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  • adaycj's Avatar
    10-27-2017
    I've tried two complete systems on a few occasions. I think it's both good and bad. Like anything else I guess there are "IFs". If the tree is pretty sketchy, if there is another place that I can set another system, if I can set it all up in a reasonable time ... then it can be an advantage and likely be safer. On certain occasions also more efficient. I also have grown to like having the hardware available for a complete system backup. I'm working on a plan to cycle more consumable items through the system as they wear. It also gives me the chance to try new stuff. If it works better than the stuff I typically use great. If not as long as it isn't a big fail I can use it in the second system and just put up with it on the occasions I need it. On the other hand. The upfront costs are high. Over a long period it isn't a big deal, but proper safe gear is pretty pricey. Two sets at once is almost ridiculous. Sometimes the second system isn't practical. What's the point of using a second system if they are both in the same tree on a similar good TIP at the same height? The benefits diminish quickly. Every good climber should have a host of options when they develop a work plan, but sometimes there are better options that should be considered. A one track thought process that aims towards two systems as a default (like industrial work at height) may not be the best thing in trees. Finally there are some counter intuitive things too. Two complete systems may put the climber at more risk. What if the tree does split, barber chair, or otherwise spontaneously disassemble while a climber is aloft? Having an extra solid attachment point with a 5000#+ tensile strength attachment to the climber's saddle may become a huge liability when thousands of pounds of wood is flying around unexpectedly. What if a 1000# chunk flies straight towards the neighboring tree and a leader snags your opposite climbing line on that tree? Unlikely, I know. But this conversation was started about COD, which by its name indicates an event that wasn't planned. I think having a second system available is a good idea. It is another tool in the kit that can be potentially towards a safe efficient work plan. But when dealing with any tree that decides to come apart in places other than where I make my cuts, it requires a significant amount of planning and foresight to use a second system to drastically increase safety while at the same time not increasing risk. The problem is that sometimes the bad stuff can happen unexpectedly. Two tie offs, and a lanyard in an appropriate configuration may be better bets that can be used more consistently.
    128 replies | 5334 view(s)
  • adaycj's Avatar
    10-24-2017
    I wouldn't let any statement of mine deter you. I think the conclusion in the real world, if there is one that can be drawn, is that our TIPs need to be sturdy. I use a basal tie quite a bit, and I won't stop now. I just think that the TIP points have more force than just the suspended weight sometimes. I think some of this happens on a cinched tie in as well, with bouncing and such. It is just that the 1 times the climber's weight, or two times the climber's weight, or some number in between is not the real force to worry about. My point isn't that we should stop using basal ties, or any other established technique. In fact, I'm not sure I have a point here. I was just trying to contribute to the conversation. I did a 10 minute experiment and a 10 minute post because I thought it was relevant to the conversation. Plus I think the experiment has flaws. The friction fighting against the rope pulling like a spring is imparting at least part of the force on the TIP as a twisting force. So the scale shows forces that aren't all really pulling the TIP straight down. However, twisting might contribute to TIP failure in a tree, so maybe the twisting shouldn't be discarded. A better experiment would likely involve three load cells. One that holds up the TIP, and one on each leg. A system that could log bouncing events at an acceptable rate would be useful too. Of course even if I did a year long experiment with tens of thousands of data points, on calibrated and appropriate equipment someone would come along and tell me I violated the laws of physics, or would just choose to substitute their own misunderstandings of a complex system. It would cost me $800 to do it better and $2500 to do better than that, but likely to no greater effect. The OP was about TIP failure. There is no perfect solution. I think all of us but a few agree that basal tie can put higher forces on the TIP with everything else equal. But a branch as big as my thigh can hold a passenger car. For the much smaller ones that we do our best to evaluate and test, I think a cinch much be better. But if a basal tie vs a cinch TIP is the difference that causes a failure, I don't want to climb it.
    71 replies | 6249 view(s)
  • adaycj's Avatar
    10-24-2017
    Definition of theory from internet "an idea used to account for a situation or justify a course of action." I'm fine if you don't like my experiment. It has flaws. I'm allowed my ideas, and I'll continue to use the word theory correctly. Picking apart word choice is typically left for situations where there can be a significant misunderstanding, or situations where where words are used to demonstrate that others aren't smart enough to be part of the conversation. In this case you are right. I am not smart enough to be part of a conversation about magic. It is not about conservation of mass, it is about stored energy. A spring can pull down on something.
    71 replies | 6249 view(s)
  • adaycj's Avatar
    10-24-2017
    I tried an experiment. I'm sure the isn't in any way original. It may be apples to oranges compared to a real TIP with real world conditions. I used Sampson velocity rope over an old pull up bar in my basement. The chin up bar has two wraps of friction tape, the adhesive is towards the bar not the rope. I can "climb" Ddrt on this bar and the friction isn't noticeably different than a crotch in a tree. I "basal" tied it to a softener tank, and I used a fish scale. It is not even really science, since there are likely 100 things that could influence the numbers that are out of my control. The hypothesis. A TIP point may have more or much more than the suspended weight on it when in use. One theory is that it will have close to the suspended weight because of friction. Another theory is that it will have 2 times the suspended weight because of lever and pulley math. A final theory is that is can have more than 2 times the weight on the TIP because of friction. Step 1. Zero the 50# fish scale. Step 2. Tie and weigh the weights with fish scale. 10.60# Step 3. Rig basal tied SRT line without weights. Scale on basal side rope. 0.22# Step 3. Hand tie weights on two bights of rope 5.26# Step 4. Use a sum to estimate weight on TIP (Note: the basal side rope isn't perpendicular to the suspended weight rope, this number is off a bit) 10.60# + 5.26# = 15.86# Step 5. Pull down on the suspended rope with my hand, maybe with and additional 20# of force for 1 second and release smoothly in 1 second. No jerking, no slow release, no body weight. Step 6. Read scale stabilized scale after my hand is off the line. 23.96# Step 7. Use a sum to estimate weight on TIP (Note: the basal side rope isn't perpendicular to the suspended weight rope, this number is off a bit) 23.96# + 5.26# = 29.22# All values were taken in "static" conditions. The value was stabilized on the screen and my hands were away from the test setup. The fish scale screen only updates about every 2 seconds, there is no "peak hold" function. I made no attempt to read any values that wouldn't stay on the screen for more than 10 seconds, all reading were hands off. Conclusion: If a conclusion can be drawn from this limited test, it is that the TIP forces can be 1.5 times, 2 times, or greater than 2 times the suspended weight. Some level of mechanical advantage is at play. As I type this there is almost 3 times the suspended weight on the TIP in my basement. My opinion is that a basal tied system may expose the TIP to forces much greater than the climber's weight over an extended period of time. Sometimes much more than the approximate calculated 2:1 mechanical advantage. https://www.amazon.com/photos/share/jG5rMVdPte2lx4pCY2OhYtQlycEJpr6el2D88inereI
    71 replies | 6249 view(s)
  • adaycj's Avatar
    10-23-2017
    I'm Allen. I added my state to my profile.
    71 replies | 6249 view(s)
  • adaycj's Avatar
    10-23-2017
    Think we agree. The friction matters. I wasn't challenging your math, skills, or validity of your post. I apologize. I should have been more considerate of my phrasing. I was only stating that I have a suspicion that dynamic forces could potentially be over the 2:1 value as well a less. Sadly I don't have the equipment to collect the data to prove it. I also am approaching 20 years since my last statics course, so you used more pencil lead than I could already.
    71 replies | 6249 view(s)
  • adaycj's Avatar
    10-21-2017
    I don't have a load cell, so I can't quantify my suspicions. I think the TIP base tie can be both better or worse depending on things that may be out of the climber's control. Suppose you are basal tied with a "sticky" branch or crotch with lots of friction. The climber is 200#, but he slips and causes a 300# force on the rope for an instant. At the same time the rope slips at the TIP and catches. Now there is 150# "stuck" on the base to TIP side. With a 200# climber still on the line there is even more than double force on the TIP at least for a short time. A sizable number of climbs with recorded forces on the basal side would be useful. I agree that I have found my base to TIP line nearly slack when I have touched it while climbing. I've also noticed that it sometimes feels even more taught than the climbing line. I know the conversation is about avoiding TIP breakage, but I feel like estimating loads can only go so far. Dynamics play hell on static calculations.
    71 replies | 6249 view(s)
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