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Adam I would ask the manufacturer(s) about your concern/situation. In good conscience, I can't agree with what you want to do without discussing it first with the manufacturer(s).

The Joker is rated as such because the strand has been proven to meet the requirements of all 3 tests.

Yes, there are strands meeting both half & twin certification & this site has discussion about using methods; but it's based on manufacturer input about their respective product.

I match my intended climbing method with the proper certification keeping each pitch independant.

Thanks for the responses guys.

I've emailed BW and we'll see what they say. But, here are some of the numbers I've been looking at. Just makes me wonder what the differences are?

Model-------------UIAA Falls--------------Impact Force

PMI Verglas (18)twin--(8)double -----8.9kn twin--5.2kn double

BW Ice Floss (19)twin--(?)double -----8.9kn twin--? double

Beal Joker (25)twin--(20)double-----9.5kn twin--6kn double

P.S.I did find out that it's not recommended=bad (per Beals web site) to have 2 followers (one climber on each rope) with twins.

Adam, certainly worth asking, what does the double/half certification standard serve?

Climbers potentially subject these strands individually to larger falls than singles by using greater protection intervals on vertical ice/alpine. Why are they also not measured using single cert perameters, mainly the falling mass?

I can tell you that 8.9 is a pretty high impact force, that said I have climbed(and fallen) using double ropes as twins and am still standing. You have the ropes, and you are going to use them. Climbing with double rope technique on a twin rope does not sound safe to me, I would say just use them as twins. Your impact force is a bit higher, but you can compensate for that with a dynamic belay and screamers. You can't make the twin rope stronger, and catching a leader on a single 8mm rope can be sketchy.

Personally I would be more concerned with the different static elongation of the two ropes when rappelling.

I picked up a pair of the Verglas recently, and plan to use them this weekend. I know they are rated for twin AND double techniques, but have a question on practical usage...

Is it wise to mix and match alternating or shared clips on a single pitch? For instance, if one rope is clipped all left AND the other is clipped all right, and then you clip them together - in theory that shared carabiner will get triloaded.

Thoughts?

One alleged theoretical disadvantage to mixing double and twin rope technique is the differential movement of the ropes when suddenly weighted. This supposedly can melt the ropes and potentially result in rope failure. Triloading carabiners where you load across the weaker axis is probably not recommended either. As an average climber, I've not heard of this differential movement resulting in rope failure, but I have heard of biners loaded in the short axis failing.

Twin ropes are designed to be used as pairs. They have great resistance to cuting over edges, (great for alpine climbing) when paired and are LIGHTER than doubles.

If you want to clip alternative points of protection then use doubles.

John McNamee wrote:Twin ropes are designed to be used as pairs. They have great resistance to cuting over edges, (great for alpine climbing) when paired and are LIGHTER than doubles. If you want to clip alternative points of protection then use doubles.

But what about a rope like there Verglas that is rated for both? Practically, how does one use them? Climb each pitch in a certain style OR mix styles on a pitch?

Leo's points are good ones - indicating perhaps it is best to select a certain style for each pitch.

From the perspective of an average climber, with Verglas ropes I'd select a technique for each pitch; however, for me that'd be whichever technique I'd have clipped/committed to with my first piece of gear. Addendum: while fishing with my daughter today, I remembered you can hedge your bet by clipping 2 slings to the first piece(s) until you commit to either technique.

FWIW, one old buddy of mine sometimes used doubles as twins (accepting the slight weight disadvantage), but he'd pull up one rope to climb a difficult clip and then bring up the other rope to get both clipped. His thoughts were that that reduced the fall he'd take if he blew the clip just as he pulled up the rope. He liked the extra sliver of security knowing he had slightly fatter ropes (8.5mm, Mammut, 10-12 years ago).