Screamers and Ice Screws?

[selkirk]

So what are peoples thoughts on using Screamers with Ice Screws, and about ice hooks?

 

 

[G-spotter]

Pound in ice pins in ice are next to worthless/body weight only. Testing reveals they blow out at about 5 kN, or more practically, less than the force that a Screamer or other load limiter limits the load to.

 

Thy are alright in frozen moss, mud, ice filled piton cracks etc. espcially if they are placed so they cam. Mainly because they are the only pro that will work in such situations.

[glassgowkiss]

This was published several times in magazines. this pole is kind of silly.

[selkirk]

Might be kind of silly to those of you with lots of ice experience. For me it's proving rather useful as I'd like to learn how not to kill myself

[Weekend_Climberz]

In the two falls I've caught on ice, one ice screw placement was with a screamer and one placement was without. Both placements were in good ice (though I would go as far to say the ice was indeed better on the placement with the screamer). The screw that did not have a screamer on it blew a bit of ice around the screw, but held firmly (~30 foot whipper). The one that did have a screamer, didn't show any signs whatsoever of any ice being displaced from the impact (~20 foot whipper). Take from that what you will.

[selkirk]

What were the fall factors like?

[Weekend_Climberz]

Pretty low I would imagine. Less than factor 1 for sure and with half ropes in both cases which will significantly reduce the impact forces compared with a single rope.

[nordicpunk]

I voted for "screamer every time" for 5+ yrs. experience. I know from experience that they probably aren't always neccisary BUT- screamers are not that expensive and so I figure "why not?" probably 90+% of my placements get screamers. Also- very key is weekend climberz mention of the doubles. I did an impact study with Beal ropes here at MontanaState U. (grad student in movement science) and Double ropes have ~half the impact force of a 10.2 single line!

[TrogdortheBurninator]

I voted for "screamer every time" for 5+ yrs. experience. I know from experience that they probably aren't always neccisary BUT- screamers are not that expensive and so I figure "why not?" probably 90+% of my placements get screamers. Also- very key is weekend climberz mention of the doubles. I did an impact study with Beal ropes here at MontanaState U. (grad student in movement science) and Double ropes have ~half the impact force of a 10.2 single line!

 

I thought that I read somewhere that the real life gains of impact force with 1/2 ropes are not super dramatic. I am guessing this is because the reduced impact force is also accompanied by reduced total system friction, therefor a higher percentage of the fall force comes on the top piece.

[tvashtarkatena]

This brings up an important side point. I've read some posters on other forums who claim that they clip both their half ropes into a single biner because their 'nervous about falling on such a thin line'. Don't do it. You double your fall factor and increase the chance of pro failure accordingly. If your half rope is not also rated as a twin, don't clip both into one biner.

[Weekend_Climberz]

This brings up an important side point. I've read some posters on other forums who claim that they clip both their half ropes into a single biner because their 'nervous about falling on such a thin line'. Don't do it. You double your fall factor and increase the chance of pro failure accordingly. If your half rope is not also rated as a twin, don't clip both into one biner.

 

I believe that you would want to do this also due to the fact that the half ropes tend to stretch different lengths and when clipped in a single piece together the friction between the two strands becomes an issue. I'm not sure how a twin would not be subject to the same frictional forces other than simply the diameter of the ropes being less, therefore making the surface area less and then less friction between strands. Brings up the question to how a rope rated for both half and twin usage could make such a force negligible other than assuming that it's a negligible force to begin with. Which then brings me full circle. WTF am I talking about??

[tvashtarkatena]

I'm confused.

 

Maybe we should make it simpler: don't fall.

 

Physician, heal thyself.

[Weekend_Climberz]

Maybe we should make it simpler: don't fall.

 

I like that option best :tup:

[G-spotter]

I caught one fall years ago at Moaning Tree Wall where my buddy suddenly dinnerplated both tools out. He fell about 20 feet with rope stretch, and about 50 feet of rope out, onto a 17cm screw with a screamer on it (one of the OnSight ones). Approximately 1/3 of the length of the Screamer stitching ripped. The screw was totally unaffected - no shattering of ice or bending of tube.

 

From that I concluded that they work good.

[Kraken]

I had a bulge rip out on me taking me for a 48 foot ride.

 

I had a 10cm screw with a screamer on it. The screamer totally opened up and saved me from hitting the deck. My belayer was pulled forward a little bit so that might have created a little dynamic assistance to it.

 

That was the only fall I've ever taken. My mindset though is that screamers CERTAINLY don't hurt the matter. I climb with a double rope system and almost extensively screamers.

 

Also, I can verify that, while not optimal all situations, spectres have their niche. Moss and veggies suck those things up. They can be really solid if placed correctly.

 

[rbw1966]

The fall I took in Canada was on a screw with a screamer. The screamer completely ripped out but the screw held.

[mwalker]

This brings up an important side point. I've read some posters on other forums who claim that they clip both their half ropes into a single biner because their 'nervous about falling on such a thin line'. Don't do it. You double your fall factor and increase the chance of pro failure accordingly. If your half rope is not also rated as a twin, don't clip both into one biner.

 

I've heard this before but how would clipping both (half) ropes into one piece of protection double the fall factor? do you mean it increases the impact force on that piece; maybe because the two ropes together are less stretchy than one strand by itself?

[genepires]

fall factor is a function of how far you fall and how far you above the last protection. Rope types don't figure into it. Impact forces are affected by rope use. I don't know if you would double the impact force by using a half rope as a twin, but definately would be higher than using the half ropes as designed.

[TrogdortheBurninator]

i think in practice, differences in amount of rope played out will effectively limit peak impact force to only one of the ropes.

[tvashtarkatena]

This brings up an important side point. I've read some posters on other forums who claim that they clip both their half ropes into a single biner because their 'nervous about falling on such a thin line'. Don't do it. You double your fall factor and increase the chance of pro failure accordingly. If your half rope is not also rated as a twin, don't clip both into one biner.

 

I've heard this before but how would clipping both (half) ropes into one piece of protection double the fall factor? do you mean it increases the impact force on that piece; maybe because the two ropes together are less stretchy than one strand by itself?

 

Yes. Similarly, fatter single ropes produce higher fall factors than skinnier single ropes. You don't fall as far with a fatter rope, but you strain your pro more. Fall factor a simplified way to express peak force on your pro. Ropes are essentially springs of varying stiffness, so rope type is an integral part of determining fall factors. Peak load in this type of system is determined by a) spring stiffness (i.e., type of rope), b) spring length (how much rope is paid out and therefore is available to stretch and absorb the load), and the load itself load (how far you free fall and how fat your ass is). Imagine climbing on a thick steel cable. Think that might increase your fall factor a bit?

Edited February 29, 2008 by tvashtarkatena

[Jens]

I like carrying about three or so on every ice lead. The only reason I don't use all screamers as they are heavier, bulkier, harder to clip, less, sleak and expensive. I've taken two lead falls on pure ice. The fall that had a shitty screw in only had a regular QD on it and it held. Screamers are definitely nice to have though.

[glassgowkiss]

the tests done by BD some time ago showed that strength of the screw depends on the angle of the placement and the quality of the ice. also turns out that 13 cm screw held the same as 17cm. one might argue that the energy absorption by the screamer is achieved by lengthening of the fall, hence not real energy absorption is happening.

[G-spotter]

Hey Bob have you ever used the "Figure of 1" hooks?

[glassgowkiss]

Hey Bob have you ever used the "Figure of 1" hooks?

what? what are you trying to say?

[tvashtarkatena]

the tests done by BD some time ago showed that strength of the screw depends on the angle of the placement and the quality of the ice. also turns out that 13 cm screw held the same as 17cm. one might argue that the energy absorption by the screamer is achieved by lengthening of the fall, hence not real energy absorption is happening.

 

I don't know about the last statement, but 13 and 17 cm screws having similar holding strengths makes sense, because its the threads that provide the holding power, and thread length for all screws except stubbies is the same. Along these same lines, using a longer screw to penetrate bad ice and 'get to the good ice' is not a good practice; the increased screw length creates a longer cantilever force on the threads (the bad ice has little compression strength to prevent this, so it's as if the end of the screw is cantilevered out into the air) and increases the chance that the screw will blow. It's far better to excavate down to the good ice and place a shorter screw in this instance.