Double Overhand Knot for rigging

[Ship-badger]

I recently saw a Double Overhand knot used to join two ropes to lengthen one side of a Y-hang. I questioned its use in this situation, and it was explained to me that the knot is used regularly to join two ropes together for abseiling. I knew this. I pointed out that we weren't joining ropes for an abseil. I have read a few reports showing how well this knot is suited to retrievable abseils, but this hasn't convinced me that it is suitable as a method of joining ropes for rigging. How does the knot perform in drop-tests? Do we have any data? I couldn't find any on a quick web search. I'll be sticking to my Double Fishermans or Capucin and Double Fishermans.
Your views and opinions please.

 

[Stu]

Can you explain where it was joined? I'll presume that the rope was tied to the first bolt of the pair that would form the y-hang, and found to be too short. The second rope was attached here? Then the y-hang was continued as normal?

If every bit of rope had to count (or else you'd terminate at the first bolt of the pair, no?) then it's not the worst knot to join,but since the common concensus is to tie two overhand knots back to back,  that would be more wasteful than using a better knot (double fisherman's as you mentioned or figure of eight bend).

It's arguable that if a bolt failed and the knot was loaded, a certain amount of rolling wouldn't be a bad thing (if tied with two overhands back to back) but unnecessary.

Not sure what I think really. Might be inappropriate rigging but as long as it couldn't flip and come undone if loaded, it wouldn't jangle my nerves. That would come from the fact that it's inappropriate! 😊

 

[Ship-badger]

The knot was in one arm of the Y. If the other arm had failed, what might have been the result of the shock load, slight as it may have been, on the Double Overhand knot? I was concerned enough to question its use, but not so concerned as to refuse to use it. My concern was more that it was inappropriate, as you have said.
When used in the mountaineering abseil retreat situation the knot is unlikely to be subjected to a shock load; but in a rigging situation it might well be.
I'll not be adopting it myself; but do any of you use it for rigging?

 

[Stu]

Ok, so it was as I described, cool. Just so we're on the same page, when you say double overhand it's this - two strands parallel and a an overhand tied? As I mentioned before it's now common for a second double overhand to be tied close up to the first knot to avoid flipping. If only one knot was used to join I'd like a fair bit of tail to negate flipping being a problem and with just the one overhand I'd worry about it flipping. Needlesports website has some good information and data.

To me sounds like showing off for its own sake.

 

[Ship-badger]

It was two Overhand Knots tied very close together, and it did have a fair tail on it.

 

[Stu]

I'd live with it but it's not what I would use. There's a case for the tails dangling down and being potentially confusing for someone clipping onto them on what would be an open end of rope...

 

[Madness]

I can't see the point of doing it that way, unless you are really short of rope. I would have started the Y-hang with the next rope or at a push terminated the first rope in the Y-hang with a Figure of 8 loop with a krab. Into this krab I'd put an Alpine Butterfly one side being the live rope the other going to the second bolt of the Y-hang - If you get what I mean.

 

[sambo]

Stuart makes a good point in regards to the long tails. A friend of mine died last year after rigging a retrievable abseil using an overhand knot, and putting one of the long tails through his belay plate. He then loaded the rope and the inevitable hapened. I make a point not to use overhand knots for anything that is safety critical.

 

[Madness]

Stuart makes a good point in regards to the long tails. A friend of mine died last year after rigging a retrievable abseil using an overhand knot, and putting one of the long tails through his belay plate. He then loaded the rope and the inevitable hapened. I make a point not to use overhand knots for anything that is safety critical.

I think your friends death should highlight the need to test load an abseil whislt still clipped into something solid with either a Cows-Tail (caving) or a Sling (climbing)
Regardless of the type of knot used you need to be alert 100% of the time and not take it for granted that yourself or the people you are with have done stuff correctly. Everyone is human, and humans f*ck up sometimes.