T3WP as progress capture?
Posted: Mar 31, 2012 8:25 pm
This subject came up recently, and frankly it has me a little baffled. Apparently some cavers and responders are being taught to always use tandem 3-wrap Prusiks for progress capture on the haul line, just like you see on a T3WP belay.
Like this:
\
Apparently their rationale for progress capture always being T3WP is that it's your life support line. I was also informed the only NFPA certified cave rescue technician course in the nation teaches it this way.
I admit I'm more used to the standard 3-wrap Prusik progress capture I see used everywhere in haul systems, including NCRC:
Call me curious, but I'm trying to figure out why anybody would require tandem Prusiks for progress capture.
My understanding is the reason for the second Prusik (furthest from anchor point) is to catch a severe shock load by backing up the first Prusik which may slip/glaze when sudden, high force is applied. Perfect for the belay line, but a little redundant/inefficient for the main line which presumably has a team of people hauling on the end anyway. Tandem Prusiks on both main and belay do make the systems more interchangeable, but the need to switch roles during a raise or lower seems pretty unlikely.
Comments from any of you other cave/technical rescue people out there?
Like this:
\
Apparently their rationale for progress capture always being T3WP is that it's your life support line. I was also informed the only NFPA certified cave rescue technician course in the nation teaches it this way.
I admit I'm more used to the standard 3-wrap Prusik progress capture I see used everywhere in haul systems, including NCRC:
Call me curious, but I'm trying to figure out why anybody would require tandem Prusiks for progress capture.
My understanding is the reason for the second Prusik (furthest from anchor point) is to catch a severe shock load by backing up the first Prusik which may slip/glaze when sudden, high force is applied. Perfect for the belay line, but a little redundant/inefficient for the main line which presumably has a team of people hauling on the end anyway. Tandem Prusiks on both main and belay do make the systems more interchangeable, but the need to switch roles during a raise or lower seems pretty unlikely.
Comments from any of you other cave/technical rescue people out there?