Anchor Point Question
Force calculator:
http://www.myoan.net/climbart/climbforcecal.html
http://www.myoan.net/climbart/climbforcecal.html
The theory of evolution is just as stupid as the theories of gravity and electromagnetism.
Saxman, unless I'm missing something, that fall calculator is a piece of shit. If I tell it the rope is 100ft long and I'm 5ft above my last piece (10ft fall), it tells me I have a fall factor of 1.05! In fact, I can't get it to give me a fall factor less than 1.
Use this one instead:
http://en.petzl.com/petzl/SportConseils ... ctivite=14
@Gaar:
I don't know where you're getting the 20kN figure from either I'm afraid. Maybe I just don't understand what you're trying to say, but it sounds to me like you're saying that if a 225lb person falls 10ft, their anchor is going to experience upwards of 20kN worth of force. If that is true, then trad gear is WAY under-engineered...
I think you might be neglecting the significant amount of energy absorbed by the rope...or maybe you climb on static line
[edits] Having trouble with the URL.
Use this one instead:
http://en.petzl.com/petzl/SportConseils ... ctivite=14
@Gaar:
I don't know where you're getting the 20kN figure from either I'm afraid. Maybe I just don't understand what you're trying to say, but it sounds to me like you're saying that if a 225lb person falls 10ft, their anchor is going to experience upwards of 20kN worth of force. If that is true, then trad gear is WAY under-engineered...
I think you might be neglecting the significant amount of energy absorbed by the rope...or maybe you climb on static line
[edits] Having trouble with the URL.
Once again. Top rope force cannot exceed a more than about a 0.75 fall factor depending on the rope you are using. You can check all the calculators every one has put up. They will all show this. And really without hitting the deck you can only have about a 0.60 fall factor with 99% of the ropes out there.
The most force an anchor will see is about 11 kn. And this is VERY extreme!
The most force an anchor will see is about 11 kn. And this is VERY extreme!
http://www.foxmountainguides.com
BJ........Did you even bother reading my last post?....
Karsten, I agree with you achiving a Fall Factor of 2 is impossible on TR, BUT it is very possible to achive ~4500lbs. You should now as well as I, that short climbs (<30ft) are very common in guiding; shorten the rope, lessen the stretch=more weight on the anchor.
I dont really think I could have made it any more clear then my last post.
And just to make sure I was doing things right I called Alan Jolly (one of the founders of AMGA and PCIA) and asked him to check it before I posted
Karsten, I agree with you achiving a Fall Factor of 2 is impossible on TR, BUT it is very possible to achive ~4500lbs. You should now as well as I, that short climbs (<30ft) are very common in guiding; shorten the rope, lessen the stretch=more weight on the anchor.
I dont really think I could have made it any more clear then my last post.
And just to make sure I was doing things right I called Alan Jolly (one of the founders of AMGA and PCIA) and asked him to check it before I posted
"climb, fall, send, go home"
Yeah, man, I read it. I just don't get it. Like I said, maybe I just don't understand what you're saying, so I'm going to need some help.Gaar wrote:BJ........Did you even bother reading my last post?
1.) I don't know how you arrived at your numbers. The "sloppy math" is too sloppy for my tastes. Look, for all I know the numbers are right, they just seem way too high for me (and others apparently). 20kN (a figure VERY close to the maximum rating of most biners) seems dubiously high to me, especially on top rope (even with a 10ft fall).
My knowledge of physics goes little beyond F=ma so maybe you could explain how you arrived at 2250lbs?Gaar wrote:A 225 lb person falls 10 ft which = 2250lbs on the climber side.
2.) If long TR falls can approach 20kN, then what about lead falls?
I'd think the forces there would be higher than in any comparable TR fall. This is why I mentioned falling on trad gear. If you're telling me a 10ft TR fall subjects an anchor to upwards of 20kN of force, how much force would a 10ft lead fall put onto, say, a bomber #2 cam (rated to 14kN)? Last I heard, people are taking 10ft falls onto cams and they weren't breaking...unless they're Aliens.
3.)
I'm holding onto hope here that you'll explain your argument in greater detail, but statements like that aren't encouraging.Gaar wrote:Karsten, I'm not talking about fall factors, I'm talking about froce!
If Alan agreed with you then he is mistaken as well. I have run this by a few others(of which names I need not throw around), and in the testing that we have done I stand by my comments. 11kn on a toprope anchor is an extravagant amount of force that would be hard to attain.
http://www.foxmountainguides.com
Gaar's numbers might be accurate if you use a static line and have the belayer anchored to a fixed point. Even then I'm skeptical.
As for normal climbing rope, I still stand by my original statement: even with a fall factor of 2, my fat ass doesn't break 12kn. For a top rope fall factor I think the max would be about 9kn, and that would be falling from the top and just barely not decking.
As for normal climbing rope, I still stand by my original statement: even with a fall factor of 2, my fat ass doesn't break 12kn. For a top rope fall factor I think the max would be about 9kn, and that would be falling from the top and just barely not decking.
That I would be more inclined to believe. It definitely seems like he's ignoring the energy absorption capabilities of dynamic rope, which is strange because he gives due credit to knot tightening, rope slippage, and energy absorption by the body.Shamis wrote:Gaar's numbers might be accurate if you use a static line and have the belayer anchored to a fixed point. Even then I'm skeptical.