Two rope lowering systems

[Always_learning]

Hello All,
I'm keen to hear everyones thoughts on two rope lowering systems, the pro's versus the con's.

This has come up because with the new MPD I see that to use it as a belay device, it must be rigged in tandem (recomended with another MPD) so that both devices are sharing the load.

This got me thinking on how many teams out there actually rig this type of system?

Look forward to the responses,

[jdcalamia]

By two ropes are you referring to a main and belay, or two main lines such as in a dual rope highline? I would imagine nearly all department's are requiring two rope systems (main and belay). However, I think SRT has it's place and merits in certain situations (minimal manpower, either minimal by training or by shear numbers). In some smaller departments who don't have a dedicated rescue company, there may only be a few rope savy guys and who's to say they are all working at the same time. Might just be one rope guy working with minimal numbers of inexperienced members, this is the perfect scenario for SRT.

[ProgressiveRescue]

The use of two MPD is only a recomendation from CMC. The recomendation does however make sense. The thought behind it is that either rope system can perform either function, similarly, without the need for complex changeovers or function-specific equipment thus saving some time, increasing the safety margin, and overall I'd like to think making the operation a bit simpler.
Our team runs a lowering line (rack) and a belay line (540 or Tandem Prusiks)
There is chatter of giving these a try. I've used the Petzl I"D as a belay device and it's worked nicely. I love the fact I can lower with a belay line and I also don't need to worry about LRH's or MAS systems to off load the line should there be a belay catch.
Anyway I've gotten of topic...Hope this helps.
Stay Safe,
MIke Donahue

[jdcalamia]

What are your feelings about using the ID as a lowering device, then switching it to become the anchor pulley in a 3:1 raising system? I've used it a few times in training, and it seems to work only OK in a raise. With the friction that has to be overcome on the ID, it doesn't really seem to be a true 3:1.

[Always_learning]

Hello gents, thats what I'm referring to, two ropes both under tension.
Not like you would have when you use for example an ID as the DCD and TPB as the belay system, one rope is taught, the TPB is not until a belay event occurs.

JD, the ID is great as the COD 'pulley' and PCD in a 3:1 haul system but your right, the friction leaves allot to be desired...but in comes the MPD and the fact it does work as an efficient pully in this situation.

The MPD is a great device for sure but one we only use if we know we are going to be hauling, but our primary device for now is the ID.

Progressive, I agree the two rope lower is a recomendation for use on the MPD itself, I presumed the reasoning for this is because you cannot use the MPD in the same manner as say the ID, where you can tilt it and sandwhich it so to speak to belay with the device.

Try it on the MPD and it continually locks up, the only way you can use it as a belay is to use it in a tensioned, two rope system....unless someone has firgureded outa way to use it like the ID?

I'm all for tensioned two rope lowers but I understand this is outside the norm for your average Fire Dept Ropes team.

Thanks for the replies,

[stickboy42]

always:
this is what i believe you are referring to... seems to me that europe does much more of this 2 rope tensioned system work than we do. pretty much mirrored mainlines that back each other up and share the load between them much of the time.

-m

[ProgressiveRescue]

What are your feelings about using the ID as a lowering device, then switching it to become the anchor pulley in a 3:1 raising system? I've used it a few times in training, and it seems to work only OK in a raise. With the friction that has to be overcome on the ID, it doesn't really seem to be a true 3:1.

The ID is great as a belay and as a lowering device however I agree with you regarding the friction created when it is applied as an anchored pulley in a 3:1MAS. This is where the MPD would probably really shine. I'm sure like the ID the MPD may have it's cons however it's a great tool to throw in your toolbox. I think the only way to defeat most of the friction created when using an ID as an anchored pulley in a 3:1 application would be to hold it sideways as if you were belaying someone. With a heavy load I don't think that would work very well.
Stay Safe,
Mike Donahue

[servantleader]

Permitting the belay line to share part of the load on long lowers (> 30m) is a current hot topic of rope rescue R&D. I have been told that having both lines mirror each other on lowers (i.e. both act as tensioned lowering and belay lines) is under investigation. The developers of the MPD might have been looking toward this.

Maybe some useful background on the topic:
http://www.ikar-cisa.org/ikar.../200...s-Mauthner.pdf

[stickboy42]

We use it this way all the time. There was an article in last quarters TR mag regarding this very thing, comparing descent control devices worldwide that can be used in a raising system for progress capture. The I'D comes out highly ranked, in the high 60's for efficiency overall.. I'll try and find that article electronically so you can see it if you don't have TR mag yet... There is definately a noticeable increase in the initial friction used to overcome the static state. A common rig for us is to use a 9:1 batwing with the id prior to the 2nd throw (3:1)(1:1cd)(3:1) trying to have the 1st throw be 3x the 2nd so they two block at the same time.

-m

[ProgressiveRescue]

I'd love to read that article.
Thanks,
MD

[jdcalamia]

"Trying the True Belay" - FireRescue Magazine July 2010

[stickboy42]

here is the article that i was referring to:

http://www.itrsonline.org/Papers/200..._ITRSPaper.pdf

-mike

[FiremanLyman]

Hello gents, thats what I'm referring to, two ropes both under tension.
Not like you would have when you use for example an ID as the DCD and TPB as the belay system, one rope is taught, the TPB is not until a belay event occurs.

We prefer using a duel tension rope system for lowers and often use munter hitches for the DCD (can't wait to hear from the "you must use hardware" crowd on that one). I feel comfortable with this for a single person load, and we are VERY well trained in this method. Have a piggyback MA (3:1 or 4:1) loaded with a Gibbs on it to haul on if the load needs to re-ascend.

But you can switch to a number of DCD's to accomplish the same thing- tandem prusiks, bar racks, figure 8, Petzel ID. Have not used the MPD, looks like it could have freezing problems like the 540 belay if not used under tension - am I correct?

[jdcalamia]

Not throwing stones at your operation, but how do you guys get your systems to pass a whistle drop test using the munter? Just curious as to how you guys overcome this.

[servantleader]

Systems relying on dual munters only cannot possibly pass the whistle test.

Also, there is a (reported) superior "non-hardware" DCD alternative to the munter: the "super munter". The "super munter" is reported to not twist the rope like the munter and provides substantially greater control of the load.