The other day I walked into the studio (Neverland) armed with one goal for the morning... build a system that is
- Efficient in Gear
- Efficient in People
- Efficient in Physics
- AHD Based
- Small Team Based
- One Person Load
- Very Reproducible
- Raise Only Based (but with a margin of error that allows for downward adjustments... i.e. lowering)
Now bear in mind, that within Neverland (RLA rigging and film studio), we are still in TI mode (tenant improvement)... we still have a huge amount of tweaks still to be made. One of these tweaks is a "protector" over the door into my office. So while the system is assigned for a predictable vertical terrain and horizontal top side... I did need to build a dynamic directional to keep the one person load from gouging my office door during the raise.
I started with a basic monopod or gin pole configuration. I used a tri-guy configuration. The exercise wasn't so much about the AHD as much as the mechanical advantage system being used. That said, we are a huge advocate for AHDs when and where possible... so in staying connected with this vision and goal... for me at the time, the monopod worked well. I used the gin pole head of the Arizona Vortex because I purposely wanted some height, however... I could have easily used the SMC Vector for the same thing and rigged in the same fashion. Keeping the guying angles to roughly 30° and erred forward a bit. I used twin Petzl Pro pulleys at the head of the Vortex gin pole (these pulleys swing side plate designs and are 95% efficient). Everything was a quick set up in terms of time and effort. In later projects we will most certainly be covering the rules of thumb for setting up high directionals of major 3 variants; easel A-Frames, SA Frames and Monopods/gin-poles.
My vision for this exercise was set for a small team-small party rescue.
The call area is a "known rescue area". We have trained somewhat extensively here and we know (more or less) what we can take and leave behind in terms of gear. Because our SOPs standardize on the two tension rope systems and very likely the rescue to be performed will be a standard "rig to raise" with no attendant (as he/she will descend to the patient on a separate line and move up with the patient "separately". No need to complicate things when unnecessary.
We opted to use a "ganged on" mirrored In Line 9 mechanical advantage system. The Petzl Jag System, attached to the haul line and terminated at the rope coming out of the Petzl I'd at the anchor. This is a valuable tool for backcountry and industrial teams, with an eye on time, energy and efficiency (and as with all complex MA systems...) you'll be doing a fare bit of resets. The resets are super simple, but remember for every 9 feet hauled... you gain 1 foot. It is an exchange of currency for sure.
The twin technical rope rescue system is 2 x 9:1... yes... that is an ideal mechanical advantage of 18:1. Now are we getting that?... No; but I can guaranty that one person can do this... so having a standard 2 person haul for small team rescues is a breeze. And yes... I did use a combination of rope grabs... I used the Petzl Rescucender on one end and the Petzl Tibloc on the other. Could I have gone with only Tiblocs? Yes. Could I have moved the Tibloc to the front and moved the Rescucenders to the I'd side...? Yes. And do remember that we are sharing a one person load between two ropes and one critical component is the tail-end coming out of the Petzl I'd (when using an in-line 9 MA system). The Petzl Tibloc works best when tensioned on both sides of the device, but since that is not the case coming off the I'd, there is a critical point to consider and I was fine with it as the load is shared between the 9:1 system (x 2)...
A few people have asked about using a CMC MPD instead of the Petzl I'd. I am personally more comfortable with lighter loads using the I'd. The MPD is heavier to carry and as a wise man told me..."nothing in life is free". The MPD, while being extremely efficient as a pulley.. is not a convincing tool for my extrication exercise. Yes, it is an amazing tool, but it's usefulness here compared to the advantages I have everywhere else is not enough to warrant me using it. That said, if I had a two person load and all other things being equal... then it would most certainly be a consideration.
So two things left... being easily reproducible and having the ability to go down (if the initial plan to raise only went a bit sideways). Systems don't get any easier than to "gang on" a hauling system. As the video in this link shows... drop the line, connect the MA system and haul. Things are pretty minimal at that point. Are they heavier?... no, because they include the same gear you'll be using to build something else. And what about "down down"? Remove the Jag System and you are now in lower mode.
Peace On Your Days,