What would you do?

Post by **StephyG** » Thu Apr 03, 2003 7:35 pm

The way I understand it, and please correct me if I'm wrong, is that if you have three anchors to run the rope through, the resulting rope angles will be 2 > 90 degrees and 1 (the top one) > or = 90 degrees.

With just two anchors you have two rope angles that are 90 degrees.

With that in mind would a three bolt unequalized anchor reduce the effect of the European death triangle?

Post by **Legion** » Thu Apr 03, 2003 7:37 pm

Do you have a deadline? I have a picture of the bolt museum at Stone that might be usefull to you. I could scan it this weekend. Also check out the ASCA site! Too bad I just pitched a bunch of REALLY manky fixed gear that used to be an anchor at one point.

Post by **Eric** » Thu Apr 03, 2003 7:47 pm

Muao Dib,
In this case only the top anchor would be load bearing and the angle there would be <5 degrees. With just two anchors that are on the same horizontal plane (i.e. 180 degrees) the angle on each would be pretty close to 90 degrees and would result in the "Death Triangle". For rappelling this is usually okay on bomber anchors, but any other time would be a very bad idea!

Legion,
My class meets in two weeks so any pictures you have would be nice, but don't worry to much as I already have a few. Variety is always nice though.

Post by **Legion** » Thu Apr 03, 2003 7:51 pm

The top bolt is essentially holding all of the load. If it fails and shockloads the two lower shuts (in pseudo-american death triangle config) the forces are going to be high enough to make me think its safer to put your trust in the two lower ones rather than risk having the top bolt fail. Or just equalize them. In granite I don't see as much of a prob, but setups w/o chains really tweak bolt holes in sandstone. Not to mention the shuts. Anyone want to venture to make a calc of the forces generated in a situation where the top bolt fails?

Post by **StephyG** » Thu Apr 03, 2003 7:53 pm

Ahh I see. However, the angle won't always be less than 5 degrees, it depends on how high it is above the bottom two and how far apart the bottom two are.

There is a cool picure of some equalized beaks and heads in the photo gallery under Pets. You may want to use that one. It's title is something like "sit, now stay".

Post by **Legion** » Thu Apr 03, 2003 8:01 pm

how about the infamous RURP belay... on Jolly Roger, I think??? Or was it S of Dreams? Am I close?? (batguano???)

Post by **loren** » Thu Apr 03, 2003 8:09 pm

I take it back

Post by **StephyG** » Thu Apr 03, 2003 8:11 pm

Batguano is on his way to the fisher towers to grovel in the mud with Horatio.

Post by **Andrew** » Thu Apr 03, 2003 8:33 pm

how about the anchors on ro sham po. The angles aren't as severe as in the picture you provided. Is it best to use all three or just two. It seems to be on Ro that it would be better equilized.

Post by **Eric** » Thu Apr 03, 2003 9:05 pm

In my opinion, it would almost always be better to use all three for lowering since the outer two are used during normal top roping which is where most wear and tear come from, using all three (with most of the force going to the top anchor) uses the top anchor and doesn't wear a grove in the outer two when lowering. It would also decrease the amount of twists and kinks that are put in a rope by going through two anchors. And since you are not creating an American Triangle effect, it is better for the longevity of the anchors in general.