Are our suspensions systems safe

[DemostiX]

While your general thoughts here are very good and the condition of used amsteel most certainly effects ultimate strength, I had a slightly different take away from the discussions in your older thread on bend radius. In particular, the info direct from a Samson engineer contained in posts 27 and 28..."It has been observed in testing of AmSteel Blue with spliced eyes on small diameter pins, providing a D/d ratio of 1, that the breaking strength is not significantly affected."

I do agree that greater bend radii provide a greater margin of error, but even the relatively thin Dutch Whoopie Hook has a slightly better than 1:1 ratio and should maintain the single line strength rating of 7/64" amsteel.

As always, we should continue to remind others that lighter equipment and pushing the edge of ratings requires frequent inspection of your equipment.

And along those lines, thank you for bringing this neglected topic up.

No, this is a misunderstanding and impossible in the context of the entire reply I just read.

"However, things get a bit more complicated if you are talking about the strength of endless loop, or grommet, slings. All tension members experience a decrease in strength when loaded over a bend due to the uneven loading of the top and bottom sections in the bend. As the diameter of the bend decreases, the load on the outer portion of a rope increases.

Testing has shown this reduction in strength no longer has a significant effect on AmSteel Blue at D/d ratios greater than 20, where “D” is the diameter of the bend and “d” the diameter of the rope. This means that at very large D/d ratios, a grommet sling has a breaking strength twice that as a single part of line as there are two legs of the sling contributing strength. At lower D/d ratios however, the contribution of both legs is limited by the strength loss due to the bend. This does not impact eye-each-end slings on pins with D/d ratios as low as 2 however since there are two legs supporting the eye and a single leg holding the entire load in the center of the rope.

In short, the limit we recommend for attaining full strength of a single leg sling are pin diameters at least twice the diameter of the rope"


The engineer is comparing strength of slings with double lines. Catch that "since there are two legs supporting the eye".


The same confusion used to be repeatedly expressed here in assessing soft shackles. One would hope for double stength due to doubled cordage, but testing has shown the strength should be more safely assumed to be that of single lengths of the cordage.

What also seems missing is an appreciation of how the failure occurs. Not always immediately, but over time, as the cord fatigues due to excessive loading on the portion on the outside of pin.

Nothing in the Samson reply is contrary to everything from the Cordage Institute and every other reliable engineering source on depreciating the strength of rope.

[gmcttr]

...In particular, the info direct from a Samson engineer contained in posts 27 and 28..."It has been observed in testing of AmSteel Blue with spliced eyes on small diameter pins, providing a D/d ratio of 1, that the breaking strength is not significantly affected."...

No, this is a misunderstanding and impossible in the context of the entire reply I just read....

The text highlighted in red is a direct quote by a Samson Rope Application Engineer taken from an email to me in response to this question..."1 - Stepping outside of recommended usage, what percentage of published minimum breaking strength is attained when the D/d ratio is only 1 for the two smallest diameters of Amsteel Blue?" This question was about the breaking strength of an "eye both ends single leg sample", what we call a dog bone. Not a grommet sling. This was about actual data and not the published recommend pin diameter.

While I agree that each less than optimal thing we do with amsteel derates the rope to some unknown extent, several years of anecdotal evidence on hammocker's usage of amsteel has not shown the back of pin failure mode to be problematic.

...And that's all I have to say about that.

[lostagain]

straps and buckles for me, though I do have one hammock that has whoopies. haven't hung with it yet, but I will, though....I'm probably gonna die!

[Floridahanger]

straps and buckles for me, though I do have one hammock that has whoopies. haven't hung with it yet, but I will, though....I'm probably gonna die!

Only if the Whoopies are made of zing-it. Yikes!

[Pixabilly]

I am heavy guy, 120kg (260lbs) and i got myself a TTTM hammock. But i don't trust the rope suspension
I will get myself webbing and buckles, thinking those dutchware strapbuckles. Aluminium, are they strong ones? Amsteel is not available in finland, boo.

[gmcttr]

I believe Dutch uses webbing with a 1500 lb breaking strength.

[dirtwheels]

This company bought New England Ropes and has multiple products available, they are the makers of dynaglide. They also sell other products:

Their STS product should work for hammock suspension:

http://www.teufelberger.com/en/produ...han-steel.html

Their endura 12 is also available, I've been hanging nightly for a couple of months on 2 mm dogbones with no hint of degradation. It is their marine equivalent to dynaglide.

http://www.teufelberger.com/en/produ...ndura-12.html#

I corresponded with New England ropes prior to the buyout and found them quite helpful. Just thought I'd highlight a vendor on your side of the pond.

http://www.teufelberger.com/en/home-2012.html

I just purchased a pair of Dutch buckles and they appear to be a nice piece of kit, hope to try them out this weekend. Dutch is also developing titanium cinch buckles.

I am heavy guy, 120kg (260lbs) and i got myself a TTTM hammock. But i don't trust the rope suspension
I will get myself webbing and buckles, thinking those dutchware strapbuckles. Aluminium, are they strong ones? Amsteel is not available in finland, boo.

[FLRider]

I've, personally, seen at least one person able to hang from line rated at 400 lbs.

I don't particularly subscribe to that for my personal suspension, as the weight savings are less than the perceived danger for me. That means I'd get less rest over it than the weight savings would provide.

Personally, I use 7/64" Amsteel and 1,500-lb rated straps, with six bartacks to hold the eye in the straps. This gives me (assuming a 30* hang--which is not always possible, but definitely something that I shoot for) greater than a 5-to-1 safety factor versus the weight rating of the components.

I'm fairly confident in that rating, but I'm also careful getting into and out of the hammock and I ensure that I don't have any sharps on me while in the hammock. I also inspect my suspension after every trip.

I may be whistling in the dark here, but that's worked for me so far. If and when I wind up getting dumped by my suspension, you folks will be the second group that knows (family being first).

[Floridahanger]

I've, personally, seen at least one person able to hang from line rated at 400 lbs.

I don't particularly subscribe to that for my personal suspension, as the weight savings are less than the perceived danger for me...
...Personally, I use 7/64" Amsteel...

I use the 7/64 Amsteel for my cordage, but my straps are Walmart cargo straps rated ~400lbs. It's definitely not for the weight savings as much as the $ savings. I'm sure I could get lighter and less bulky straps from any of our cottage vendors, but, I don't have the funds for them. The WW straps are ~$5 for 2, 12' straps I make into 4, 6' straps. I've tested and was happy with them.

I still use my original straps for 3 years now. Also, I always check them everytime I remove them from the trees and everytime I remove the toggles.

[MAD777]

Check the labeling on those Walmart straps, Floridahanger. The 400# may be the "working" strength, not the "break" strength. If so, they would be rated about 1200# "break" strength, which is what everyone is referring to here on the forum.
(Maybe you're not such a dare-devil after all )