# Thread: Quick line question...

1. I just sent HB a long e-mail explaining this stuff as best I understand it.

The way I remember this, a knot generally reduces the strength of the line by 50%. And you do this for each knot. So if you start with 1600 strength and tie a knot to make a synch for the hammock end, then the strength is now 800. Then add another knot to tie the line to the straps and you are at about 400 strength... (please correct me if I am wrong).

Then take your hammock angle. 30% being optimal, that would mean that each line would support the same amount of weight, so a 200 pound man would put 200 pounds of force on each line. Again, correct me if I am wrong.

And this is just static weight. If there were some wind blowing and swaying, the weight is then calculated at weight*velocity^2, so a 200 pound guy could easily cause 400 pounds of force. And if the line gets wet in the rain it also loses some strength, which explains why both times I broke support lines on my old homemade hammock the lines were wet and the wind was blowing. That was prior to using dynaglide and/or amsteel.

2. I believe you are correct on all your assertions other than the knot derate being cumulative.

3. please post your findings Sgt Rock as everything your posting is a learning experience for all of us on yur findings about line strength. I never paid attention but always using amsteel just for the over strength effects so that I wouldn't worry about breakage. I use 1/8th myself and sacrifice a couple of ozs.

4. FWIW - I think you should look beyond climbing ropes. Sampson Utility braide exceeds your spec and stretches less.

http://www.samsonrope.com/index.cfm?...ope=111&inst=1

5. Originally Posted by opie
I believe you are correct on all your assertions other than the knot derate being cumulative.
You are right. I went and looked up my source for the factoid that multiple knots mean increased reduction in strength. It looks like he meant it as a jest.

6. I got an answer back from HB. Looks like their 6 mm rope is rated at a breaking strength of 1221 lbs. So if you went with the generally accepted 5:1 ratio, that means you are looking at 244 pound limit.

7. Im surprised they are calling it "climbing" rope with a number that low.

All in all I think its safe for hanging, however, at that number.

8. I agree with everything you just said.

To be fair to Hammock Bliss I'm editing some new material into the review. It should be uploaded tonight.

If it were me I would make the tarp out of sil-nylon and nanoseum net, and make the bottom out of tyvek instead of "parachute material". Then I would do a continuous ridge-line out of something lighter and attach it with prusiks, it doesn't need to be 1221 lb rope for that. After all that, I would replace the climbing rope on the hammock with Dynaglide WS. I'd probably make the tarp about a foot wider too.

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