Rope and Gear Testing

 Tom Moyer's Testing Page

We often pull test rescue gear in mountain rescue. Testing to failure helps us understand the limitations of our gear. There's nothing quite like watching the parts fly to give you respect and caution for the forces that can make the same thing happen in the field.

I also occasionally do pull-testing of my own to satisfy my curiosity about one climbing issue or another.

 Recent Work

vRigger Force Calculations

Save an additional $50 off the retail price when you access the vRigger website from this page.

The RescueRigger program is now named vRigger (Virtual Rigger) since many people are now using the software in other rigging industries besides rescue. Whether you perform mountain, swiftwater, industrial or urban rescue, or work in the industrial, rope access, or theatrical rigging industries, vRigger will help you design and illustrate your rigging systems.

vRigger calculates the forces in your systems with a click of your mouse. The force calculations include mechanical advantage, friction, breaking strength, safety factors, and much more.

The force calculations understand the complexities of friction, ratchets, and winches, the difference between raising and lowering, and rope angles. For example, the forces on this typical 3:1 system are much different when raising than when lowering (when the "ratchet" Prusik holds the load).

Although vRigger cannot solve every system, it can solve amazingly complicated systems.

305 pieces of gear are now available in vRigger and more pieces are automatically downloaded as they are released. You can also use the Gear Builder to add your own.

Click here to learn more about vRigger and take $50 off the price. 

Rescue Physics 

"Rescue Physics" is a reintroduction to freshman physics from the perspective of rope-rescue systems. This presentation was given at the 2007 Mountain Rescue Association Conference.

Statics and Vectors are used to calculate forces in haul systems, anchors, highlines, direction changes, and litter teams.

Physics presentation (ppt format - 6M)  Physics presentation (pdf format - 3M)



Simulation of Climbing and Rescue Belays

This simulation was written to try to understand the gripping requirements for "manual" belay techniques in both rescue and climbing situations.

Previous studies of human grip strength have shown a wide range of gripping ability.

This simulation includes nonlinear rope, knots, damping, carabiner and belay device friction, slipping in the belayer's hand, and lifting of the belayer.

Simulation of Belays presentation (pdf -7M)


  Older Testing

Shiva Telemark Binding Tester at Black Diamond September, 2003

Shiva is a pneumatically powered fatigue-testing machine capable of cycling to failure any currently available telemark binding.

Shiva Video (3.4 Meg).

Highline Drop-Testing  September, 2000

We loaded up a litter with 220 pounds of rocks on a Tyrolean over Ferguson Canyon and cut the main line to test whether a tag-line belay is effective. Download the videos to see the results

Drop #1 video (1.2 Meg) Drop #2 video (1.2 Meg) 

Comparative Testing of High Strength Cord - November, 2000

How strong is that cordelette? Some of the "high-strength" cords - aren't.

This paper was presented at the 2000 ITRS symposium in Tucson, AZ.

Cord-Test paper (pdf ) Test data (Microsoft Excel)

Euro Death-Knot (aka Flat Overhand) Testing - November, 1999

Is this a death-knot? Or is it a good knot for joining rappel ropes? I got curious, so I decided to do some testing.

I pull-tested the flat-overhand, the flat figure-eight, and the double-fisherman's. EDK test results.

Water-Knot Testing- March, 1999

Water-knots gradually slip - or "ratchet" under cyclic loading.

This paper was presented at the 1999 ITRS symposium.

Water-Knot paper (pdf)

Qualifying a Rescue Rope - July, 1999

Cut and abrasion testing of static ropes and webbing.

This paper was presented at the 1999 ITRS symposium.

Rope paper (pdf)

SLCo SAR Pull-Test Session - November 1998

Quick look testing of various knots and rescue gear.

11/98 test results

 MRA Intermountain Recert Pull-Test Session July, 2000

More quick look testing.

7/00 test results

all information on these pages is copyright Tom Moyer. Please do not republish without permission. Thank you.

Last Updated on 4/8/11 By Tom Moyer