Back up knots

[PUClimber]

I was checking out the secret weapon post and was noticing there are two alpine butterflies underneath the prussik. Is the alpine butterfly an acceptable back up without locking it off with a carabiner. If so what other knots are acceptable to use with out having a carabiner in there or should they all have a biner in them?

 

[Norm_Hall]

[ QUOTE ]
I was checking out the secret weapon post and was noticing there are two alpine butterflies underneath the prussik. Is the alpine butterfly an acceptable back up without locking it off with a carabiner. If so what other knots are acceptable to use with out having a carabiner in there or should they all have a biner in them?

[/ QUOTE ]

An alpine butterfly is not a slip or rolling hitch, so therefore it is acceptable without having to use a carabiner to lock it off. For that application, I think the alpine butterfly is the best suited knot.

 

[PUClimber]

Thanks Norm.... Alright so can you back up a prussik on a single line with just an alpine butterfly?

 

[tod_k]

Think about ONE of the legs getting pulled by some sort of force like a skid steer stumper etc. What would happen?, will the back up work?

 

[PUClimber]

I don't follow you Todd. I thought the backups were in case a friction hitch or climbing knot would slip?

 

[tod_k]

Thats right. What would happen if one leg of the rope got pulled. One knot would push the prusik up right? While the other went down. Knot sure how good of a back up it is. Get it "knot".

 

[TLHamel]

[ QUOTE ]
Alright so can you back up a prussik on a single line with just an alpine butterfly?

[/ QUOTE ]

Yes.

One advantage I see to using the secret weapon SRT is that it affords you an almost immediate descent in case of emergency while ascending. Same while ascending DRT. However, with SRT I don't believe the weapon saves time.