I have done this a number of times and, yes, I feel the advantage just like the rest of you. I am just not sure it is 3 to 1. I use all three of these setups almost every time I climb. I almost always use both SRT and DdRT in a good climb and I carry that homebrew QuickRoll every single climb for just what the drawing shows. But I am a curious type and like to know why there seems to be a difference. I see the factors that don't change at all, like the total rope used, how much the climber moves for the amount of rope in total (these are not mere beliefs but witnessed fact), and I have a fuzzy time reconciling that with the simple truth that you and I feel. I am not disputing the math changes somehow. I feel it same as you. But I ask a specific question in that previous note. Can you tell me how?
You may be over-thinking this.
I gotta try that out
Boy, have I got something funny to tell you guys about that! Ellen (wife) went to the three day camping/climbing event with me, the one where we sat thru the talk on MA I mentioned with Mumford, Dave from WesSpur, etc. Now, even looking at these equations above, one can still wonder exactly what the real picture is, to actually visually see why it is different for the groundie. And it was her that told me! We were sitting in bed last night after that all this discussion and I visited with her about it since it was still on my mind. In the middle of talking about it, she remembered something I had not. She said, 'what about when they put the groundie up in the air?'. And of course that is the true picture! It is the 2:1 that does not actually exist! It is always 3:1 even with the groundie! And the cheating, magic part is we add a bit of weight to the groundie to keep him on the ground. In the drawing, if the groundie weighs exactly half what the climber weighs, that is the only way he can hang in the air and not drop. It looks like 2:1 when he stands on the ground but that is because we hand him a feather to overcome the friction in the pulleys! Without pulley friction, we could walk over and just touch him with a finger to move him up or down and the climber would move opposite. It looks like 2:1 but the groundie is always one third part of the load. He is one third of total load at the tip even when he is on the ground pulling; he simply always has added weight. You would never have a groundie lift a climber in the drawing if he weighed half or less what the climber weighs. If he weighs half, and you have friction less pulleys, he lifts both himself and the climber an equal amount, which is half what the climber would rise if you reach up and hold the groundie still, where he is hanging. This where we get an apparent 2:1 with a groundie. And it takes no extra force. We just cheat a bit and make him heavier all the time so only the climber part of the load rises and that is the only part we care about.
Am I the only one here on the Buzz who has ever high-jacked a thread to clarify something? To discuss and analyze climbing systems is exactly what our TreeBuzz forum is in large part concerned with, isn't it? OK, so wrong thread right here, my apologies once again, in case you missed it the first time.
Gotta say Samson's guides (written on their site & the corresponding Youtubes) were all I needed for nearly perfect splicing of an entire climbing & heavy-duty rigging kit....Combine this approach with Wesspur's clearance section and you can have a $1k "retail" rigging kit for well under half the price!
The APTA is one of the few tools that I can honestly say was a total game changer for me...Being able to set access lines in excess of 200 ft has made my life soooo much easier. Some of the best money I have ever spent on a piece of tree gear.
But my wife is a physicist...
Wesspur has some good YouTube videos on splicing. Lookup class one double braid eye splice and 16 strand eye splice. I just use home made wire fids for everything. You can look up a fid lengths on Sampson's Fid Length Chart .
