destructive testing

[Albert Skye]

It seems useful to do some destructive testing. As I understand it, Dyneema/Spectra (Amsteel) cordage is proportionally weakened by knots (loaded bends) much more than is nylon, for instance.

Some forum members appear to have lots of cordage and the inclination to sacrifice it for experiments, so I offer the suggestion to perform some tests (which I'm not prepared to do myself).

Obviously, very strong anchors are necessary. Pulleys can be used to multiply forces and water can be used to apply a measured load. I suggest testing the Garda hitch and the marlinspike hitch (especially with small-diameter pins), because those are so popular.

It should also prove interesting to test D:d strength, if nothing else, and discover how much the plot differs from that for wire rope.

[Running Feather]

There is a lot to digest here. Very interesting.

[Knotty]

If I had the gear I'd give it a try, just to satisfy my curiosity. Creating the load isn't the hard part. But how do you measure the load?

[angrysparrow]

But how do you measure the load?

I think that's why he suggested using water. The weight of it is known for the given quantity you add.

[oldgringo]

Assuming the line will fail somewhere north of 1000#, that's a lot of water.

Maybe some sort of rig that employs a known mechanical advantage would work.

[MacEntyre]

Assuming the line will fail somewhere north of 1000#, that's a lot of water.

Only 125 gallons.

Two 155 gal drums would probably do the trick. Each one, when full, would weigh about 1250 lbs.

- MacEntyre

[Dutch]

What I do is this;
I have a pallet scale that goes 2000+ and I also have molds that are around 2000 pounds at work. So I put the mold on the scale and lift using the towmotor. If I can lift it so there is 1000 left on the scale I guess it is around 1000. I watch the scale and see when it breaks. It isn't perfect science but it is a good representation. Don't tell my employer I am lifting his $80,000 molds up by webbing and rope.

So all you have to do is find someone with a similar set up and convince them to do it for you.

[oldgringo]

Only 125 gallons.

Two 155 gal drums would probably do the trick. Each one, when full, would weigh about 1250 lbs.

- MacEntyre

Don't guess I've ever seen 155 gal drums.

[MacEntyre]

Don't guess I've ever seen 155 gal drums.

That's a test, to see if anyone reads posts with numbers in them.

[JerryW]

Two 155 gal drums would probably do the trick. Each one, when full, would weigh about 1250 lbs.
- MacEntyre

Don't guess I've ever seen 155 gal drums.

That's a test, to see if anyone reads posts with numbers in them.

I was looking at your numbers, too...it would only be 1240 lbs.

What I do is this;
I have a pallet scale that goes 2000+ and I also have molds that are around 2000 pounds at work. So I put the mold on the scale and lift using the towmotor. If I can lift it so there is 1000 left on the scale I guess it is around 1000. I watch the scale and see when it breaks. It isn't perfect science but it is a good representation. Don't tell my employer I am lifting his $80,000 molds up by webbing and rope.

So all you have to do is find someone with a similar set up and convince them to do it for you.

Dutch, since you already have this neat set-up...