Radium Release Hitch

[NZcaver]

How well does the I'D withstand mud?

Not well at all! nor does the 540. Both great devices, but not for cave rescue.

He, he, he... I was waiting to see how long it would take to be shot down on that one. And sure enough, you guys took the bait! You're not wrong, of course.

[Stridergdm]

How well does the I'D withstand mud?

Not well at all! nor does the 540. Both great devices, but not for cave rescue.

During my Level 3 class, we had to setup a highline between two trees (fairly close to the ground). Being a bit perverse I handed a 540 to one of my teammates and encouraged him to use it.

He did. Not something I'd normally suggest doing, but since we'd been avoiding it all week figured it was time for us to get a little experience with it.

And I think we got just enough experience to decide not to use it again.

[Stridergdm]

Just for the record I passed this on to some other committee members and one word that was passed back was to suggest folks read test report that Kirk and Katie did on the RLRH.

I haven't looked for it myself, but will at some point.

[NZcaver]

During my Level 3 class, we had to setup a highline between two trees (fairly close to the ground). Being a bit perverse I handed a 540 to one of my teammates and encouraged him to use it.

He did. Not something I'd normally suggest doing, but since we'd been avoiding it all week figured it was time for us to get a little experience with it.

And I think we got just enough experience to decide not to use it again.

The 540 worked OK for us last year (but we didn't try it with mud). Here's the video.

Hey - remember that highline we built over the pond down in NM? We kept dunking Chris and cooling him off.

[Tim White]

Just for the record I passed this on to some other committee members and one word that was passed back was to suggest folks read test report that Kirk and Katie did on the RLRH.

I haven't looked for it myself, but will at some point.

That report is titled: Release Devices: A Comparative Analysis

[Stridergdm]

Thanks Tim.

Do you have any idea on where it can be had?

[Carl Amundson]

Thanks Tim.

Do you have any idea on where it can be had?

Here you do:
http://www.riggingforrescue.com/rfr/publications.htm

The cost is $20

[Stridergdm]

Thanks Tim.

Do you have any idea on where it can be had?

Here you do:
http://www.riggingforrescue.com/rfr/publications.htm

The cost is $20

Thanks. May have to spring some money free.

For a few comments on it btw, Quick Discussion. Some may recognize the name of the poster there, Robert Riversong.

[fuzzy-hair-man]

I've been meaning to ask for a couple of days and it seems to be stating the obvious but a Radium Release Hitch looks just like a jigger 3:1 (all be it using inefficient pulleys) with a Munter on the end. Given this aren't your level 1s already learning a jigger just they don't know it yet? and if so I'd have thought they might as well learn a jigger and a Munter hitch and the Radium Load release as a specific application of the two of these.

I'd argue learning the components making up the Radium Release hitch (3:1 and Munter), rather than learning these each separately is a better approach to learning as there is less to remember and your giving them a more flexible approach and knowledge base to work from which could be important when the (I've always wanted to use that smiley).

Am I missing something? Does a jigger usually have a set mechanical advantage? Are you loath to call them the same thing because a RLRH supports full weight without backup (AFAIK) but a jigger doesn't get used without a backup? a RLRH uses 8mm cord right? but a jigger could use almost anything. Or is learning this way a historical thing?

BTW for self rescue I've read a lot about the Stop being used as a PCD with the benefit that it is also releasable under load, the downside is friction and if you workout the load on your anchors and the stop with a rescue load of 200kg it comes very close to the maximum load of the Stop (see LOAL) so for this reason the technique is probably limited to single person loads, but given (here in Aust. anyway) there's a high chance of someone on the trip having a Stop it seems a worthwhile self rescue technique to learn.

[Stridergdm]

I've been meaning to ask for a couple of days and it seems to be stating the obvious but a Radium Release Hitch looks just like a jigger 3:1 (all be it using inefficient pulleys) with a Munter on the end. Given this aren't your level 1s already learning a jigger just they don't know it yet? and if so I'd have thought they might as well learn a jigger and a Munter hitch and the Radium Load release as a specific application of the two of these.

Not really. A jigger really tends to refer to a 4:1 (or 5:1 depending on orientation) haul system comprised of two double pulleys (you can do it with 4 separate pulleys but you lose efficiency as the pulleys are on an angle) that can be used to haul or lower.

The amount of friction (which is a design feature) of the RLRH precludes its use as a haul system.

I'd argue learning the components making up the Radium Release hitch (3:1 and Munter), rather than learning these each separately is a better approach to learning as there is less to remember and your giving them a more flexible approach and knowledge base to work from which could be important when the (I've always wanted to use that smiley).

Nice smiley!

And I'd agree that knowing the 3:1 and Munter is fairly important.

Am I missing something? Does a jigger usually have a set mechanical advantage? Are you loath to call them the same thing because a RLRH supports full weight without backup (AFAIK) but a jigger doesn't get used without a backup? a RLRH uses 8mm cord right? but a jigger could use almost anything. Or is learning this way a historical thing?

Correct, a jigger usually has a set mechanical advantage.

BTW for self rescue I've read a lot about the Stop being used as a PCD with the benefit that it is also releasable under load, the downside is friction and if you workout the load on your anchors and the stop with a rescue load of 200kg it comes very close to the maximum load of the Stop (see LOAL) so for this reason the technique is probably limited to single person loads, but given (here in Aust. anyway) there's a high chance of someone on the trip having a Stop it seems a worthwhile self rescue technique to learn.

Agreed. And you make an important distinction between rescue vs single-person loads as well as self-rescue vs. a call-out rescue. Speaking from the land of lawyers, what you do to rescue yourself can't get me sued. But if I'm called in to rescue you, I'll try to stick to proven techniques as much as possible since it's a lot easier to defend if a lawsuit comes up. For example, given the subject at hand, if someone used a jigger in the place of a RLRH for a belay line and the belay line is shockloaded and a pulley in the jigger fails, the first question a lawyer is going to ask is, "What evidence did you have that a jigger would work in that situation?"

[tncaveres]

We did learn how to build jiggers last yr in level 3 . We used them as traveling haul systems.

[fuzzy-hair-man]

Not really. A jigger really tends to refer to a 4:1 (or 5:1 depending on orientation) haul system comprised of two double pulleys (you can do it with 4 separate pulleys but you lose efficiency as the pulleys are on an angle) that can be used to haul or lower.

A 4:1 or 5:1 would seem to be a pretty easy extension from a 3:1, and I'd say that a mechanical advantage system is still the same system even if all that advantage is eaten up by friction, it's still the same beast whether you construct it with carabiners, maillons, or pulleys. Perhaps teaching MA pulling systems and then the jigger and RLRH as specific applications of these??? This way perhaps keeping the two separate?

The amount of friction (which is a design feature) of the RLRH precludes its use as a haul system.

It's still the same basic structure though, and yes I recognised the friction as a design feature and the thing that probably lets the hitch survive the shock loads it's been tested with. People with nothing else still use carabiners to construct pulley systems though, Petzl's documentation for the Tibloc shows these as well as heaps of other materials.

Nice smiley!

For example, given the subject at hand, if someone used a jigger in the place of a RLRH for a belay line and the belay line is shockloaded and a pulley in the jigger fails, the first question a lawyer is going to ask is, "What evidence did you have that a jigger would work in that situation?"

Ron and NZcaver were suggesting connecting the haul directly to the anchor and doing away with the RLRH right? not as above where the RLRH is replaced by a jigger. (perhaps we are getting to a important reason to keep them separate which I suspect is what Stridergdm's example was subtly trying to show me. )

Which leads me to thinking if your haul team are inattentive or the message to them is late and they get the load stuck under a balcony or similar with the haul line pulled tight a jigger depends on being able to raise the load even slightly in order to let it back down right? (to release a PCD or put in a descender?) in this case that might not be possible, a RLRH would not be similarly constrained. Or am I wrong here?
Funnily enough the ukcaving board was dealing with a similar topic (but smaller scale) when talking about belaying etc with mini-traxions and the same problem came up there.

[Stridergdm]

Thanks Tim.

Do you have any idea on where it can be had?

Here you do:
http://www.riggingforrescue.com/rfr/publications.htm

The cost is $20

Thanks. May have to spring some money free.

For a few comments on it btw, Quick Discussion. Some may recognize the name of the poster there, Robert Riversong.

BTW, to quote myself (came across this topic looking for something else) I finally did pick this up and it's a great read. I highly recommend it.

[ljthawk]

Why carry a pre-rigged radium release when you can do the same with the rope and a tied off munter?

FYI, my "jigger" is a 3:1 / 4:1, found the extra pulley to make the 4:1 / 5:1 didn't add much with my cheaper CMI double pulleys; too much friction. Might have to fix that with some better pulleys.

L.J.

[Stridergdm]

Why carry a pre-rigged radium release when you can do the same with the rope and a tied off munter?
L.J.

I'm not quite sure I follow you. You obviously can't tie off your belay line since then it doesn't really work to well as a belay.

If you mean an additional rope instead, I'm not sure what you really again. Now, there is some debate going on if a munter is sufficient to control a rescue load, in which case one can argue a RLRH is less necessary.