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Bolt hole patch opinion

Discussion in 'Archives - Yahoo Canyons Group' started by Luke, Dec 1, 2012.

  1. Luke

    Luke Guest

    As you may have heard we have a bolt fairy installing a ton of bolts in Red Rock. Rumor on the street is our bolt fairy has moved to Death Valley and may have stricken a couple routes there. The problem is, all the bolts (both in Death Valley and in Red Rock) are in places where it is illegal to bolt.



    Death Valley has recently began exploring a permit system. Having bolts pop up on routes could easily encouraged policy makers to decisions NOT in favor of the canyoneering community. I feel the canyon community as a whole should be capable of policing itself to some degree. A group of us will be going into a couple routes in Death Valley to look for and possibly remove the illegal bolts.



    I have a specific question related to safety with respect to patching holes left from bolt removal.



    When a bolt is in a wall and is pulled on, the stress created in the rock is roughly a cone where the point is at the tip of the bolt (down in the rock) and the extends outward at about a 45 degree angle toward the surface of the rock. So a 3 inch bolt would have a stress zone around the bolt at the surface of the rock of about a 6 inch diameter (3 inch radius circle with the hanger in the center of that zone). This is one reason to space bolts apart when installing them. It is a good idea to not have those cones of stress overlap.



    If a bolt is removed and patched, there can be a weak spot left in the rock (the hole). It is possible that some patching methods could make the hole stronger than the original rock. But I tend to think the hole will be weaker as a result of the process. Not all patch jobs will be the same or there may be part of the bolt left in the wall, etc. If the bolt left in the wall does happen to get oxygen, it can rust and expand, putting force on the patch over time weakening it further.



    If a new bolt is installed next to the old patched bolt hole, then the new cone of stress overlaps into the area where the old hole is. Assuming the patched area is weaker this would not be a good thing. I assume someone placing bolts would know about this stuff and avoid placing bolts near old holes or obvious weak imperfections in the rock.



    But what would happen if the patch were done so well that it was practically invisible, even when inspected? If someone came back to install bolts and chose the same location, they could place the bolt in a weak section of rock and not know it. So if one could patch a bolt hole and make it invisible is that a safe thing to do? Would it be safer to make the patch blend well for aesthetic sense but leave it at least a little obvious for safety reasons?



    As odd as it sounds, I am wondering if a completely invisible patch is safe in the event another bolt is placed next to it then used?



    I am curious about the opinions of the safety aspect of an invisible patch. I am NOT interested in a bolt war conversation.

    This is not a post to get the bolt war topic restarted. I would like to encourage people to keep this from taking the bolt war argument path.

    If you do have any thoughts on what was actually asked I would love to hear them.



    It is valuable to have a forum like this where so many voices and minds can reach out and touch one another. Luke





  2. RAM

    RAM Guest

    More later, but right off the top...a few bolts showed up, in the last year or so, in some of the lesser canyons in Death Valley and the park service is PISSED! All this happening when the management plan that will guide policy for 20 years is being decided upon.....and some form of permit system will be installed soon. I think we must contact the park and offer our services and support. Show that there is a community that cares about the rules and will support the park. I know that American Canyoneers http://www.americancanyoneers.org/ was looking to be involved and has some feelers out. Sounds like acting sooner rather than later is key. I have some potential contacts. Any one else have some suggested approaches? Thanks for the wake up call, Luke. Many of you, if not most of you may not have been to DV for canyoneering yet. Trust me! Its is a place worthy of our efforts to keep access open.

    Please document your efforts if you go pro-active. I am almost certain that the park will support the effort, so contacting them might be the best avenue. Contact me at adkramoo at aol dot com for contact information.

    BTW this is not a bolt vs. non bolt issue. Bolts are illegal, DV is also the easiest natural anchor environment I have ever seen or could imagine. Sigh! ram

    --- In Yahoo Canyons Group, "Luke" <luke@...> wrote:
    As you may have heard we have a bolt fairy installing a ton of bolts in Red > Rock. Rumor on the street is our bolt fairy has moved to Death Valley and > may have stricken a couple routes there. The problem is, all the bolts > (both in Death Valley and in Red Rock) are in places where it is illegal to > bolt.

    Death Valley has recently began exploring a permit system. Having bolts pop > up on routes could easily encouraged policy makers to decisions NOT in favor > of the canyoneering community. I feel the canyon community as a whole > should be capable of policing itself to some degree. A group of us will be > going into a couple routes in Death Valley to look for and possibly remove > the illegal bolts.

    I have a specific question related to safety with respect to patching holes > left from bolt removal.

    When a bolt is in a wall and is pulled on, the stress created in the rock is > roughly a cone where the point is at the tip of the bolt (down in the rock) > and the extends outward at about a 45 degree angle toward the surface of the > rock. So a 3 inch bolt would have a stress zone around the bolt at the > surface of the rock of about a 6 inch diameter (3 inch radius circle with > the hanger in the center of that zone). This is one reason to space bolts > apart when installing them. It is a good idea to not have those cones of > stress overlap.

    If a bolt is removed and patched, there can be a weak spot left in the rock > (the hole). It is possible that some patching methods could make the hole > stronger than the original rock. But I tend to think the hole will be > weaker as a result of the process. Not all patch jobs will be the same or > there may be part of the bolt left in the wall, etc. If the bolt left in > the wall does happen to get oxygen, it can rust and expand, putting force on > the patch over time weakening it further.

    If a new bolt is installed next to the old patched bolt hole, then the new > cone of stress overlaps into the area where the old hole is. Assuming the > patched area is weaker this would not be a good thing. I assume someone > placing bolts would know about this stuff and avoid placing bolts near old > holes or obvious weak imperfections in the rock.

    But what would happen if the patch were done so well that it was practically > invisible, even when inspected? If someone came back to install bolts and > chose the same location, they could place the bolt in a weak section of rock > and not know it. So if one could patch a bolt hole and make it invisible is > that a safe thing to do? Would it be safer to make the patch blend well for > aesthetic sense but leave it at least a little obvious for safety reasons?

    As odd as it sounds, I am wondering if a completely invisible patch is safe > in the event another bolt is placed next to it then used?

    I am curious about the opinions of the safety aspect of an invisible patch. > I am NOT interested in a bolt war conversation.
    This is not a post to get the bolt war topic restarted. I would like to > encourage people to keep this from taking the bolt war argument path.
    If you do have any thoughts on what was actually asked I would love to hear > them.

    It is valuable to have a forum like this where so many voices and minds can > reach out and touch one another. > Luke


    >
  3. TomJones

    TomJones Guest

    --- In Yahoo Canyons Group, "Luke" <luke@...> wrote:
    As you may have heard we have a bolt fairy installing a ton of bolts in Red Rock. Rumor on the street is our bolt fairy has moved to Death Valley and may have stricken a couple routes there. The problem is, all the bolts (both in Death Valley and in Red Rock) are in places where it is illegal to bolt. > Ugh! Double Ugh!

    > ... > So if one could patch a bolt hole and make it invisible is > that a safe thing to do? Would it be safer to make the patch blend well for aesthetic sense but leave it at least a little obvious for safety reasons? >

    Interesting theoretical question, though in practice it is an easy question to answer. (no problemo!)

    The "cone of sheer" analysis determines the theoretical limit of strength of the medium into which the bolt is set, assuming a homogeneous solid. It is a useful model, but it applies poorly to what we actually do, because mechanical bolts rarely if ever fail this way in the field. The sheer strength of the rock, even Navajo sandstone, is rarely the weak link in the chain.

    It is possible to achieve the kind of bolt-rock bond that would allow for a cone-of-sheer failure by using short, big glue-in bolts, well-installed.

    In the field, I see several problems with applying this issue:

    1. Patching holes well is difficult. Patching holes so that upon close examination they are un-noticeable is virtually impossible. Drilling a hole within a few inches of a patch and not noticing seems very unlikely - then again, thinking you need bolts in RR and DV is also unlikely.

    2. In order to compromise the strength of the new bolt, the new hole would probably have to intersect the old one, or be very, very close to it. Seems like the driller would notice either while drilling, or while setting the bolt.

    3. The forces we apply to the bolt while rappelling (about 500 lbs max) are considerably below the general strength of the bolts (5000 lbs) or of the sheer cone (10,000 lbs). Even very close to an old hole, it is unlikely to result in failure.

    While I appreciate your concern over this issue, may I suggest that this is one thing you can not be concerned about.

    Tom Jones MIT II-'82 BS Mechanical Engineering
  4. Luke

    Luke Guest

    Thanks for the info Tom;



    So if I am getting this right the patched hole could weaken the stress cone if stressed to the full strength sheer cone area. But when canyoneering we do not even come close to this rating so we never stress the system to the point where this would be an issue.



    I did a quick (very quick not extensive) look at some ratings and the sheer strength of the bolts seems to range from 4500 pounds to 8000 pounds depending on bolt size, bolt material and what spec sheet you look at. I did not look into the sheer cone and took your word for it that the sheer cone itself is much stronger than the bolt itself (close to double).



    While rappelling under normal circumstances we may put up to 500 pounds on the bolt which is small percentage of the forces required to stress the bolt. And the sheer cone is much stronger than the bolt.



    Now if someone were to take a major fall on the system, a considerably larger force could be generated. Carabiners, rope, slings, rapids, etc all seem to have ratings in the same range or even lower than the sheer force ratings for bolts. So if a fall were taken, the bolts are one of many possible week links in the system (where all are close to the same rating anyway).



    The sheer cone would still be stronger than the bolt itself under sheer loads? Is that correct? So the sheer cone would still be much stronger than the sheer force of the bolt even if there were a patched hole within the sheer cone?



    After looking at it that way I see that a weakened sheer cone is still stronger than any part of the system anyway. Unless of course as you say the new bolt is drilled into or next to the patched hole.



    Thanks

    Luke



    P.S. - 1 Yup needing bolts in DV is a little hard to imagine. But there could be a nemesis out there.

    P.S. - 2 Nice credentials added to the signature



    From: Yahoo Canyons Group [mailto:Yahoo Canyons Group] On Behalf Of TomJones Sent: Sunday, December 02, 2012 9:36 AM To: Yahoo Canyons Group Subject: [from Canyons Group] Re: Bolt hole patch opinion





    --- In Yahoo Canyons Group <mailto:canyons%40yahoogroups.com> , "Luke" <luke@...> wrote:
    As you may have heard we have a bolt fairy installing a ton of bolts in Red Rock. Rumor on the street is our bolt fairy has moved to Death Valley and may have stricken a couple routes there. The problem is, all the bolts (both in Death Valley and in Red Rock) are in places where it is illegal to bolt. > Ugh! Double Ugh!

    > ... > So if one could patch a bolt hole and make it invisible is > that a safe thing to do? Would it be safer to make the patch blend well for aesthetic sense but leave it at least a little obvious for safety reasons? >

    Interesting theoretical question, though in practice it is an easy question to answer. (no problemo!)

    The "cone of sheer" analysis determines the theoretical limit of strength of the medium into which the bolt is set, assuming a homogeneous solid. It is a useful model, but it applies poorly to what we actually do, because mechanical bolts rarely if ever fail this way in the field. The sheer strength of the rock, even Navajo sandstone, is rarely the weak link in the chain.

    It is possible to achieve the kind of bolt-rock bond that would allow for a cone-of-sheer failure by using short, big glue-in bolts, well-installed.

    In the field, I see several problems with applying this issue:

    1. Patching holes well is difficult. Patching holes so that upon close examination they are un-noticeable is virtually impossible. Drilling a hole within a few inches of a patch and not noticing seems very unlikely - then again, thinking you need bolts in RR and DV is also unlikely.

    2. In order to compromise the strength of the new bolt, the new hole would probably have to intersect the old one, or be very, very close to it. Seems like the driller would notice either while drilling, or while setting the bolt.

    3. The forces we apply to the bolt while rappelling (about 500 lbs max) are considerably below the general strength of the bolts (5000 lbs) or of the sheer cone (10,000 lbs). Even very close to an old hole, it is unlikely to result in failure.

    While I appreciate your concern over this issue, may I suggest that this is one thing you can not be concerned about.

    Tom Jones MIT II-'82 BS Mechanical Engineering
  5. Neil

    Neil Guest

    Luke,

    I think the answer to your question about the cosmetics of a patch are situation specific. Isn't most of life?

    The answer to your question, in my mind, would vary if you were 'moving' a fixed station in a 'trade route' vs. pulling some bolts in some obscure locality infrequently traveled.

    Personally, if I was pulling and patching I would just do the best job I could and let Karma take care of the rest without over thinking it.

    Just 1 man's opinion, Neil

    Regardless, I think Tom's response is applicable.

    --- In Yahoo Canyons Group, "Luke" <luke@...> wrote:
    Thanks for the info Tom;

    So if I am getting this right the patched hole could weaken the stress cone > if stressed to the full strength sheer cone area. But when canyoneering we > do not even come close to this rating so we never stress the system to the > point where this would be an issue.

    I did a quick (very quick not extensive) look at some ratings and the sheer > strength of the bolts seems to range from 4500 pounds to 8000 pounds > depending on bolt size, bolt material and what spec sheet you look at. I > did not look into the sheer cone and took your word for it that the sheer > cone itself is much stronger than the bolt itself (close to double).

    While rappelling under normal circumstances we may put up to 500 pounds on > the bolt which is small percentage of the forces required to stress the > bolt. And the sheer cone is much stronger than the bolt.

    Now if someone were to take a major fall on the system, a considerably > larger force could be generated. Carabiners, rope, slings, rapids, etc all > seem to have ratings in the same range or even lower than the sheer force > ratings for bolts. So if a fall were taken, the bolts are one of many > possible week links in the system (where all are close to the same rating > anyway).

    The sheer cone would still be stronger than the bolt itself under sheer > loads? Is that correct? So the sheer cone would still be much stronger > than the sheer force of the bolt even if there were a patched hole within > the sheer cone?

    After looking at it that way I see that a weakened sheer cone is still > stronger than any part of the system anyway. Unless of course as you say > the new bolt is drilled into or next to the patched hole.

    Thanks
    Luke

    P.S. - 1 Yup needing bolts in DV is a little hard to imagine. But there > could be a nemesis out there.
    P.S. - 2 Nice credentials added to the signature

    From: Yahoo Canyons Group [mailto:Yahoo Canyons Group] On Behalf Of > TomJones > Sent: Sunday, December 02, 2012 9:36 AM > To: Yahoo Canyons Group
    Subject: [from Canyons Group] Re: Bolt hole patch opinion


    --- In Yahoo Canyons Group <mailto:canyons%40yahoogroups.com> , "Luke" > <luke@> wrote:

    As you may have heard we have a bolt fairy installing a ton of bolts in > Red Rock. Rumor on the street is our bolt fairy has moved to Death Valley > and may have stricken a couple routes there. The problem is, all the bolts > (both in Death Valley and in Red Rock) are in places where it is illegal to > bolt.
    > Ugh! Double Ugh!
    > ...
    So if one could patch a bolt hole and make it invisible is
    that a safe thing to do? Would it be safer to make the patch blend well > for aesthetic sense but leave it at least a little obvious for safety > reasons?

    Interesting theoretical question, though in practice it is an easy question > to answer. (no problemo!)
    The "cone of sheer" analysis determines the theoretical limit of strength of > the medium into which the bolt is set, assuming a homogeneous solid. It is a > useful model, but it applies poorly to what we actually do, because > mechanical bolts rarely if ever fail this way in the field. The sheer > strength of the rock, even Navajo sandstone, is rarely the weak link in the > chain.
    It is possible to achieve the kind of bolt-rock bond that would allow for a > cone-of-sheer failure by using short, big glue-in bolts, well-installed.
    In the field, I see several problems with applying this issue:
    1. Patching holes well is difficult. Patching holes so that upon close > examination they are un-noticeable is virtually impossible. Drilling a hole > within a few inches of a patch and not noticing seems very unlikely - then > again, thinking you need bolts in RR and DV is also unlikely.
    2. In order to compromise the strength of the new bolt, the new hole would > probably have to intersect the old one, or be very, very close to it. Seems > like the driller would notice either while drilling, or while setting the > bolt.
    3. The forces we apply to the bolt while rappelling (about 500 lbs max) are > considerably below the general strength of the bolts (5000 lbs) or of the > sheer cone (10,000 lbs). Even very close to an old hole, it is unlikely to > result in failure.
    While I appreciate your concern over this issue, may I suggest that this is > one thing you can not be concerned about.
    Tom Jones MIT II-'82 BS Mechanical Engineering


    >
  6. Luke, Are the new bolts 5-piece bolts? These can be removed by hand after de-tensioning the bolt. If they are button head bolts, this means they are split-shank, and will require a crow bar to extract. My experience is that very little "cone zone" fracturing occurs when pulling split-shanks, even in a more friable substrate. As Tom said: don't worry about it. Pull'em, and document the removal date and process in case the park service should ever need to know.

    Mi dos pesos. George On Dec 2, 2012 1:06 PM, "Luke" luke@bluugnome.com> wrote:

    > **
    > Thanks for the info Tom;
    So if I am getting this right the patched hole could weaken the stress cone > if stressed to the full strength sheer cone area. But when canyoneering we > do not even come close to this rating so we never stress the system to the > point where this would be an issue.
    I did a quick (very quick not extensive) look at some ratings and the sheer > strength of the bolts seems to range from 4500 pounds to 8000 pounds > depending on bolt size, bolt material and what spec sheet you look at. I > did not look into the sheer cone and took your word for it that the sheer > cone itself is much stronger than the bolt itself (close to double).
    While rappelling under normal circumstances we may put up to 500 pounds on > the bolt which is small percentage of the forces required to stress the > bolt. And the sheer cone is much stronger than the bolt.
    Now if someone were to take a major fall on the system, a considerably > larger force could be generated. Carabiners, rope, slings, rapids, etc all > seem to have ratings in the same range or even lower than the sheer force > ratings for bolts. So if a fall were taken, the bolts are one of many > possible week links in the system (where all are close to the same rating > anyway).
    The sheer cone would still be stronger than the bolt itself under sheer > loads? Is that correct? So the sheer cone would still be much stronger > than the sheer force of the bolt even if there were a patched hole within > the sheer cone?
    After looking at it that way I see that a weakened sheer cone is still > stronger than any part of the system anyway. Unless of course as you say > the new bolt is drilled into or next to the patched hole.
    Thanks
    Luke
    P.S. - 1 Yup needing bolts in DV is a little hard to imagine. But there > could be a nemesis out there.
    P.S. - 2 Nice credentials added to the signature
    From: Yahoo Canyons Group [mailto:Yahoo Canyons Group] On Behalf > Of > TomJones > Sent: Sunday, December 02, 2012 9:36 AM > To: Yahoo Canyons Group
    Subject: [from Canyons Group] Re: Bolt hole patch opinion
    --- In Yahoo Canyons Group <mailto:canyons%40yahoogroups.com> , "Luke" > <luke@...> wrote:

    As you may have heard we have a bolt fairy installing a ton of bolts in > Red Rock. Rumor on the street is our bolt fairy has moved to Death Valley > and may have stricken a couple routes there. The problem is, all the bolts > (both in Death Valley and in Red Rock) are in places where it is illegal to > bolt.
    > Ugh! Double Ugh!
    > ...
    So if one could patch a bolt hole and make it invisible is
    that a safe thing to do? Would it be safer to make the patch blend well > for aesthetic sense but leave it at least a little obvious for safety > reasons?

    Interesting theoretical question, though in practice it is an easy question > to answer. (no problemo!)
    The "cone of sheer" analysis determines the theoretical limit of strength > of > the medium into which the bolt is set, assuming a homogeneous solid. It is > a > useful model, but it applies poorly to what we actually do, because > mechanical bolts rarely if ever fail this way in the field. The sheer > strength of the rock, even Navajo sandstone, is rarely the weak link in the > chain.
    It is possible to achieve the kind of bolt-rock bond that would allow for a > cone-of-sheer failure by using short, big glue-in bolts, well-installed.
    In the field, I see several problems with applying this issue:
    1. Patching holes well is difficult. Patching holes so that upon close > examination they are un-noticeable is virtually impossible. Drilling a hole > within a few inches of a patch and not noticing seems very unlikely - then > again, thinking you need bolts in RR and DV is also unlikely.
    2. In order to compromise the strength of the new bolt, the new hole would > probably have to intersect the old one, or be very, very close to it. Seems > like the driller would notice either while drilling, or while setting the > bolt.
    3. The forces we apply to the bolt while rappelling (about 500 lbs max) are > considerably below the general strength of the bolts (5000 lbs) or of the > sheer cone (10,000 lbs). Even very close to an old hole, it is unlikely to > result in failure.
    While I appreciate your concern over this issue, may I suggest that this is > one thing you can not be concerned about.
    Tom Jones MIT II-'82 BS Mechanical Engineering

    >
  7. Luke

    Luke Guest

    I am not sure what kind of bolts are being used but hope to find out soon. Thanks for the thoughts and good idea on documenting things just in case.

    Luke

    -----Original Message----- From: Yahoo Canyons Group [mailto:Yahoo Canyons Group] On Behalf Of George Zelenz Sent: Sunday, December 02, 2012 3:17 PM To: Yahoo Canyons Group Subject: RE: [from Canyons Group] Re: Bolt hole patch opinion

    Luke, Are the new bolts 5-piece bolts? These can be removed by hand after de-tensioning the bolt. If they are button head bolts, this means they are split-shank, and will require a crow bar to extract. My experience is that very little "cone zone" fracturing occurs when pulling split-shanks, even in a more friable substrate. As Tom said: don't worry about it. Pull'em, and document the removal date and process in case the park service should ever need to know.

    Mi dos pesos. George On Dec 2, 2012 1:06 PM, "Luke" luke@bluugnome.com> wrote:

    > **
    > Thanks for the info Tom;
    So if I am getting this right the patched hole could weaken the stress > cone if stressed to the full strength sheer cone area. But when > canyoneering we do not even come close to this rating so we never > stress the system to the point where this would be an issue.
    I did a quick (very quick not extensive) look at some ratings and the > sheer strength of the bolts seems to range from 4500 pounds to 8000 > pounds depending on bolt size, bolt material and what spec sheet you > look at. I did not look into the sheer cone and took your word for it > that the sheer cone itself is much stronger than the bolt itself (close to double).
    While rappelling under normal circumstances we may put up to 500 > pounds on the bolt which is small percentage of the forces required to > stress the bolt. And the sheer cone is much stronger than the bolt.
    Now if someone were to take a major fall on the system, a considerably > larger force could be generated. Carabiners, rope, slings, rapids, etc > all seem to have ratings in the same range or even lower than the > sheer force ratings for bolts. So if a fall were taken, the bolts are > one of many possible week links in the system (where all are close to > the same rating anyway).
    The sheer cone would still be stronger than the bolt itself under > sheer loads? Is that correct? So the sheer cone would still be much > stronger than the sheer force of the bolt even if there were a patched > hole within the sheer cone?
    After looking at it that way I see that a weakened sheer cone is still > stronger than any part of the system anyway. Unless of course as you > say the new bolt is drilled into or next to the patched hole.
    Thanks
    Luke
    P.S. - 1 Yup needing bolts in DV is a little hard to imagine. But > there could be a nemesis out there.
    P.S. - 2 Nice credentials added to the signature
    From: Yahoo Canyons Group [mailto:Yahoo Canyons Group] On > Behalf Of TomJones > Sent: Sunday, December 02, 2012 9:36 AM > To: Yahoo Canyons Group
    Subject: [from Canyons Group] Re: Bolt hole patch opinion
    --- In Yahoo Canyons Group <mailto:canyons%40yahoogroups.com> , "Luke" > <luke@...> wrote:

    As you may have heard we have a bolt fairy installing a ton of bolts
    in > Red Rock. Rumor on the street is our bolt fairy has moved to Death > Valley and may have stricken a couple routes there. The problem is, > all the bolts (both in Death Valley and in Red Rock) are in places > where it is illegal to bolt.
    > Ugh! Double Ugh!
    > ...
    So if one could patch a bolt hole and make it invisible is that a
    safe thing to do? Would it be safer to make the patch blend well > for aesthetic sense but leave it at least a little obvious for safety > reasons?

    Interesting theoretical question, though in practice it is an easy > question to answer. (no problemo!)
    The "cone of sheer" analysis determines the theoretical limit of > strength of the medium into which the bolt is set, assuming a > homogeneous solid. It is a useful model, but it applies poorly to what > we actually do, because mechanical bolts rarely if ever fail this way > in the field. The sheer strength of the rock, even Navajo sandstone, > is rarely the weak link in the chain.
    It is possible to achieve the kind of bolt-rock bond that would allow > for a cone-of-sheer failure by using short, big glue-in bolts, well-installed.
    In the field, I see several problems with applying this issue:
    1. Patching holes well is difficult. Patching holes so that upon close > examination they are un-noticeable is virtually impossible. Drilling a > hole within a few inches of a patch and not noticing seems very > unlikely - then again, thinking you need bolts in RR and DV is also unlikely.
    2. In order to compromise the strength of the new bolt, the new hole > would probably have to intersect the old one, or be very, very close > to it. Seems like the driller would notice either while drilling, or > while setting the bolt.
    3. The forces we apply to the bolt while rappelling (about 500 lbs > max) are considerably below the general strength of the bolts (5000 > lbs) or of the sheer cone (10,000 lbs). Even very close to an old > hole, it is unlikely to result in failure.
    While I appreciate your concern over this issue, may I suggest that > this is one thing you can not be concerned about.
    Tom Jones MIT II-'82 BS Mechanical Engineering

    >





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  8. rickinlo

    rickinlo Guest

    We're more or less sure it's the same group that has put some of the bolts up in Red Rocks. I suppose they might vary their method based on rock type, but the ones in Red Rocks were a mix of both 5 piece bolts and wedge style anchors.
  9. TomJones

    TomJones Guest

    below...

    --- In Yahoo Canyons Group, "Luke" <luke@...> wrote:
    Now if someone were to take a major fall on the system, a considerably larger force could be generated. Carabiners, rope, slings, rapids, etc all seem to have ratings in the same range or even lower than the sheer force ratings for bolts. So if a fall were taken, the bolts are one of many possible weak links in the system (where all are close to the same rating anyway). >

    You talking lead climbing? In lead climbing, it is not unusual to create loads up to about 1000 lbs, less likely 1500 lbs, rare to go above 2000 lbs at the top piece. Which is why climbing stuff is rated at 5000 lbs (22kN) generally, so in the worst case, at the top piece, stuff won't break (unless... A, B or C happens, which it does, but that's another topic entirely).

    Actually, none of these things are the weak link in the system. At those loads, the human body becomes the weak link in the system. The climbing system is set up so that (in theory) the gear is always stronger than the human body can tolerate.. In other words, in most cases, most or all of the gear will be intact, but the human won't. In most cases, by then, the falling human has hit a ledge or something ... not an issue. There are not all that many climbing accidents where the gear breaks. Usually it is someone rapping off the end of a rope, or letting go of the belay, or gear pulling out - rarely because the gear actually breaks.

    In canyoneering terms, the way we do things, there is rarely the opportunity to produce climbing-type forces. Yes, our ropes are static, and I realize there are few limits to human stupidity, but the way the whole system works, there is little reason to believe that forces larger than 3X body weight are produced... except when things are already well out of control.

    Tom
  10. Luke Galyan

    Luke Galyan Guest

    Thanks again.  That puts even more in perspective.  :) Luke

    You can rent the space inside my mind ..... at least until the price becomes too high. Sent from my phone....... forgive the typos.

    -------- Original message -------- From: TomJones ratagonia@gmail.com> Date: To: Yahoo Canyons Group Subject: [from Canyons Group] Re: Bolt hole patch opinion

    below...

    --- In Yahoo Canyons Group, "Luke" <luke@...> wrote:
    Now if someone were to take a major fall on the system, a considerably larger force could be generated. Carabiners, rope, slings, rapids, etc all seem to have ratings in the same range or even lower than the sheer force ratings for bolts. So if a fall were taken, the bolts are one of many possible weak links in the system (where all are close to the same rating anyway). >

    You talking lead climbing? In lead climbing, it is not unusual to create loads up to about 1000 lbs, less likely 1500 lbs, rare to go above 2000 lbs at the top piece. Which is why climbing stuff is rated at 5000 lbs (22kN) generally, so in the worst case, at the top piece, stuff won't break (unless... A, B or C happens, which it does, but that's another topic entirely).

    Actually, none of these things are the weak link in the system. At those loads, the human body becomes the weak link in the system. The climbing system is set up so that (in theory) the gear is always stronger than the human body can tolerate.. In other words, in most cases, most or all of the gear will be intact, but the human won't. In most cases, by then, the falling human has hit a ledge or something ... not an issue. There are not all that many climbing accidents where the gear breaks. Usually it is someone rapping off the end of a rope, or letting go of the belay, or gear pulling out - rarely because the gear actually breaks.

    In canyoneering terms, the way we do things, there is rarely the opportunity to produce climbing-type forces. Yes, our ropes are static, and I realize there are few limits to human stupidity, but the way the whole system works, there is little reason to believe that forces larger than 3X body weight are produced... except when things are already well out of control.

    Tom
  11. TomJones

    TomJones Guest

    --- In Yahoo Canyons Group, "Luke" <luke@...> wrote:
    > P.S. - 2 Nice credentials added to the signature


    That Sheer cone model is a basic Mechanics of Solids concept from a Mechanical Engineering sophomore course, at any engineering school in the country. Heck, if I can remember it from 35 years ago, it can't be too complicated...

    Tom
  12. aj.outdoors

    aj.outdoors Guest

    I agree with Tom. When using the proper gear, and the proper techniques; our bodies are the weak link.

    My experiences with rescue groups and reading/research show that the most common issues are human-related. Tom mentions several common ones. Raps off the end of the rope should be fairly avoidable (paying attention or putting a knot in the end of the rope), but it's surprising how often it happens. Same concept for a belayer not noticing there's not enough rope and letting it go through the belay device.

    With the diameter of ropes getting smaller and smaller, more research is being done on devices to use for belaying. There was an incident (last year I think?) where a belayer wasn't able to catch a climbing lead fall on a thin rope. If I remember right, it was around a 9mm rope (8.9?) and the belayer was using a standard ATC; I believe without gloves - but I could be wrong on these details; I don't have the info/link on that one.

    Same concept sort of applies to canyoneering, i.e. don't let your rope speed get too fast through the belay device (especially on thinner ropes), as you might not be able to stop yourself, like the person in Insomnia: http://www.paysonroundup.com/news/2011/aug/23/climber-miraculously-survives-140-foot-fall/ He was showboating, but I've seen people need a fireman belay because they were going too fast on rappel and were burning their hands (sometimes through gloves) trying to stop themselves.

    The point is, many of these can be overcome with experience/training. I also put gear pulling out under that category; as it takes experience/practice to know good gear placements. There are active devices, like cams, that have a higher tolerance for placement; but passive devices like chocks/nuts don't have as much leeway for safe placement. To some degree, advanced canyon anchors are similar - needing knowledge/practice to use safely.

    Another easily preventable one, which could cause an issue under the right circumstances is that higher forces can be placed on anchors if you use a death triangle: http://tinyurl.com/cpk6gvf

    As Tom mentions, there are situations where gear fails, but it's fairly uncommon. I can think of only a handful in over 15 years of rescue work and/or outdoor play/research. Of those, most are understandable (in hindsight), like a rope getting cut on a climbing fall which traversed over a sharp ledge: http://climbing.about.com/b/2011/03/12/accident-analysis-climber-falls-and-rope-breaks-in-eldorado-canyon.htm

    Or Todd Skinner's harness. While there is still a little mystery on that one (i.e. no chemicals were found, so it still should have held rappelling loads: http://www.jhnewsandguide.com/article.php?art_id=2198), there was definitely visual clues that the harness should have been replaced as several people commented about it; including his last/final climbing partner.

    Always good to learn from the past...

    Mostly, wanted to give folks some things to think about. As far as the bolt question, I'm in alignment with Tom. Folks with experience should be able to tell if they are putting a safe bolt in. The obvious unfortunate thing, is that not everyone putting in bolts is experienced enough to know the difference...



    --- In Yahoo Canyons Group, Luke Galyan <luke@...> wrote:
    Thanks again.  That puts even more in perspective.  :) > Luke
    > You can rent the space inside my mind ..... at least until the price becomes too high. > Sent from my phone....... forgive the typos.
    > -------- Original message -------- > From: TomJones <ratagonia@...
    Date: > To: Yahoo Canyons Group
    Subject: [from Canyons Group] Re: Bolt hole patch opinion
    below...
    --- In Yahoo Canyons Group, "Luke" <luke@> wrote:

    Now if someone were to take a major fall on the system, a considerably larger force could be generated. Carabiners, rope, slings, rapids, etc all seem to have ratings in the same range or even lower than the sheer force ratings for bolts. So if a fall were taken, the bolts are one of many possible weak links in the system (where all are close to the same rating anyway).

    You talking lead climbing? In lead climbing, it is not unusual to create loads up to about 1000 lbs, less likely 1500 lbs, rare to go above 2000 lbs at the top piece. Which is why climbing stuff is rated at 5000 lbs (22kN) generally, so in the worst case, at the top piece, stuff won't break (unless... A, B or C happens, which it does, but that's another topic entirely).
    Actually, none of these things are the weak link in the system. At those loads, the human body becomes the weak link in the system. The climbing system is set up so that (in theory) the gear is always stronger than the human body can tolerate.. In other words, in most cases, most or all of the gear will be intact, but the human won't. In most cases, by then, the falling human has hit a ledge or something ... not an issue. There are not all that many climbing accidents where the gear breaks. Usually it is someone rapping off the end of a rope, or letting go of the belay, or gear pulling out - rarely because the gear actually breaks.
    In canyoneering terms, the way we do things, there is rarely the opportunity to produce climbing-type forces. Yes, our ropes are static, and I realize there are few limits to human stupidity, but the way the whole system works, there is little reason to believe that forces larger than 3X body weight are produced... except when things are already well out of control.
    Tom

    >
  13. RSpanel

    RSpanel Guest

    If you're gonna get all technical, aren't we talking about 'shear' strength and 'shear' cone models?

    http://en.wikipedia.org/wiki/Shear_strength

    Sheer strength is what lets you jump a crevasse, sink your ice axes in the wall and hang on, if I remember my Vertical Limit climbing movie correctly.

    ...but I'm an electrical engineer.

    Climb On, Rick

    --- In Yahoo Canyons Group, "TomJones" <ratagonia@...> wrote:
    --- In Yahoo Canyons Group, "Luke" <luke@> wrote:

    > P.S. - 2 Nice credentials added to the signature

    > That Sheer cone model is a basic Mechanics of Solids concept from a Mechanical Engineering sophomore course, at any engineering school in the country. Heck, if I can remember it from 35 years ago, it can't be too complicated...
    Tom >
  14. TomJones

    TomJones Guest

  15. Luke Galyan

    Luke Galyan Guest

    I agree those placing bolts should know and have experience.  But everyone starts somewhere right?  Its good to get these conversational learning session out on public forums.  Kinda helps open the mind of future bolters.  That was another motivation for my original post......as well as me just not knowing the answer.  :)

    Luke



    You can rent the space inside my mind ..... at least until the price becomes too high. Sent from my phone....... forgive the typos.

    -------- Original message -------- From: "aj.outdoors" ajmail2011@gmail.com> Date: To: Yahoo Canyons Group Subject: [from Canyons Group] Re: Bolt hole patch opinion

    I agree with Tom. When using the proper gear, and the proper techniques; our bodies are the weak link.

    My experiences with rescue groups and reading/research show that the most common issues are human-related. Tom mentions several common ones. Raps off the end of the rope should be fairly avoidable (paying attention or putting a knot in the end of the rope), but it's surprising how often it happens. Same concept for a belayer not noticing there's not enough rope and letting it go through the belay device.

    With the diameter of ropes getting smaller and smaller, more research is being done on devices to use for belaying. There was an incident (last year I think?) where a belayer wasn't able to catch a climbing lead fall on a thin rope. If I remember right, it was around a 9mm rope (8.9?) and the belayer was using a standard ATC; I believe without gloves - but I could be wrong on these details; I don't have the info/link on that one.

    Same concept sort of applies to canyoneering, i.e. don't let your rope speed get too fast through the belay device (especially on thinner ropes), as you might not be able to stop yourself, like the person in Insomnia: http://www.paysonroundup.com/news/2011/aug/23/climber-miraculously-survives-140-foot-fall/ He was showboating, but I've seen people need a fireman belay because they were going too fast on rappel and were burning their hands (sometimes through gloves) trying to stop themselves.

    The point is, many of these can be overcome with experience/training. I also put gear pulling out under that category; as it takes experience/practice to know good gear placements. There are active devices, like cams, that have a higher tolerance for placement; but passive devices like chocks/nuts don't have as much leeway for safe placement. To some degree, advanced canyon anchors are similar - needing knowledge/practice to use safely.

    Another easily preventable one, which could cause an issue under the right circumstances is that higher forces can be placed on anchors if you use a death triangle: http://tinyurl.com/cpk6gvf

    As Tom mentions, there are situations where gear fails, but it's fairly uncommon. I can think of only a handful in over 15 years of rescue work and/or outdoor play/research. Of those, most are understandable (in hindsight), like a rope getting cut on a climbing fall which traversed over a sharp ledge: http://climbing.about.com/b/2011/03/12/accident-analysis-climber-falls-and-rope-breaks-in-eldorado-canyon.htm

    Or Todd Skinner's harness. While there is still a little mystery on that one (i.e. no chemicals were found, so it still should have held rappelling loads: http://www.jhnewsandguide.com/article.php?art_id=2198), there was definitely visual clues that the harness should have been replaced as several people commented about it; including his last/final climbing partner.

    Always good to learn from the past...

    Mostly, wanted to give folks some things to think about. As far as the bolt question, I'm in alignment with Tom. Folks with experience should be able to tell if they are putting a safe bolt in. The obvious unfortunate thing, is that not everyone putting in bolts is experienced enough to know the difference...

    --- In Yahoo Canyons Group, Luke Galyan <luke@...> wrote:
    Thanks again.  That puts even more in perspective.  :) > Luke
    > You can rent the space inside my mind ..... at least until the price becomes too high. > Sent from my phone....... forgive the typos.
    > -------- Original message -------- > From: TomJones <ratagonia@...
    Date: > To: Yahoo Canyons Group
    Subject: [from Canyons Group] Re: Bolt hole patch opinion
    below...
    --- In Yahoo Canyons Group, "Luke" <luke@> wrote:

    Now if someone were to take a major fall on the system, a considerably larger force could be generated. Carabiners, rope, slings, rapids, etc all seem to have ratings in the same range or even lower than the sheer force ratings for bolts. So if a fall were taken, the bolts are one of many possible weak links in the system (where all are close to the same rating anyway).

    You talking lead climbing? In lead climbing, it is not unusual to create loads up to about 1000 lbs, less likely 1500 lbs, rare to go above 2000 lbs at the top piece. Which is why climbing stuff is rated at 5000 lbs (22kN) generally, so in the worst case, at the top piece, stuff won't break (unless... A, B or C happens, which it does, but that's another topic entirely).
    Actually, none of these things are the weak link in the system. At those loads, the human body becomes the weak link in the system. The climbing system is set up so that (in theory) the gear is always stronger than the human body can tolerate.. In other words, in most cases, most or all of the gear will be intact, but the human won't. In most cases, by then, the falling human has hit a ledge or something ... not an issue. There are not all that many climbing accidents where the gear breaks. Usually it is someone rapping off the end of a rope, or letting go of the belay, or gear pulling out - rarely because the gear actually breaks.
    In canyoneering terms, the way we do things, there is rarely the opportunity to produce climbing-type forces. Yes, our ropes are static, and I realize there are few limits to human stupidity, but the way the whole system works, there is little reason to believe that forces larger than 3X body weight are produced... except when things are already well out of control.
    Tom

    >
  16. rging@q.com

    rging@q.com Guest

    Dang, 35 years ago? How old are you? Wait, don't tell me, there is probably a mathematical equation for that too.

    ----- Original Message ----- From: TomJones ratagonia@gmail.com> To: Yahoo Canyons Group Sent: Mon, 03 Dec 2012 00:39:34 -0500 (EST) Subject: [from Canyons Group] Re: Bolt hole patch opinion






    P.S. - 2 Nice credentials added to the signature

    ...Heck, if I can remember it from 35 years ago, it can't be too complicated...



    Tom
  17. Mike Schasch

    Mike Schasch Guest

    So this to me is another example of the way beta is presented. (Luke you've heard this all before and we've even worked on it). There are many folks that go out to do canyons without looking at any message boards. They want the beta, and they want to go! I'd love to see more beta producers out there put more LNT principles of the area directly on the beta page. If its the first thing people see, then maybe the importance will stick with them.

    An idea.

    Mike

    --- In Yahoo Canyons Group, Luke Galyan <luke@...> wrote:
    I agree those placing bolts should know and have experience.  But everyone starts somewhere right?  Its good to get these conversational learning session out on public forums.  Kinda helps open the mind of future bolters.  That was another motivation for my original post......as well as me just not knowing the answer.  :)
    Luke
  18. Luke Galyan

    Luke Galyan Guest

    I agree.  Time of working on it becomes the issue...........  Lets talk more in person again.  :) Luke

    You can rent the space inside my mind ..... at least until the price becomes too high. Sent from my phone....... forgive the typos.

    -------- Original message -------- From: Mike Schasch mikeschasch@gmail.com> Date: To: Yahoo Canyons Group Subject: [from Canyons Group] Re: Bolt hole patch opinion

    So this to me is another example of the way beta is presented. (Luke you've heard this all before and we've even worked on it). There are many folks that go out to do canyons without looking at any message boards. They want the beta, and they want to go! I'd love to see more beta producers out there put more LNT principles of the area directly on the beta page. If its the first thing people see, then maybe the importance will stick with them.

    An idea.

    Mike

    --- In Yahoo Canyons Group, Luke Galyan <luke@...> wrote:
    I agree those placing bolts should know and have experience.  But everyone starts somewhere right?  Its good to get these conversational learning session out on public forums.  Kinda helps open the mind of future bolters.  That was another motivation for my original post......as well as me just not knowing the answer.  :)
    Luke
  19. rich_rudow

    rich_rudow Guest

    Hi Luke, thanks for taking the lead on removing the bolts in DV. I would encourage you to check in with the appropriate NPS land manager first just so they know that the canyoning community is willing, ready, and able to police itself. You might see if Abby Snow can direct you to the correct DV NPS contact person.

    It's a shame when people get heavy handed in these wonderful places and potentially ruin access for the rest of us. However, in general, I've found the land managers are "less upset" when we take responsibility for the problem and fix it without requiring an expenditure of Government resources. Let me know if we (American Canyoneers) can help in some way with tools, resources, gas money, whatever ... to make this right. Huge props for stepping up.

    Thanks,

    Rich (wearing my American Canyoneers access board member hat)

    --- In Yahoo Canyons Group, Luke Galyan <luke@...> wrote:
    I agree.  Time of working on it becomes the issue...........  Lets talk more in person again.  :) > Luke
    > You can rent the space inside my mind ..... at least until the price becomes too high. > Sent from my phone....... forgive the typos.
    > -------- Original message -------- > From: Mike Schasch <mikeschasch@...
    Date: > To: Yahoo Canyons Group
    Subject: [from Canyons Group] Re: Bolt hole patch opinion
    So this to me is another example of the way beta is presented. (Luke you've heard this all before and we've even worked on it). There are many folks that go out to do canyons without looking at any message boards. They want the beta, and they want to go! I'd love to see more beta producers out there put more LNT principles of the area directly on the beta page. If its the first thing people see, then maybe the importance will stick with them.
    An idea.
    Mike
    --- In Yahoo Canyons Group, Luke Galyan <luke@> wrote:

    I agree those placing bolts should know and have experience.  But everyone starts somewhere right?  Its good to get these conversational learning session out on public forums.  Kinda helps open the mind of future bolters.  That was another motivation for my original post......as well as me just not knowing the answer.  :)

    Luke



    >
  20. TomJones

    TomJones Guest

    Totally SUPPORT!!!

    tOM

    --- In Yahoo Canyons Group, "rich_rudow" <rich_rudow@...> wrote:
    Hi Luke, thanks for taking the lead on removing the bolts in DV. I would encourage you to check in with the appropriate NPS land manager first just so they know that the canyoning community is willing, ready, and able to police itself. You might see if Abby Snow can direct you to the correct DV NPS contact person.
    It's a shame when people get heavy handed in these wonderful places and potentially ruin access for the rest of us. However, in general, I've found the land managers are "less upset" when we take responsibility for the problem and fix it without requiring an expenditure of Government resources. Let me know if we (American Canyoneers) can help in some way with tools, resources, gas money, whatever ... to make this right. Huge props for stepping up.
    Thanks,
    Rich (wearing my American Canyoneers access board member hat)
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