cap n chris
Well-known member
HANG ON! I'm left handed but have always used a Stop normally. Am I doing something wrong or am I not really a left handed person? Tell me! Please help!!!
Geoff,
Apart from the added control, (and the ease of soft-locking) one advantage of a braking crab is that almost any movement of the right hand will cause added friction, whether around the caver's body, or around the crab itself. Someone abseiling without one could end up changing their friction either up *or* down if they lift their right hand, depending how much friction they exert on the rope running through their right hand, since lifting the rope can reduce the amount of top-cam which the rope runs around.
Someone using a braking crab largely fixes the rope-entry-angle to the Stop, making the friction in the Stop itself depend solely on the nature of the rope, and its tension (caused by both the rope weight and by any extra drag added by the user to the down-rope).
A braking crab also helps stabilise the Stop in an upright position to some extent - without one, tension on the rope below pulling on the top of the Stop can make it tilt more towards the right. I'm not sure if a more tilt-prone Stop might contribute somewhat to 'snatchy' behaviour - it might depend what kind of grip there was on the handle.
I'm just thinking out loud, possibly talking rubbish but *presumably*, as a Stop tilted rightwards, it would tend to reduce in friction as the contact area with the cams decreased?
If hand/body friction was being added in order to slow down, would a tiliting Stop work against the wishes of the caver to some extent?
I'll have to have a play this weekend if I get on any suitable ropes.
Apart from the added control, (and the ease of soft-locking) one advantage of a braking crab is that almost any movement of the right hand will cause added friction, whether around the caver's body, or around the crab itself. Someone abseiling without one could end up changing their friction either up *or* down if they lift their right hand, depending how much friction they exert on the rope running through their right hand, since lifting the rope can reduce the amount of top-cam which the rope runs around.
Someone using a braking crab largely fixes the rope-entry-angle to the Stop, making the friction in the Stop itself depend solely on the nature of the rope, and its tension (caused by both the rope weight and by any extra drag added by the user to the down-rope).
A braking crab also helps stabilise the Stop in an upright position to some extent - without one, tension on the rope below pulling on the top of the Stop can make it tilt more towards the right. I'm not sure if a more tilt-prone Stop might contribute somewhat to 'snatchy' behaviour - it might depend what kind of grip there was on the handle.
I'm just thinking out loud, possibly talking rubbish but *presumably*, as a Stop tilted rightwards, it would tend to reduce in friction as the contact area with the cams decreased?
If hand/body friction was being added in order to slow down, would a tiliting Stop work against the wishes of the caver to some extent?
I'll have to have a play this weekend if I get on any suitable ropes.
Peter Burgess
New member
I would feel very uncomfortable braking with my right hand. I use my Stop the 'left-handed' way. I have never found a problem with the STOP handle and the croll getting in the way of each other.
BTW, I use my knife and fork right-handed. I use my computer mouse with my left hand but I haven't reconfigured the left/right click buttons. Handedness comes in degrees and is not an absolute. Apart from the threading issue you raised, I find the STOP not to be a strongly-handed device.
I go 50-50 with the advantages etc of racks and stops. I have no preference apart from the stop being easier to carry around than my rack.
BTW, I use my knife and fork right-handed. I use my computer mouse with my left hand but I haven't reconfigured the left/right click buttons. Handedness comes in degrees and is not an absolute. Apart from the threading issue you raised, I find the STOP not to be a strongly-handed device.
I go 50-50 with the advantages etc of racks and stops. I have no preference apart from the stop being easier to carry around than my rack.
pisshead
New member
i've already said i'm a rack user, so correct me if i'm wrong, but I understood you should never use the brake to control your speed as this wore out the brake and therefore ruined the whole point of a stop - that you could rely on the brake in an emergency.
I thought the brake should be held fully off for the entire descent.
Quite a few people have mentioned having it partially on - this is wrong, yes?
I thought the brake should be held fully off for the entire descent.
Quite a few people have mentioned having it partially on - this is wrong, yes?
A
andymorgan
Guest
Mr Wallop, in Mendip you would rarely use a descender anyway!
A ladder is more of a challenge to descend! (but more expensive)
A ladder is more of a challenge to descend! (but more expensive)
paul
Moderator
pisshead said:
According to Petzl's instructions, it is wrong: see http://en.petzl.com/ProduitsServices/D09 STOP D09800-H.pdf
"...Braking and descent control are effected by varying the grip of the hand on the free end of the rope. Release the handle handle to activate the self-braking function, Squeeze the handle to deactivate the self-braking function and allow the rope to run."
I'd only maybe partially-release in the case of occasional drops on very thin +/or slippy rope, which would possibly be slipping through the brake anyway, making it more a case of making a slipping brake slip a bit more. The big downside to doing that is that if you push the handle in further, you would go faster or have to grip harder or otherwise change the right hand-position.
However, with a very thin rope, (or a fairly thin rope on a Stop with a worn top-cam, it's likely that the handle wouldn't have to move very far for the brake to be fully released - there's at least some argument for (at least initially) only *just* carefully and fully releasing the lock on thin ropes of uncertain friction, to make it easier to rapdily release and for the brake to reapply if descent gets a bit fast, or even for switching to a grip that allows the handle to be pulled out as well as pushed in, if you're really uncertain what might happen.
However, with a very thin rope, (or a fairly thin rope on a Stop with a worn top-cam, it's likely that the handle wouldn't have to move very far for the brake to be fully released - there's at least some argument for (at least initially) only *just* carefully and fully releasing the lock on thin ropes of uncertain friction, to make it easier to rapdily release and for the brake to reapply if descent gets a bit fast, or even for switching to a grip that allows the handle to be pulled out as well as pushed in, if you're really uncertain what might happen.
Brains
Well-known member
500' of brand new off the reel 10mm rope in a bag clipped to my harness & Mandale Founder Shaft and a worn stop = petzl zoom.
No rope weight below me (in the bag) and handle not only released but pulled out as well, a brake krab and looped over the top spigot of the stop was definetly still going a bit quick, even with the two organic 5 bar racks fully applied. Sizzled a bit in the flooded shaft at the bottom, but at least I didnt stop anywhere to damage the rope!! VERY SCARY
No rope weight below me (in the bag) and handle not only released but pulled out as well, a brake krab and looped over the top spigot of the stop was definetly still going a bit quick, even with the two organic 5 bar racks fully applied. Sizzled a bit in the flooded shaft at the bottom, but at least I didnt stop anywhere to damage the rope!! VERY SCARY
Brand-new, off-the reel?
*coughs*
Repeatedly soaking and draining a new rope before first use until all the detergent is removed (the water and rope no longer feel or taste soapy) does tend to make rope much nicer to descend, and also helps to settle the sheath onto the core, reducing the chance of kinking.
It also helps to shrink the rope to closer to its ultimate length.
*coughs*
Repeatedly soaking and draining a new rope before first use until all the detergent is removed (the water and rope no longer feel or taste soapy) does tend to make rope much nicer to descend, and also helps to settle the sheath onto the core, reducing the chance of kinking.
It also helps to shrink the rope to closer to its ultimate length.
Potholer, thanks, I agree.
Ive no plan to change from always using a braking crab, glove and stop/go action with the handle. It works fine for me and how I was originally taught, but Im always looking out for suggestions. The only mod I certainly like is using some form of dedicated braking crab, in my case a Raumer <handy>, where its approrpiate.
Enjoy your weekend rope trials
D
Dep
Guest
I have tried a rack - nice and smooth but faffy to rig (my inexperience!) and I would hate to do anything other than a simple free-hanging pitch with it.
Right from the off the plummet was explained to me and its potential for a nasty accident. At a later date I also watched the Cave Safe videos and saw Andy Sparrow's demonstration of a plummeting accident. I thought the whole video section on the stop and plummeting in particular was clear and simple for anyone of normal intelligence who believes in Darwinian evolution.
I'm right-handed and use a stop with a braking krab. For me these have two distinct functions and there is a very close analogy to the way in which the clutch and throttle pedals are used in a car when pulling away and stopping.
Initially I have the car in gear --- locks off, hands on, ready to descend
Give the engine some revs ---- relax the rope in my right hand slightly against the krab so I could move a little..
Start to bring the clutch up ---- squeeze the handle in -
Feel for the biting point ---- Feel for the biting point
Increase revs ---- bring right-hand down to ease off the braking krab
Feed the clutch all the way out whilst increasing revs --- squeeze handle right in, bring right hand down to release brake
Until the clutch is fully up ---- lever right in
All control is now on the throttle ----- right-hand + braking krab...
Stopping and moving slowly in a controlled fashion is much the same idea.
My general attitude to safety is common sense - yes I could hurt myself with a stop so I pay attention to what I am doing in direct proportion to how much it is going to hurt/cripple/kill me if I don't!
The knocked unconscious argument also holds for me - only the stop gives you any sort of chance at all (yes I know you will likely end up at the bottom anyway but maybe a little slower!)
I can't be arsed to mention the statistics, it's been done already in this thread - the numbers are clear but the causality is not.
Stops vs bobbins - apples vs pears
I do agree with Andy Sparrow's general point about raising the profile of this issue - to let someone use one without warning them of this nasty potential would be criminally negligent.
I do not think that any experienced caver is unaware of the issues with Stops, and as long as everyone realises that they have a duty to make sure all novices are fully aware of this issue then I don't think it is a big deal, the stop is a versatile piece of kit, and no one should use any equipment until they (and those with them!!!) are 100% sure that they understand its use - training!
There is perhaps some merit in getting people to have a go at regular abseiling with a Fig-8 to understand the 'let-go-and-you-die' principle before trying a stop.
I also think that Petzl's matchstick man diagrams are woefully inadequate.
Would efforts not be better directed at Petzl to include a proper piece of literature which specifically explains clutch and plummet with proper pictures and explanatory text.
One other point that should also perhaps be made to beginners and anyone seen with their right hand not on the rope...
The slow creep of a stop lulls you into a false sense of security - "if I slip I will easily be able to grab the rope with my right hand before it gets out of control" - yeah right!
It only takes about half a second for the rope to accelerate to a palm burning speed, and then you won't be able to hold it or will run your fingers into the braking krab.
I prefer to cave/SRT with bare hands as I like to feel what I am doing - but am slowly coming round to the idea of climber's gloves to protect my palms.
But at the end of the day I am sure the real danger lies in dangling over a long drop on a piece of rope, misusing the stop is just one of a multitude of hazards.
Right from the off the plummet was explained to me and its potential for a nasty accident. At a later date I also watched the Cave Safe videos and saw Andy Sparrow's demonstration of a plummeting accident. I thought the whole video section on the stop and plummeting in particular was clear and simple for anyone of normal intelligence who believes in Darwinian evolution.
I'm right-handed and use a stop with a braking krab. For me these have two distinct functions and there is a very close analogy to the way in which the clutch and throttle pedals are used in a car when pulling away and stopping.
Initially I have the car in gear --- locks off, hands on, ready to descend
Give the engine some revs ---- relax the rope in my right hand slightly against the krab so I could move a little..
Start to bring the clutch up ---- squeeze the handle in -
Feel for the biting point ---- Feel for the biting point
Increase revs ---- bring right-hand down to ease off the braking krab
Feed the clutch all the way out whilst increasing revs --- squeeze handle right in, bring right hand down to release brake
Until the clutch is fully up ---- lever right in
All control is now on the throttle ----- right-hand + braking krab...
Stopping and moving slowly in a controlled fashion is much the same idea.
My general attitude to safety is common sense - yes I could hurt myself with a stop so I pay attention to what I am doing in direct proportion to how much it is going to hurt/cripple/kill me if I don't!
The knocked unconscious argument also holds for me - only the stop gives you any sort of chance at all (yes I know you will likely end up at the bottom anyway but maybe a little slower!)
I can't be arsed to mention the statistics, it's been done already in this thread - the numbers are clear but the causality is not.
Stops vs bobbins - apples vs pears
I do agree with Andy Sparrow's general point about raising the profile of this issue - to let someone use one without warning them of this nasty potential would be criminally negligent.
I do not think that any experienced caver is unaware of the issues with Stops, and as long as everyone realises that they have a duty to make sure all novices are fully aware of this issue then I don't think it is a big deal, the stop is a versatile piece of kit, and no one should use any equipment until they (and those with them!!!) are 100% sure that they understand its use - training!
There is perhaps some merit in getting people to have a go at regular abseiling with a Fig-8 to understand the 'let-go-and-you-die' principle before trying a stop.
I also think that Petzl's matchstick man diagrams are woefully inadequate.
Would efforts not be better directed at Petzl to include a proper piece of literature which specifically explains clutch and plummet with proper pictures and explanatory text.
One other point that should also perhaps be made to beginners and anyone seen with their right hand not on the rope...
The slow creep of a stop lulls you into a false sense of security - "if I slip I will easily be able to grab the rope with my right hand before it gets out of control" - yeah right!
It only takes about half a second for the rope to accelerate to a palm burning speed, and then you won't be able to hold it or will run your fingers into the braking krab.
I prefer to cave/SRT with bare hands as I like to feel what I am doing - but am slowly coming round to the idea of climber's gloves to protect my palms.
But at the end of the day I am sure the real danger lies in dangling over a long drop on a piece of rope, misusing the stop is just one of a multitude of hazards.
DEP wrote
http://www.caves.org.au/s_cave_safety.htm#eight
but ive never seen a UK National equivalent that <new> SRTers could be given as consistant advice and as an expection check list for Clubs to use as a measure of initial safe training. Does this exist ??
considering other <risk> sports such as Scuba Diving and Hang Gliding, tests and log books and certificates, it seems we cavers are currently lucky to have a relatively relaxed and informal situation here ......
I see that the Australian Speleological Federation spells out in simple terms what it expects of SRT's skills ......
http://www.caves.org.au/s_cave_safety.htm#eight
but ive never seen a UK National equivalent that <new> SRTers could be given as consistant advice and as an expection check list for Clubs to use as a measure of initial safe training. Does this exist ??
considering other <risk> sports such as Scuba Diving and Hang Gliding, tests and log books and certificates, it seems we cavers are currently lucky to have a relatively relaxed and informal situation here ......
cap n chris
Well-known member
STEADY! WALK AWAY FROM THIS TOPIC, THERE'S NOTHING TO SEE HERE! :shock:
M
MSD
Guest
Probably true Chris.....
I use a Stop alomst exclusively. For me it gives a smooth ride, it's fast to take on and off and I like the stop function, mainly because it saves time at pitchheads and rebelays since you can skip locking off provided that you have a cowstail in. It is also handier and lighter than a rack, which I would never use uless I was going to Golondrinas or similar.
I have trained dozens and dozens of people to abseil and 95% of them have used a Stop. Only one person (to my knowledge) has hurt themselves and that was due to loading the descender with a C-rig to descend a very stiff rope. Unfortunately she got less friction than she bargained for. That accident would have happened with a Simple too and maybe with a rack (if you set off with too few bars in).
Based on my experience I am pretty sceptical of Andy Sparrow's opinion. Most people I have trained have got a Stop cracked in about 30 minutes, including an "emergency stop" drill. Let's be honest, it's not rocket science. It's easy to see holes in the statistical arguments too. For example the 25% of French cavers who use a Stop have more accidents than the 75% that use a Simple. But since the French training system adopts the Simple, the Simple users are quite possibly better trained. Controlling for all these sorts of external factors is very, very difficult in a statistical analysis where the number of incidents is vanishingly small compared to the total population.
It seems to me that NO abseiling device is fail safe. With a rack or Simple you will fall if you let go with your right hand. With a Stop you can fall if you "panic grip" the handle and don't have proper control of the rope with the right hand. You can even fall with a I'D if you really try hard enough.
For an abseiling device to be fail safe it would have to have a maximum speed limtation, i.e. no matter what you do with the device itself or the rope you would not be able to go faster than say, 1 metre per second. (I have plucked this number from thin air, I don't know how realistic it is).
Mark
P.S the guy lifelining with a shunt was not, it seems, very competent. Athough it was not a good idea to use a shunt in the first place, he compounded this mistake by not understanding what happens when you release a shunt under load (it releases totally). What he should have done is belayed the rope with a friction hitch before releasing the shunt.
I use a Stop alomst exclusively. For me it gives a smooth ride, it's fast to take on and off and I like the stop function, mainly because it saves time at pitchheads and rebelays since you can skip locking off provided that you have a cowstail in. It is also handier and lighter than a rack, which I would never use uless I was going to Golondrinas or similar.
I have trained dozens and dozens of people to abseil and 95% of them have used a Stop. Only one person (to my knowledge) has hurt themselves and that was due to loading the descender with a C-rig to descend a very stiff rope. Unfortunately she got less friction than she bargained for. That accident would have happened with a Simple too and maybe with a rack (if you set off with too few bars in).
Based on my experience I am pretty sceptical of Andy Sparrow's opinion. Most people I have trained have got a Stop cracked in about 30 minutes, including an "emergency stop" drill. Let's be honest, it's not rocket science. It's easy to see holes in the statistical arguments too. For example the 25% of French cavers who use a Stop have more accidents than the 75% that use a Simple. But since the French training system adopts the Simple, the Simple users are quite possibly better trained. Controlling for all these sorts of external factors is very, very difficult in a statistical analysis where the number of incidents is vanishingly small compared to the total population.
It seems to me that NO abseiling device is fail safe. With a rack or Simple you will fall if you let go with your right hand. With a Stop you can fall if you "panic grip" the handle and don't have proper control of the rope with the right hand. You can even fall with a I'D if you really try hard enough.
For an abseiling device to be fail safe it would have to have a maximum speed limtation, i.e. no matter what you do with the device itself or the rope you would not be able to go faster than say, 1 metre per second. (I have plucked this number from thin air, I don't know how realistic it is).
Mark
P.S the guy lifelining with a shunt was not, it seems, very competent. Athough it was not a good idea to use a shunt in the first place, he compounded this mistake by not understanding what happens when you release a shunt under load (it releases totally). What he should have done is belayed the rope with a friction hitch before releasing the shunt.
cap n chris
Well-known member
MSD said:
Wallop and Andy are both known to me; Andy's original interjection was to point out that in response to Wallop's query about what was the best descending device to get for his first SRT kit, there was no mention made of the Petzl Stop's record of implication in avoidable accidents from poor training - this, I feel, is a fair comment. i.e. Whenever a Stop is mentioned to a newbie the need for PROPER TRAINING should also be pointed out.
Am I misunderstanding this and/or out of order? :wink:
paul
Moderator
MSD said:
Totally agree. And with non-autolock desceders, the user is very aware of the danger of letting go with the controlling hand. However, I feel many inexperienced Stop users have not been properly trained to use the controlling hand to control the rate of descent as with most other descenders and have too much emphasis put on the "let go of the handle in case of emergency". Of course the involuntary releasing of the handle in case of unconciousness, leading to a slow down of descent is obviously beneficial and is a useful safety feature.
But I wonder how realistically would the out of control caver be able to release the handle in a panic. Its all very well under ideal conditions while training, to begin sliding down the rope and say "right, let go of the handle" and happily come to a safe stop on the rope. In a real situation, in a panic, I would have said that involunatrily grabbing anything and everything takes over and over-reliance on letting go of the handle as opposed to maintaining a firm grip on the controlling rope leads to the "clutch and plummet".
Paul wrote :
The difference between a Simple and the Stop is obviously the brake capability that is a most useful feature in normal caving. As we know the two possible ways of using this brake is either 1) as a stop/go <handbrake> type lever or as 2) a variable speed control <foot brake> type lever.
Use the lever as a variable foot brake and your SECOND variable foot brake is your right hand rope control. This asks the brain to coordinate two separate variable devices in combination to achieve effect, one to <vary towards clenching tight to stop> and at the same time the other to <vary towards letting go completely to stop> and this <twin> variable control generally works well as a lot of cavers know.
Now panic occurs and the left hand clutches the lever in - lets assume this is an inevitable reflex with most people - you have now in effect only turned the Stop into a Simple, nothing more ! The brain of course attempts to control speed with the right hand, but because less attention has been placed on this SOLE aspect of speed control, I surmise the user is not so well prepared. Perhaps no glove, perhaps no braking crab, perhaps no feeling of just how much effort needs to be expended <quickly> before exponentially energy gets out of control .....
In the Alternate case, if the lever was ALWAYS used just as a stop/go handbrake, more training and user emphasis is automatically directed to ALWAYS controlling speed with the right hand and doing it as the ONLY method of speed control, the Stop effectively becomes a <Simple> in all normal use, until such occasions as its additional brake capability is really required, for normal SRT procedures (handbrake on) OR due to a rock fall !
Logic suggests that there must be a better chance that the person trained to use the Stops brake capability ONLY as an ON / OFF handbrake, ( i.e. as a Simple in normal descent use) has better chances to avoid, or recover from, any dangerous high speed.
Andy Sparrow concludes, as I understand, that the Simple is the safest - in fundamental terms I believe he is today absolutely right, BUT my supposition would be that this is SOLELY because, (in addition to the danger of clutch and plummet) Stop users are not today being made fully aware and trained that a) they should NOT use the lever as a variable friction brake, but rely totally on their right hand to brake and b) they must be made aware that the Stops basic engineering design will encourage its use as a variable friction brake as this requires less user effort on the lever, BUT that this MUST be avoided at all costs and not forgotten. It seems to me that by ensuring these points, the Stop can be as safe as the Simple AND give the caver additional advantages ...... and indeed it has the potential to prove statistically, in time, that it is actually safer than a Simple, if used in the above manner.
Now while I can claim to evaluate the Stop as an Engineer, I'm relatively new to SRT compared to some of you guys ..... have I got the wrong end of the stick ?? (Im not talking about what we may sucessfully do in practice but what we should do to limit risk)
Of Stop users that have had accidents, are there any statistics as to their normal braking technique of a) stop/go or b) variable use of the handle ??
There seems potential arguement that training should not place any emphasis on letting go of the lever to stop - an event that is unlikely to occur in an emergency, unless exceptional regular training has taken place ? Indeed thinking along the lines of different training methods ....
The difference between a Simple and the Stop is obviously the brake capability that is a most useful feature in normal caving. As we know the two possible ways of using this brake is either 1) as a stop/go <handbrake> type lever or as 2) a variable speed control <foot brake> type lever.
Use the lever as a variable foot brake and your SECOND variable foot brake is your right hand rope control. This asks the brain to coordinate two separate variable devices in combination to achieve effect, one to <vary towards clenching tight to stop> and at the same time the other to <vary towards letting go completely to stop> and this <twin> variable control generally works well as a lot of cavers know.
Now panic occurs and the left hand clutches the lever in - lets assume this is an inevitable reflex with most people - you have now in effect only turned the Stop into a Simple, nothing more ! The brain of course attempts to control speed with the right hand, but because less attention has been placed on this SOLE aspect of speed control, I surmise the user is not so well prepared. Perhaps no glove, perhaps no braking crab, perhaps no feeling of just how much effort needs to be expended <quickly> before exponentially energy gets out of control .....
In the Alternate case, if the lever was ALWAYS used just as a stop/go handbrake, more training and user emphasis is automatically directed to ALWAYS controlling speed with the right hand and doing it as the ONLY method of speed control, the Stop effectively becomes a <Simple> in all normal use, until such occasions as its additional brake capability is really required, for normal SRT procedures (handbrake on) OR due to a rock fall !
Logic suggests that there must be a better chance that the person trained to use the Stops brake capability ONLY as an ON / OFF handbrake, ( i.e. as a Simple in normal descent use) has better chances to avoid, or recover from, any dangerous high speed.
Andy Sparrow concludes, as I understand, that the Simple is the safest - in fundamental terms I believe he is today absolutely right, BUT my supposition would be that this is SOLELY because, (in addition to the danger of clutch and plummet) Stop users are not today being made fully aware and trained that a) they should NOT use the lever as a variable friction brake, but rely totally on their right hand to brake and b) they must be made aware that the Stops basic engineering design will encourage its use as a variable friction brake as this requires less user effort on the lever, BUT that this MUST be avoided at all costs and not forgotten. It seems to me that by ensuring these points, the Stop can be as safe as the Simple AND give the caver additional advantages ...... and indeed it has the potential to prove statistically, in time, that it is actually safer than a Simple, if used in the above manner.
Now while I can claim to evaluate the Stop as an Engineer, I'm relatively new to SRT compared to some of you guys ..... have I got the wrong end of the stick ?? (Im not talking about what we may sucessfully do in practice but what we should do to limit risk)
Of Stop users that have had accidents, are there any statistics as to their normal braking technique of a) stop/go or b) variable use of the handle ??
