@@ADDekoning100 Thanks for clearing up the theoretical Mechanical Advantage (MA) for those who are not as informed. The thing is, in this system you're pulling on a (theoretical) 3:1 with a very inefficient 2:1, making a compound 6:1. I don't see that you get the extra 1:1 from the tail you're pulling on, just the 2:1 hauling on the 3:1 system (~6:1). The issue here is that the components used are not at all efficient, except for the pulley. The Ropeman at the anchor serves as Progress Capture and redirect, but does not have a pulley, so you have to drag the haul line over the cam, and around a tight bend, creating lots of friction. This brings the first system closer to 2:1 than 3:1. The separate 2:1 created by the short line goes around a carabiner, which creates lots of drag; this gives you closer to a 1:1 than the theoretical 2:1. Having one efficient pulley in the system is great, but taking into account the inefficiencies of the rest of the system, you probably don't get over around a 3:1 to 4:1 in the end.
there is no reason to pay the money and carry the weight to the the two ropeman, nor waste money on a VT Prussik, when you can make your own prussik from cheap 6mm cordage
The reason to buy a vt prusik is that you can used for things a 6mm cordage prusik can't deal. It can be used as a rapel device. Which you wouldn't want to do with cheap 6mm cordage (won't melt due to aramid sheath) . VT prusik also grabs better due to the increased friction from having less core (flatter). If you're only using the 6mm cord as a prusik that's fine, but a vt can out perform it in many other ways.
Agreeing with everything Lok MTB said. The VT also releases under tension if it’s tied above the rappel device, whereas most other prusiks would lock down and be extremely difficult to release if weighted. This allows you to maintain more control of your rappel by keeping your rappel device right on the harness itself instead of having to extend it on a sling while you load the prusik below the rappel device. From what I’ve seen, people tying autoblocks below their devices end up spending (wasting) more time tying and retying it to get the friction setting right, only to have it STILL tighten up or be too loose mid-rappel. The VT is a fantastic device.
nice video
but - to get the best efficency its better to put the pulley close to the hauling section
Nice!
That is not a 7 to 1
Looks like 5 to 1
I think it's a 2:1 pulling on a 3:1 which is 6:1
@@ADDekoning100 Thanks for clearing up the theoretical Mechanical Advantage (MA) for those who are not as informed.
The thing is, in this system you're pulling on a (theoretical) 3:1 with a very inefficient 2:1, making a compound 6:1. I don't see that you get the extra 1:1 from the tail you're pulling on, just the 2:1 hauling on the 3:1 system (~6:1).
The issue here is that the components used are not at all efficient, except for the pulley.
The Ropeman at the anchor serves as Progress Capture and redirect, but does not have a pulley, so you have to drag the haul line over the cam, and around a tight bend, creating lots of friction. This brings the first system closer to 2:1 than 3:1.
The separate 2:1 created by the short line goes around a carabiner, which creates lots of drag; this gives you closer to a 1:1 than the theoretical 2:1.
Having one efficient pulley in the system is great, but taking into account the inefficiencies of the rest of the system, you probably don't get over around a 3:1 to 4:1 in the end.
there is no reason to pay the money and carry the weight to the the two ropeman, nor waste money on a VT Prussik, when you can make your own prussik from cheap 6mm cordage
The reason to buy a vt prusik is that you can used for things a 6mm cordage prusik can't deal. It can be used as a rapel device. Which you wouldn't want to do with cheap 6mm cordage (won't melt due to aramid sheath) . VT prusik also grabs better due to the increased friction from having less core (flatter). If you're only using the 6mm cord as a prusik that's fine, but a vt can out perform it in many other ways.
Agreeing with everything Lok MTB said. The VT also releases under tension if it’s tied above the rappel device, whereas most other prusiks would lock down and be extremely difficult to release if weighted. This allows you to maintain more control of your rappel by keeping your rappel device right on the harness itself instead of having to extend it on a sling while you load the prusik below the rappel device. From what I’ve seen, people tying autoblocks below their devices end up spending (wasting) more time tying and retying it to get the friction setting right, only to have it STILL tighten up or be too loose mid-rappel. The VT is a fantastic device.