Strength of rigging parts

[animalcontrol]

I bet alot of HH users taking their hammocks right out of the bag are overtightening. I don't remember anything in the derections aboutusing an angle.

everyone I know...I try to explain "hang'em high" rationale but I sound foolish mostly

[warbonnetguy]

For instance, for a HH ULB at a 12 foot span, all it takes is 0.8 inch stretch on each suspension line to get the hammock to drop 5.5 inches and you end up with a 14.5 degree suspension angle that represents 2x the users weight on each suspension line. At a 20 foot span, it takes a 2.4 inch stretch on each suspension line to get an 18 inch drop with that 14.4 degree suspension sag angle.

dave, are you saying you measured a 14.5 deg angle with someone in the hammock or was this an equation?

[warbonnetguy]

I think to say that 20 deg is not possible is foolish if it is interpreted as an absolute statement and you really mean that is your best guess based on what you have noticed. Someone can always re-tighten things and do it in a 'manly' way. I don't think we know what the limit is. Folks can use a truckers hitch to gain mechanical advantage or other means to get who knows how much force on the suspension lines.

ok, i don't "think" it's possible.

and i did use a trucker's hitch (3:1) with low stretch amsteel blue for the susp. and rl, and only got as low as 25 deg.

[warbonnetguy]

It is reasonable to expect that certain attachment methods at the trees might limit the minimum suspension sag angle more than other attachment methods. When you have webbing with carabiners, multi-wrap technique, webbing passing through webbing loop and suspension rope attached to only one of the webbing loops, tree huggers where the suspension rope attaches to both webbing loops, a non-cinching loop with a slippery bow line knot, etc, you have a wide variety of attachment methods and they may not all perform the same way where this issue is concerned.

i agree, many methods allow for more stretch and getting a really low angle wouldn't be as possible for certain setups. that's why i tried the truckers, because i thought i could get it tighter than with traditional methods although i might be wrong, the trucker's is tied off with a knot which lets out slack as it tightens down, maybe cinch buckles would have been a better choice, but i think a longer span would make it alot harder to get a low angle simply due to the more inches of stretch you get from having more cordage in use.

i guess the only way to resolve this is to try again and see "how low can you go" i really thought somebody would go out in their yard and try to see what vacinity the lowest angle is with re-tightening, oh well. i'll definately try it at some point, but you need 2 people and the right trees so i don't know when i'll get a chance, but i just don't think really low angles are possible.

[warbonnetguy]

It is true that the angle will tell you the forces that are on the weighted suspension at that instant. It won't tell you the forces that might have been on it before that instant-- the forces that caused something to give, stretch, or reposition to relieve what might have been a higher force when you started with a near-zero suspension sag angle.

well, i see where you're coming from here. for a short span of time the angle is much less, but considering the extremely low weight/force it takes to "drop" the hammock to a much higher angle, i don't see how it would be more force than it is after the hammock is fully weighted. for instance when i pull the suspesnion horizontal, i can pull on the bottom of the hammock with my hand and get it to drop most of the way with very little force. you could probably go from zero to 15deg by throwing a good sized book in the hammock, yeah it's multiplied by a larger number at that angle, but the suspension only holds a tiny fraction of bodyweight at those low angles so it doesn't seem the overall force could be as high during the "drop phase" when your feet are still on the ground holding the majority of your bodyweight.

[Youngblood]

dave, are you saying you measured a 14.5 deg angle with someone in the hammock or was this an equation?

As I stated in the first part of the paragraph, I came up with those numbers by going through the geometry and force calculations:

"It isn't difficult to go through the geometry and force calculations to see how much stretch and drop you get for particular sag angles when you started from a near-zero sag angle (this assumes it is all stretch of the suspension line), I have done that before. For instance, for a HH ULB at a 12 foot span, all it takes is 0.8 inch stretch on each suspension line to get the hammock to drop 5.5 inches and you end up with a 14.5 degree suspension angle that represents 2x the users weight on each suspension line. At a 20 foot span, it takes a 2.4 inch stretch on each suspension line to get an 18 inch drop with that 14.4 degree suspension sag angle."

[warbonnetguy]

As I stated in the first part of the paragraph, I came up with those numbers by going through the geometry and force calculations:

sorry, should have read that closer.

[warbonnetguy]

anybody know who has the best deal on cinch buckles?

[warbonnetguy]

dave, i just ordered a yates screamer. basically a shock absorbing webbing device where some of the stitches rip at a certain point to absorb shock. the one i got activates at 2kn with an accuracy of +/-5%, so it should activate roughly somewhere between 420# and 470#.

http://www.yatesgear.com/climbing/screamer/index.htm#1

[Youngblood]

dave, i just ordered a yates screamer. basically a shock absorbing webbing device where some of the stitches rip at a certain point to absorb shock. the one i got activates at 2kn with an accuracy of +/-5%, so it should activate roughly somewhere between 420# and 470#.

http://www.yatesgear.com/climbing/screamer/index.htm#1

Brandon, I'm not familiar with them but looked over the link to get an idea. It will be interesting to see how they work to measure the peak load on a hammock suspension. I didn't notice what they were made of but would guess it is nylon. In the hammock suspension line application you need something that doesn't stretch because that stretch will reduce the force you are trying to measure, I don't think that is the case for their intended application.