“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.

A Young Persons Guide to Tracking Elements in Offsets and Highlines

A Presentation by Reed Thorne

Presentation #2 for the 2007International Technical Rescue Symposium

A Young Persons Guide toTracking 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.

Track Lines:Force delivered by mass is shared

between the main line and the track line

100 kg

Carriage

Belay Line

Lower Tag Line

Track Line

Track Line

Upper Tag Line

1

2

3

100 kg

Carriage

1000 Nforce vector

Belay Line

Lower Tag Line

Track Line

Track Line

Upper Tag Line

Track Lines:Force delivered by mass is shared

between the main line and the track line

100 kg

Lower Tag Line

Track Line

1000 Nforce vector

Carriage

1000 Nforce vector

Belay Line

Track Line

Upper Tag Line

100 kg1000 Nforce vector

1000 Nforce vector

Carriage

Belay Line

Lower Tag Line

Track Line

Track Line

Upper Tag Line

4

5

6

100 kg1000 Nforce vector

550 Nforce vector

Carriage

1000 Nforce vector

Belay Line

Lower Tag Line

Track Line

Track Line

Upper Tag Line

100 kg1000 Nforce vector

1000 Nforce vector

550 Nforce vector

1450 Nforce vector

Carriage

Belay Line

Lower Tag Line

Track Line

Track Line

Upper Tag Line

100 kg

1000 Nforce vector

550 Nforce vector

1450 Nforce vector

MustBe

Equal

Tension on one side of a pulley must be the same on the other

Belay Line

Lower Tag Line

Track Line

Track Line

Upper Tag Line

7

8

9

100 kg

1000 Nforce vector

Belay Line

Lower Tag Line

Track Line

Track Line

Upper Tag Line

550 Nforce vector

1450 Nforce vector

MustBe

Equal

1450 N– 550 N

100 kg

1000 Nforce vector

550 Nforce vector

1450 Nforce vector

MustBe

Equal

900 Nforce vector

1450 N– 550 N

Belay Line

Lower Tag Line

Track Line

Track Line

= 900 N

Upper Tag Line

100 kg

1000 Nforce vector

550 Nforce vector

900 Nforce vector

Belay Line

Lower Tag Line

Track Line

Track Line

Upper Tag Line 550 Nforce vector

Now are Equal!

10

11

12

100 kg

Belay Line

Track Line

Track Line

Upper Tag Line

Carriage

Track Lines:As angle increases, track line

force increases

100 kg

Belay Line

Track Line

Track Line

Upper Tag Line

Carriage

Track Lines:As angle increases, track line

force increases

100 kg

Belay Line

Track Line

Upper Tag Line

Carriage BEWARE!

New Track Line Position

Track Lines:As angle increases, track line

force increases

13

14

15

100 kg

Belay Line

Track Line

Upper Tag Line

Carriage

Track Line

1000 Nforce vector

100 kg

Belay Line

Track Line

Upper Tag Line

Carriage

Track Line

1000 Nforce vector

1000 Nforce vector

100 kg

Belay LineUpper Tag Line

Carriage

Track Line

1000 Nforce vector

1000 Nforce vector

16

17

18

100 kg

Belay LineUpper Tag Line

Carriage

Track Line

1000 Nforce vector

1000 Nforce vector

950 Nforce vector

100 kg

Belay LineUpper Tag Line

Carriage

Track Line

1000 Nforce vector

1000 Nforce vector

950 Nforce vector

1850 Nforce vector

100 kg

Belay LineUpper Tag Line

Carriage

Track Line

1000 Nforce vector

950 Nforce vector

1850 Nforce vector

MustBe

Equal

19

20

21

100 kg

Belay LineUpper Tag Line

Carriage

Track Line

950 Nforce vector

MustBe

Equal

1850 N– 950 N

1850 Nforce vector

1000 Nforce vector

100 kg

Belay Line

Track Line

1000 Nforce vector

950 Nforce vector

1850 Nforce vector

MustBe

Equal

1850 N– 950 N

900 Nforce vector

= 900 N

Upper Tag Line

100 kg

Belay Line

Track Line

1000 Nforce vector

950 Nforce vector

Now are Equal!

900 Nforce vector

Upper Tag Line 950 Nforce vector

22

23

24

1000 Nforce vector

550 Nforce vector

1000 Nforce vector

950 Nforce vector

900 Nforce vector

Compare Forces?

900 Nforce vector

1000 Nforce vector

550 Nforce vector

1000 Nforce vector

950 Nforce vector

900 Nforce vector

900 Nforce vector

Upper taglines: Tension remains relatively constant

Compare Forces?

Trackline: Tension increases with greater angle

1000 Nforce vector

550 Nforce vector

1000 Nforce vector

950 Nforce vector

900 Nforce vector

Compare Forces?

900 Nforce vector

Really, this is the inherent difference between steep highlines and the tracking line offset....

25

26

27

comparisons w/offsets

comparisons w/offsets

Guiding Lines

Tracking Lines

Steep Highlines

Tracking Line

Track Line

Guiding Line

Principle differences between the Offsets and the Highline

Main Line

Main Line

Tag Line

Tag Line

Belay Line

Belay Line

Belay Line (optional)

Guiding Line Tracking Line Steep Highline

Tension Differences in Guiding, Tracking and

Track lines

28

29

30

Tracking Line

Track Line

Guiding Line

Principle differences between the Offsets and the Highline

Guiding Line Tracking Line Steep Highline

Tension Differences in Guiding, Tracking and

Track lines

Tracking Line

Track Line

Guiding Line

Principle differences between the Offsets and the Highline

Main Line

Main Line

Tag Line

Tag Line

Belay Line

Belay Line

Belay Line (optional)

Guiding Line Tracking Line Steep Highline

Tension Differences in Main Lines and Upper

Tagline

Principle differences between the Offsets and the Highline

Main Line

Main Line

Tag Line

Guiding Line Tracking Line Steep Highline

Tension Differences in Main Lines and Upper

Tagline

31

32

33

Tracking Line

Track Line

Guiding Line

Principle differences between the Offsets and the Highline

Doubled long-tailed bowline

Optional guiding line tether

Main Line

Main Line

Tag Line

Tag Line

Belay Line

Belay Line

Belay Line (optional)

Single long-tailed bowline

Doubled long-tailed bowline with belay, otherwise single long-tailed

bowline

Guiding Line Tracking Line Steep Highline

Tracking Line

Track Line

Guiding Line

Principle differences between the Offsets and the Highline

Small Pulley

Main Line

Main Line

Tag Line

Tag Line

Belay Line

Belay Line

Belay Line (optional)Kootenay Carriage

Guiding Line Tracking Line Steep Highline

comparisons w/offsets

Two rope Offsets

Drooping Highlines

34

35

36

Track Line

Drooping Highline

Left Main Line Right Main Line

Left Tagline Right TaglineTrack

LineTwo Rope Offset

Left Belay LineRight Belay L

ine

Principle differences between the Offsets and the Highline

At mid-span

Track Line

Principle differences between the Offsets and the Highline

Two Rope Offset

Drooping Highline

Left Main Line Right Main Line

Left Tagline Right TaglineTrack

Line

Single long-tailed bowlines each

side

Multi directional ring with doubled

long-tailed bowlines each

side

Kootenay Carriage

Left Belay LineRight Belay L

ineAt mid-span

Track Line

Drooping Highline

Left Main Line

Left Tagline

Two Rope Offset

Left Belay Line

Principle differences between the Offsets and the Highline

Near each station

Righ

t Main

Line

Righ

t Tag

line

Trac

k Line

Righ

t Bela

y Line

37

38

39