Load ratings of climbing equipment?

[SINGLE-JACK]

Since mass and weight are the same here on Mother Earth, isn't it the same in our applications?

:agree2: makes no practical difference at all for the work we do.

 

[mikewhite85]

I went down about 10 feet til my srt line found a crotch it liked better. I was tied to the rope with a Petzl hand ascender, no problem.

Ouch! That must have been a scare.

 

[treemandan]

Ouch! That must have been a scare.

No, had a good feeling my top crotch would break but made sure the rope would fall into another. Felt kinda good actually but that was cause I was prepared. if I suddenly unwittingly started to fall I would scream like a ...

 

[SINGLE-JACK]

No, had a good feeling my top crotch would break but made sure the rope would fall into another. Felt kinda good actually but that was cause I was prepared. if I suddenly unwittingly started to fall I would scream like a ...

:agree2: I did lol ... would rep that if I could.

 

[davej]

So that 27Kn carabiner should be rated to hold a force of over 6,000 lbs.

So Moray, will the typical hitch slide down and save your spine?

 

[outofmytree]

Since mass and weight are the same here on Mother Earth, isn't it the same in our applications?

I'm not a physicist JPS I just read Wiki! However if I recall from high school, way back in the stone age, weight and mass are not the same. Weight is relative, mass is fixed. You weigh less at 30, 000 feet in an aeroplane than you do diving for lobster. And of course we all wear our harnesses whilst flying and scuba diving right?

 

[John Paul Sanborn]

And of course we all wear our harnesses whilst flying and scuba diving right?

So I guess we actually agree, since we are at a relatively equal gravimentric, our mass does equal our weight in the given discussion

 

[John Paul Sanborn]

"The whole purpose of the metric system is to keep things simple ..."

Well, it is intended to be simple WITHIN the metric system = Meter-Kilogram-Second (MKS) system:

The idea was to make a universal system that would be easy to use, since we calculate in base ten it seamed like the thing to do. But then give it to carpenters, bricklayers, and bakers who think in base four, i.e. half and quarter measures, and it throws things off.

Brion Toss, a great proponent of keeping it english, has a story of working with some Euro woodworkers who had re-invented the fractional system for getting past the .25 measure. they were dumbfounded when he replies "oh, just like English standard!".

It might be burried on his site, I could not find it

 

[pdqdl]

...

The "small deviation" (101.64525412649) is due to the difference in the force of gravity on the International Prototype Kilogram and the force to accelerate the International Prototype Kilogram to 1 Meter per Second per Second. The inverse is referred to as the Gravitational Constant, "9.80665 m/s2".

...

I thought that when I first looked at the numbers, too. But it isn't the inverse of the gravitational constant. Just divide 1 (or one thousand) by 9.80665, and you will see a different number.

I already checked that! Close, but not quite the inverse. Hence, we don't quite know what we are missing. Perhaps nothing more than internet misinformation, since I only got my numbers from Wikipedia.

 

[SINGLE-JACK]

Notice that the conversion factor for Kilonewtons is NOT an even multiple of 10; rather, it is 101.64525412649. The whole purpose of the metric system is to keep things simple and easy to convert.

This small deviation is not enough to make much difference to most folks, but it points out to me that there is some facet of the kilonewtons (force) to Kilograms (mass) conversion that I do not know or understand. I suspect that it is related to the acceleration due to gravity, but I am not sure.
(defined to be precisely 9.80665 m/s2 )

...
The "small deviation" (101.64525412649) is due to the difference in the force of gravity on the International Prototype Kilogram and the force to accelerate the International Prototype Kilogram to 1 Meter per Second per Second. The inverse is referred to as the Gravitational Constant, "9.80665 m/s2".
...

I thought that when I first looked at the numbers, too. But it isn't the inverse of the gravitational constant. Just divide 1 (or one thousand) by 9.80665, and you will see a different number.

I already checked that! Close, but not quite the inverse. Hence, we don't quite know what we are missing. Perhaps nothing more than internet misinformation, since I only got my numbers from Wikipedia.

You are absolutely right! It is NOT the inverse (at any order of magnitude). So, I did some additional research and found:

1 kilogram-force (kgf or kilopond) = 9.80665 m/s2 = 9.80665 Newtons
- this value is defined by international agreement.
... inversely
1 Newton = 0.101971621 kgf = 101.971621 grams-force
1 kiloNewton = 101.971621 kgf

An internet search for the number "101.64525412649" had only two hits: your post and my post, referencing it. Though it is close, I was remiss in assuming it to be the inverse of 9.80665 m/s2. So, it appears, the value "101.64525412649" is suspect, as you suggest it is "Perhaps nothing more than internet misinformation".

 

[lync]

while climbing srt (line over a crotch,tied off to base of tree) an unseen smaller limb above my tip crotch broke, i dropped about 6 ft. i'm 220 lbs, cmi ascender did no damage to the rope. It was a tall spruce i knew I was in something solid, I bounce tested the ascent rope from the ground before I started.

 

[pdqdl]

Quite frankly, I could not find my original internet source for that screwed up number. At this point, I will assume that:

1. 101.64525412649 is wrong, and that I passed on bad information to you guys.

2. 101.971621298 is correct, that it is 1000 x the inverse of the gravitational constant, thereby making everything fit together the way I wanted it to in the beginning.

My confidence in the metric system is restored, and my distrust of the internet is renewed.

SingleJack: Thanks for doing the research that I was too lazy to complete myself!

 

[oscar4883]

"The metric system is a tool of the devil. My car gets 40 rods to the hogs head, and thats the way I like it"
-Grandpa Simpson when questioning the installation of a mono-rail in Springfield.

 

[SINGLE-JACK]

...
My confidence in the metric system is restored, and my distrust of the internet is renewed.

SingleJack: Thanks for doing the research ...

Ain't-no-thang!

I had to do the research ... they hadn't even invented the "kilo Newton" when I went to school ... LOL!!!


- Jack

 

[moray]

So Moray, will the typical hitch slide down and save your spine?

Well, yeah, I do want to do some tests on hitches and dynamic loads, but there are two feet of cold snow sitting on top of my rig right now. Come spring (roughly August in these parts) I'll be back at it.

Do you guys want me to start posting results in kN?

 

[SINGLE-JACK]

Well, yeah, I do want to do some tests on hitches and dynamic loads, but there are two feet of cold snow sitting on top of my rig right now. Come spring (roughly August in these parts) I'll be back at it.

Do you guys want me to start posting results in kN?

LMAO!!! Yeah, what...ev...er, we got the math fingered out now ... pounds are OK ... kN's are kool ...
maybe: Slugs per Furlong per Fortnight ... :monkey:

Happy New Year moray,
Jack

 

[moray]

... maybe: Slugs per Furlong per Fortnight ...

That's very good, SJ! Where did they ever come up with slugs? Same place they came up with shillings and pounds and guineas. Those Brits.

I'm off for 3 weeks to a warm place where they don't speak English and no one has ever seen snow. They do have Internet, so I'll have to see if I can get connected...

 

[bendtrees]

The thing that freaks me out is that our saddles our rated for "work positioning" not "fall protection". Always give me a second thought prior to climbing above my TIP. Especially looking down at the silly little clevis' on my Butterfly which probably pull at angles which will double any load placed upon them, (or so I imagine). I'm a bit unclear about what the standards and differences are between the above terms. What are our saddles rated to?

 

[outofmytree]

The thing that freaks me out is that our saddles our rated for "work positioning" not "fall protection". Always give me a second thought prior to climbing above my TIP. Especially looking down at the silly little clevis' on my Butterfly which probably pull at angles which will double any load placed upon them, (or so I imagine). I'm a bit unclear about what the standards and differences are between the above terms. What are our saddles rated to?

Each fixing point on my Sequoia is rated to 15kn. All you have to do now is go back up this thread and figure out what that means.

I think it is safe to say that any fall which creates enough force via gravity to "break" a climbing saddle will be great enough to "break" the climber upon impact. Alternatively if your saddle holds, you will resemble a pretzel. Comforting thought isn't it?

 

[SINGLE-JACK]

Each fixing point on my Sequoia is rated to 15kn. All you have to do now is go back up this thread and figure out what that means.

I think it is safe to say that any fall which creates enough force via gravity to "break" a climbing saddle will be great enough to "break" the climber upon impact. Alternatively if your saddle holds, you will resemble a pretzel. Comforting thought isn't it?

:agree2:

Good point! ... This is an important point to stress, here. You don't have to fall to the ground to die or get seriously injured. If you haven't been tending your slack and fall ten feet, and are positioned wrong, there's a risk you could break your back when your slack snaps tight.

Tree workers use static line because it increases the efficiency when climbing a rope. But, it also increases the risk of injury from even a minor fall because there is very little forgiving shock absorption in static line. Dynamic line, used by rock climbers, is much, much more forgiving ('springy') in a fall.

Thanks for the reminder, outofmytree, to keep slack out of life support. ... rep'd