Hammock question

Posted by: PaHiker

Hammock question - 02/05/16 10:51 PM

I made a basic hammock a few years ago, I am looking at modifications to cut down on weight and make the whole thing easier to use. One of my mods is to switch out some of the straps with 550. My question is, can 550 be used for the main straps between the hammock itself and the straps that wrap the tree?

Here is my thought: strap around the tree ending in aluminum carabiners. 550 coming off the end of the hammock and connecting to the carabiner.



Looking at the photo above, I'm not sure what type of cord they used, but my plan was the 550. FYI, I am about 175 lbs. My concern was he added stress that would be put on the cord beyond my 175 lbs.

Note: I am not replacing the tree straps because they do offer some protection to the tree itself.
Posted by: 4evrplan

Re: Hammock question - 02/05/16 11:25 PM

I wouldn't use 550. Due to the geometry of a hammock suspension and loss of strength at knots, it really isn't strong enough. And, it has a LOT of stretch to it. And, it soaks up water. What you want, and what is most likely in the picture is some type of braided dyneema cord. Amsteel Blue 7/64" is the most popular. Only thing is, it doesn't take knots well, so you need to splice it and/or use special hardware. I highly recommend watching Shug Emory's hammock videos on YouTube or read through the stickies on the suspension subforum at hammockforums.net.
Posted by: Dryer

Re: Hammock question - 02/06/16 10:19 PM

I've had 550 break, with me in my hammock, and dump me. Lucky I was only about a foot high.
Have a look a Amsteel Blue. Amazing strength for very thin suspension line.
http://www.samsonrope.com/Pages/Product.aspx?ProductID=872
Posted by: finallyME

Re: Hammock question - 02/08/16 10:34 AM

Never use 550 in hammock suspension. It stretches too much and can't hold the weight. You are actually putting more stress on it than 550 lbs. Look at the amsteel stuff, or go to a climbing store and buy either 4 mm static line or 5 mm static line.
5mm line

By the way, the stuff in your picture looks like amsteel.
Posted by: PaHiker

Re: Hammock question - 02/08/16 11:21 AM

How does this hold a knot?
Posted by: 4evrplan

Re: Hammock question - 02/08/16 11:59 AM

Originally Posted By PaHiker
How does this hold a knot?

If you mean Amsteel, it doesn't, not very well. Dyneema in general doesn't. That's why people generally splice it instead, meaning it's hollow, and you feed it through itself. When you put weight on it, it tightens up like a finger trap and the friction holds it in place. Again, you really need to read the suspension stickies on hammockforums.net. Start here.

ETA: Or if you're averse to the learning curve or the work building your own suspension, you can get pre-made suspension here.
Posted by: PaHiker

Re: Hammock question - 02/08/16 12:01 PM

Yeah, found that out.
I was asking about the static line.
Posted by: 4evrplan

Re: Hammock question - 02/08/16 12:02 PM

Oh, my mistake.
Posted by: finallyME

Re: Hammock question - 02/08/16 05:30 PM

I have found that the static lines hold knots very well. They are made for climbing and tying knots in them.
Posted by: PaHiker

Re: Hammock question - 02/08/16 05:34 PM

Okay, thanks.
BTW, love the Husky, I have one as well. Few other dogs are able to keep up with my hikes, especially in the winter months.
Posted by: PaHiker

Re: Hammock question - 02/09/16 08:04 AM

I actually had a good laugh at that. During my initial testing of my hammock suspension I've had a number of setups fail on me, and at heights more than a foot. Fortunately, I did my testing on the trails of a local county park under a spread of hemlock trees, the needles covering the ground made for a soft landing.
Posted by: Dryer

Re: Hammock question - 02/09/16 09:04 AM

I've only broken a suspension line once...and it gave me some warning, but there is absolutely nothing you can do! Nothing to hold on too, no way to brace for impact. So, para-cord or 550 has been banned from my life. grin My Hennessey's all have Spectra and have never shown any sign of wear or stress. My home-made hammocks are plain old nylon braid and work great. Not the lightest in the world but it's functional. In sailing, I've found Amsteel to hold knots just fine if you use the right knots. I'll be replacing the nylon braid with it someday.
Posted by: PaHiker

Re: Hammock question - 02/09/16 09:19 AM

I took 4everplan's suggestion and watched the video and read some of the suspension thread. I like the treehugger from the video, and the single line suspension from the thread. Will look into both of them, though the Amsteel Blue at $36 is a bit out of budget right now, will probably go for a less expensive, albeit heavier, solution.
Posted by: PaHiker

Re: Hammock question - 02/14/16 08:19 AM

Hey, if someone could answer, what is the minimum breakpoint I should consider for the ropes? Here are the specs for one I am considering:

The SPECS for 2mm - MBS: 225 lbs / 1.0 kN
The SPECS for 3mm - MBS: 585 lbs / 2.6 kN
The SPECS for 4mm - MBS: 1034 lbs / 4.6 kN
The SPECS for 5mm - MBS: 1124 lbs / 5.0 kN
The SPECS for 6mm - MBS: 1978 lbs / 8.8 kN
The SPECS for 7mm - MBS: 2788 lbs / 12.4 kN
Posted by: Dryer

Re: Hammock question - 02/14/16 09:01 AM

Here, have fun with this:
http://theultimatehang.com/hammock-hang-calculator/

Play around with the angles and see what it does to tension loads.
Posted by: PaHiker

Re: Hammock question - 02/14/16 11:19 AM

I have been, own the app, but I figure there must be something more to it. I weigh in at 175, so my sheer force, weight, and tension are all below 200lb. Everyone recommends against Paracord 550, which is rated at 550 lbs, so there must be something more to it that what the app shows.
Posted by: Dryer

Re: Hammock question - 02/14/16 05:53 PM

I think it's specifically paracord not being consistent. It's anybody's guess who makes it and it's made differently that any other line. When mine failed and dropped me, I could hear the interior strands braking before complete failure.
Go with something spec'd by the manufacturer, or certified, like climbing lines.
Posted by: PaHiker

Re: Hammock question - 02/14/16 07:14 PM

Ok, so I should be good with the 4mm rated at 1,034 lbs. Good, that's within my budget. These are the two months all of our local school taxes, home and auto insurance, and income taxes are due. Takes a couple more months to get back to sanity.
Posted by: finallyME

Re: Hammock question - 02/17/16 09:59 AM

I use 4mm.
Posted by: PaHiker

Re: Hammock question - 02/17/16 10:21 AM

Thanks. I picked up 4mm from REI yesterday. Now I just need to determine my ridge length. Is there an easy way to calculate ideal based on a person's height?
Posted by: 4evrplan

Re: Hammock question - 02/17/16 12:47 PM

Most people recommend at least 11' for the hammock body itself, for comfort, regardless of occupant height. And, the rule of thumb for RL length is 83% of hammock length, hence 9' 1 9/16". If you want to dial it in to your preference, you can make an adjustable RL.
Posted by: 4evrplan

Re: Hammock question - 02/17/16 12:49 PM

I forgot you already made your hammock. If you want to make a fixed length RL, just take the length of your hammock and multiply by 0.83.
Posted by: PaHiker

Re: Hammock question - 02/17/16 02:39 PM

Thanks. I made a Risk hammock, will have to check it's length. I'm guessing something happened to him, his website is shut down.
Posted by: wgiles

Re: Hammock question - 02/29/16 08:44 PM

Safe working load on ropes is normally 25% of the breaking strength or less, depending on the application. Shock loading can often cause dramatic increases in the load. The load in a hammock suspension line at 30 degrees from the horizontal is roughly equal to the weight of the person in the hammock. The load would be one half the weight of the person if the lines were vertical. The closer the suspension lines are to horizontal, the higher the tension. If the suspension lines were horizontal, the tension would be infinite. A ridge line in the suspension will actually increase the tension in the support lines because they will normally be closer to horizontal than 30 degrees. Dyneema doesn't stretch very much, so shock loads are magnified and connections may fail. Moral: don't bounce around in your hammock. I use 1/8" or 5/32" Dyneema suspension lines and 1/8" Dyneema for my ridgeline. My suspension and ridgelines are also Whoopie slings. A whoopie sling ridgeline is really not a good idea, because it will creep under load cyling (when you get in and out). It's best to determine the length of the ridgeline and make one that is fixed length. I learned how to make locked brummel eyes, which aren't that hard to do, and use them in almost all of my tieout lines. I use knitting needles for my fids. Samson rope explains fids and splicing very well. Grog knots shows how to make locked brummel eyes.
Posted by: PaHiker

Re: Hammock question - 02/29/16 08:53 PM

My currently plans are to try the SLS system. My current setup uses strapping on both the tree wrap and hammock line.
Posted by: Dryer

Re: Hammock question - 03/01/16 08:19 AM

For my homemade hammocks, I start with 12' of material. After the hems on the ends, they end up around 11'6".
Posted by: PaHiker

Re: Hammock question - 03/01/16 08:51 AM

I worked off of Ed Speer's design, starts at 8', after hemming it's 7'9"