsteel Blue from our friends at Redden Marine and from those who will price match: Price seems to be pretty much proportional to amount = weight of cordage. A problem I admit to having with Dynaglide is that its price is outside that price/quantity envelope, and then there's waste and burden of 180' lengths. (from many, not all vendors.)
Last edited by DemostiX; 08-22-2012 at 18:47. Reason: clarity
All of this info stuffed into my head just killed about 20 braincells. My head hurts and now I need a beer. You guys are Hammock geeks as I am a Systems geek. I am an inspiring Hammock geek. I'm working on it. I think the thing we run into is that this forum is very diverse. Many people in many walks of life who have so much knowledge about different things. My interview is over. It went great, then I get smacked in the face by numbers and related facts to cordage that makes me rethink my ENTIRE ridgeline strength (other than my hammock suspension which is on par).
Now my head really hurts. I'm going to go hang my hammock from my 7/64 amsteel and my ratchet straps with toggles. Time to relax.
DemostiX, How do you sleep at night?
Some say I'm apathetic, but I don't care. - Randy
Just a small correction so no one gets confused when they get 7/64" Amsteel Blue. 7/64" Amsteel Blue is 8 strand. 1/8" and up is 12 Strand.
OMG. By the time I made my other post DemostiX posted with more info. So now my 7/64 isnt on par??? Sigh. Considering I've spent the money and taken the time to make my whoopies, I'm not changing them anytime soon. Cost, cost, cost.All of this info stuffed into my head just killed about 20 braincells. My head hurts and now I need a beer. You guys are Hammock geeks as I am a Systems geek. I am an inspiring Hammock geek. I'm working on it. I think the thing we run into is that this forum is very diverse. Many people in many walks of life who have so much knowledge about different things. My interview is over. It went great, then I get smacked in the face by numbers and related facts to cordage that makes me rethink my ENTIRE ridgeline strength (other than my hammock suspension which is on par).
Now my head really hurts. I'm going to go hang my hammock from my 7/64 amsteel and my ratchet straps with toggles. Time to relax.
Here's the jist: I'm 5'1 and 170LBS. So according to the factoid numbers the 7/64 should be good for me as long as I dont tie knots in it. Correct? Well I now run into an issue. I've posted pics of how I extended my hammock to increase the flat area of it. I used a loop over lock with two eye splices. This isnt exactly a knot per-say, but I'm sure it decreases the stregth somehow. At this point I'll just pray and jump on my hammock really hard and see what happens. I'm going to do this in a safe environment of course. Time to head into the yard and play! I love it when someone gives me an excuse to stress equipment. Just like one of my sons said my backpack couldnt hold my weight if I hung myself by the pack. WRONG. My osprey atmos held just fine. Although I did have to use a ladder to get down.
Last edited by Oper8or; 08-22-2012 at 11:54. Reason: grr text wrong
Oops, yes, you are correct. Sorry.
Right. The 7/64" / 2.5mm Amsteel Blue cord is at a sweet spot, Split a 200lb load in half between two hammock ends and 100lb is near the recommended load factor for cordage as a fraction of breaking strength (16 to 1 average, 14 to 1 minimum wrt the cord strength.)
Further, usual load factors always anticipate termination losses from knots -- a rope not connected to anything is useless. Most everyone here follows best practice in splicing terminations for serious weight bearing-- that is in the hammock suspension-- so instead of 30-50% expected strength losses from the get-go, there may be no more than 10% loss from that source..
Last edited by DemostiX; 08-22-2012 at 18:50.
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