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Old 04-18-2015   #1
 
England, UK
Join Date: Apr 2015
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Pulleys

Hey there

Any idea what spec of pulleys are needed as a minimum for rafting please? I'm thinking Z drags and the like of wrapped boats.

I have 2 Petzl Mobiles - breaking strength 15kN, working load 5kN. Will these be good enough, or should I try and replace them?

Thanks

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Old 04-18-2015   #2
 
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Denver, Colorado
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Hi

To me, that seems inadequate.

I note that least expensive pulley NRS sales has a "pulley strength " of 22kn or 4,946 lbs a number that is virtually the same as the large diamter spectra rope used in their pro throw bags....my pro throw bags rope muti task, as throw bag and z drag line, hence I only use pectra ropes.

Scott
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Old 04-18-2015   #3
 
Rockgizmo's Avatar
 
Colorado Springs, Colorado
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I'm not expert by any means.

I was in the same situation setting up my z-drag kit. I ended up going with a 32kN pulley. I didn't want the pulley to be the weakest link in the system.

I have had a few experiences setting up low ropes course (static line) or slack lines. I've seen a failure of a system and just to let to let you know its wicked. It was never the rope or pulley that failed usually a tree or webbing issue. Remember to put something like a pfd over the rope under tension this will help to absorb the released force if the system was to fail.
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Old 04-18-2015   #4
 
England, UK
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Thanks

I think i'm going to return them. I had Petzl fixes (23kn) before and they were fine when used in a wrap. My throwbag is rated to 17kN - I'd rather that be the weakest link. Although saying that, I'd imagine D rings would go first?
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Old 04-18-2015   #5
 
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Quote:
Originally Posted by eeonz View Post
Thanks

I think i'm going to return them. I had Petzl fixes (23kn) before and they were fine when used in a wrap. My throwbag is rated to 17kN - I'd rather that be the weakest link. Although saying that, I'd imagine D rings would go first?
Hi

In my swr class, were told d rings tend to fail at around 1,000 lbs...hence the need to use 2 or better yet 3 point load equalizing hitch on the raft.

Scott
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Old 04-18-2015   #6
 
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portland, Oregon
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pulleys rated for 20kn will support rope tension of 10kn if the rope is in line with the pulley (to and fro) larger pulleys with higher kn support larger rope. Rarely will a climbing pulley fail before the rope. I'd use 1/2" static for a raft and 3/8 for a kayak or ducky, unless dyneema rope, in that case it is a smaller diameter cord for the same rating. This std rope diameter will govern the size of the pulley
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