Reed Thorne
“A Young Persons Guide to Tracking Elements in Offsets and Highlines” Presented by: Reed Thorne “A Young Persons Guide to Tracking Elements in Offsets and Highlines” Many times I am asked when a track line becomes a tracking line or a guiding line. While the answer is not cut and dry, nor black and white, there are things going on in the tracking elements that bear mention. This presentation goes into a diagrammatic explanation using force vector analysis of steep highlines and the subtle symbiosis as it were between the upper tag line and the track line. As the highlines track line increases in steepness the tracking elements tensile force drops off significantly until it becomes basically a tracking line or guiding line within the realm of the high angle offset (see presentation #1). Conversely, as the highline becomes less steep it takes on more of the tension force between the anchors and the tag lines see less and less. In the case of a horizontal highline, this can then explain why we see more force in the centre of a highline than at each end as we begin to see the taglines holding some of this whilst the suspended mass is near each side. This presentation will provide some informative base line understanding and critical thinking on what is going on with respect to tracking element tension at various angles within highlines and high angle offsets. About the Presenter Reed Thörne grew up in Southern California where he became involved with the Sierra Club Rock Climbing and Mountaineering Sections as an instructor/leader. He now runs Ropes That Rescue Ltd., a rigging school in the rugged highland regions of northern Arizona near the town of Sedona. RTR teaches roped disciplines including rope rescue, rope access and general rigging to emergency providers and industry however, their specialty is energized power transmission line rescue. RTR’s work was featured in the History Channel “Suicide Missions” special HIGH VOLTAGE in 2000 with Georgia Power Company. Reed comes from a 1970’s California lineman background where he learned rigging from various master mechanics of the trade. Later, after moving to Arizona with his wife in 1979, Reed became involved with Butch “Charles” Farabee or the National Park Service who worked at the Grand Canyon National Park in the early 80’s. Beginning in 1981, Reed became instrumental in the foundation of the Sedona Fire Department Mountain Rescue Team and eventually Battalion Chief for the Special Ops Section (helicopter, swiftwater and rope rescue). For one week in 1989, Reed, John Dill or Yosemite SAR, and Arnor Larson of the BCCTR performed the “Sedona Drop Tests” at the Sedona Fire Department. These tests formed some of the initial foundation for the use of the tandem prusik belay around the world today. Reed Thorne regularly holds rigging and rescue programs in the USA, Canada, Australia and New Zealand each year. At this years ITRS, RTR has three of its instructors attending: Len Batley from Australia, Kevin Frye from Los Angeles County Fire, Dave Van Holstyn from Grand Rapids (MI) Fire and Eric Ulner from Vertical Heartland Climbing School. Presentation #2 for the 2007 International Technical Rescue Symposium A Young Persons Guide to Tracking Elements in Offsets and Highlines A Presentation by Reed Thorne 1 A Young Persons Guide to Tracking Elements in Offsets and Highlines By Reed Thorne: Ropes That Rescue Ltd. Sedona, AZ USA Many times I am asked when a track line becomes a tracking line or a guiding line. While the answer is not cut and dry, nor black and white, there are things going on in the tracking elements that bear mention. This presentation goes into a diagrammatic explanation using force vector analysis of steep highlines and the subtle symbiosis as it were between the upper tag line and the track line. As the highlines track line increases in steepness the tracking elements tensile force drops off significantly until it becomes basically a tracking line or guiding line within the realm of the high angle offset (see my presentation #3). Conversely, as the highline becomes less steep it takes on more of the tension force between the anchors and the tag lines see less and less. In the case of a horizontal highline, this can then explain why we see more force in the centre of a highline than at each end as we begin to see the taglines holding some of this whilst the suspended mass is near each side. This presentation will provide some informative base line understanding and critical thinking on what is going on with respect to tracking element tension at various angles within highlines and high angle offsets. 2 k Trac Line ine L Tag per Up Line lay Be Track Lines: Force delivered by mass is shared between the main line and the track line Carriage 100 kg Lo we rT ag Tr a ck Lin e Lin e 3 k Trac Line ine L Tag per Up Line lay Be Track Lines: Force delivered by mass is shared between the main line and the track line Carriage 100 kg 1000 N force vector Lo we rT ag Tr a ck Lin Lin e e 4 k Trac Tag per Up Line lay Be Line e Lin 1000 N force vector Carriage 100 kg 1000 N force vector Lo we rT ag Tr a ck Lin Lin e e 5 k Trac Line ine L Tag per Up Line lay Be 1000 N force vector Carriage 1000 N force vector 100 kg Lo we rT ag Tr a ck Lin e Lin e 6 k Trac Line ine L Tag per Up Line lay Be 1000 N force vector 550 N force vector Carriage 100 kg 1000 N force vector Lo we rT ag Tr a ck Lin Lin e e 7 k Trac Tag per Up Line lay Be Line e Lin 1450 N force vector 1000 N force vector 550 N force vector Carriage 100 kg 1000 N force vector Lo we rT ag Tr a ck Lin Lin e e 8 k Trac Line ine L Tag per Up Line lay Be 1450 N force vector Must Be Equal 1000 N force vector 550 N force vector 100 kg Tension on one side of a pulley must be the same on the other Lo we rT ag Tr a ck Lin e Lin e 9 k Trac Line ine L Tag per Up Line lay Be 1450 N force vector Must Be Equal 1000 N force vector 550 N force vector 1450 N – 550 N 100 kg Lo we rT ag Tr a ck Lin Lin e e 10 k Trac e Lin Line Tag per Up Line lay Be 1450 N force vector Must Be Equal 1000 N force vector 900 N force vector 550 N force vector 1450 N – 550 N 100 kg = 900 N Lo we rT ag Tr a ck Lin Lin e e 11 k Trac Line ine L Tag per Up Line lay Be 550 N force vector Now are Equal! 1000 N force vector 900 N force vector 550 N force vector 100 kg Lo we rT ag Tr a ck Lin e Lin e 12 k Trac Line ine L Tag per Up Line lay Be Track Lines: As angle increases, track line force increases Carriage 100 kg Tr a ck Lin e 13 k Trac Tag per Up Line lay Be Line e Lin Track Lines: As angle increases, track line force increases Carriage 100 kg Tr a ck Lin e 14 k Trac Line ine L Tag per Up Line lay Be Track Lines: As angle increases, track line force increases Carriage BEWARE! 100 kg w Ne ck a Tr eP Lin n itio os 15 k Trac Line ine L Tag per Up Line lay Be Carriage 100 kg 1000 N force vector ine kL ac Tr 16 k Trac Tag per Up Line lay Be Line e Lin 1000 N force vector Carriage 1000 N force vector 100 kg ck a Tr e e Lin Lin 18 ine L Tag per Up Line lay Be 17 1000 N force vector Carriage 1000 N force vector 100 kg k ac Tr ine L Tag per Up Line lay Be 1000 N force vector Carriage 950 N force vector 1000 N force vector 100 kg kL ac Tr ine 19 Tag per Up Line lay Be e Lin 1850 N force vector 1000 N force vector Carriage 950 N force vector 1000 N force vector 100 kg ck a Tr Lin e 20 ine L Tag per Up Line lay Be 1850 N force vector Must Be Equal 1000 N force vector Carriage 950 N force vector 100 kg k ac Tr e Lin 21 ine L Tag per Up Line lay Be 1850 N force vector Must Be Equal 1000 N force vector Carriage 950 N force vector 1850 N – 950 N 100 kg kL ac Tr ine 22 Tag per Up Line lay Be e Lin 1850 N force vector Must Be Equal 1000 N force vector 900 N force vector 950 N force vector 1850 N – 950 N 100 kg = 900 N ck a Tr Lin e 23 ine L Tag per Up Line lay Be 950 N force vector Now are Equal! 1000 N force vector 900 N force vector 950 N force vector 100 kg k ac Tr e Lin 24 Compare Forces? 1000 N force vector 1000 N force vector 900 N force vector 900 N force vector 950 N force vector 550 N force vector 25 Compare Forces? Upper taglines: Tension remains relatively constant 1000 N force vector 1000 N force vector 900 N force vector 900 N force vector 950 N force vector 550 N force vector 26 Compare Forces? Trackline: Tension increases with greater angle 1000 N force vector 1000 N force vector 900 N force vector 900 N force vector 950 N force vector 550 N force vector Really, this is the inherent difference between steep highlines and the tracking line offset.... 27 comparisons w/offsets 28 comparisons w/offsets Guiding Lines Tracking Lines Steep Highlines 29 l) ine na kL tio ac Tr Line (op g ne Ta Li lay Be Line king Trac Line Main ine yL Bela Line Guiding e in Main L e Lin Belay Principle differences between the Offsets and the Highline Tension Differences in Guiding, Tracking and Track lines Ta g Guiding Line Tracking Line Steep Highline Li ne 30 ine ine ine ing L kL ac Tr k Trac L Guiding Guiding Line Principle differences between the Offsets and the Highline Tension Differences in Guiding, Tracking and Track lines Tracking Line Steep Highline 31 l) ine na kL tio ac Tr Line (op g ne Ta Li lay Be Line king Trac Line Main ine yL Bela Line Guiding e in Main L e Lin Belay Principle differences between the Offsets and the Highline Tension Differences in Main Lines and Upper Tagline Ta g Guiding Line g Ta Main e Lin Line ine Main L Guiding Line Tracking Line Steep Highline Li ne 32 Principle differences between the Offsets and the Highline Tension Differences in Main Lines and Upper Tagline Tracking Line Steep Highline 33 l) ine na kL tio ac Tr Line (op g ne Ta Li lay Be Line king Trac Line Main ine yL Bela Line Guiding e in Main L e Lin Belay Doubled longtailed bowline Optional guiding line tether Principle differences between the Offsets and the Highline Doubled longtailed bowline with belay, otherwise single long-tailed bowline Single long-tailed bowline Ta g Guiding Line Tracking Line Steep Highline l) ine na kL tio ac Tr Line (op g ne Ta Li lay Be Line king Trac Line Main ine yL Bela Line Guiding e in Main L e Lin Belay Kootenay Carriage Ta g Tracking Line 34 Principle differences between the Offsets and the Highline Small Pulley Guiding Line Li ne Steep Highline Li ne 35 comparisons w/offsets Two rope Offsets Drooping Highlines 36 Principle differences between ft the Offsets and the Highline Le M ft ain Be Lin lay At mid-span e Le Lin e tM gh Be i R ht g Ri Tr Offset Two Rope ac k Lin Le e Lin e Lin lay ain ine kL c a e Tr lin ag T t gh Ri e ft T ag li ne Drooping Highline 37 Principle differences between ft the Offsets and the Highline Le M ft ain Be Lin lay At mid-span e Le Lin e Two Rope Offset Tr ac kL ft T ine ag lin e Drooping Highline e Lin e Lin lay tM gh Be i R ht g Ri Multi directional ring with doubled long-tailed bowlines each side Le ain ine kL c a e Tr lin ag T t gh Ri Single long-tailed bowlines each side Kootenay Carriage Two Rope Offset Lef tM a Lef t Be in Lin lay e Line Tra c Left kL ine Tag li Rig Principle differences between the Offsets and the Highline Near each station Rig Rig T ht B ht M ht T rack ela agl Lin y L ain Li ine e ine ne 38 ne Drooping Highline 39
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