BLOG ARCHIVE — IDEAS THAT HOLD UNDER LOAD

Rope. Rigging. Reason

Where field craft meets first principles — every technique stress-tested by maths, every system shaped by research, every team lifted by clear leadership.
Canyon rescue testing two rope
Canyoning
Grant Prattley

Canyon Rope Rescue Testing

Canyon Rope Rescue Testing 2021 In February 2019, a team of people from the NZ Canyoning Association got together for a weekend to discuss setting up CanyonSAR for New Zealand (as a specialist discipline under New Zealand Land SAR). As part of this weekend, we discussed and practised rope rescue in the canyoning context with training as a focus. Out of this discussion and practice came: The types of rope rescues we were likely to do? Who are the rescuers,

Grant Prattley 30/08/2021
thread testing setup
Rigging
Grant Prattley

Rock Thread and V-thread Testing 2021

What’s in this post? The question we are going to answer in this post is: When you drill a hole through a rock and thread a cord what is the best setup for bends, cord and rock strength. We have used an 8mm Nylon cord for cave rescue and a 6mm Dyneema cord for canyoning and caving recreational anchor building. It was time to find out the performance of these two cords and several others. Keep reading to find out the

Grant Prattley 15/08/2021
blog post header inline anchor testing
Rigging
Grant Prattley

Webbing in hangers

Webbing in hangers The question we are going to answer in this post is: Is it ok to rig using webbing directly into new bolt hangers? I have rigged and used both inline and two-point anchors in a canyoning situation for years and never had any reason to be concerned.  However, it was time to put some testing behind the practice. Keep reading to find out the results, AND you get to download a detailed testing report at the end. Introduction

Grant Prattley 19/06/2021
RRRFG pg 65 backtie rigging
Rigging
Grant Prattley

Back-tie rigging – tension and compression forces

Back-tie rigging – tension and compression forces The other day I had a question come through about how I worked out the tension and compression forces for a post, pole or tree when you back-tie for support.  The context? Before I get to the question, we need to set the context:  The front anchor is in the right location; however, it needs a back anchor to make it acceptable with sufficient margin. The back anchor is some distance from the

Grant Prattley 10/05/2021
Two Rope Drop Testing 2
Rope Rescue
Grant Prattley

Let’s lighten the load – update

Let’s lighten the load – Update. After a particularly arduous 24hrs underground and 1000m of hauling on a deep cave SAREX (Search And Rescue EXercise), we started our journey towards asking the right questions about rope rescue. Could we lighten up our backcountry rope rescue gear while keeping acceptable safety margins? For lightweight rope rescue, one of the first things we considered was a smaller diameter rope. Two immediate questions arose: Would we be able to find equipment to work

Grant Prattley 27/02/2021
2 point floating anchor carabiner pulleys
Anchors
Grant Prattley

Floating anchors: But what if the anchor blows?

Introduction Floating anchor: but what if the anchor blows? Isn’t it going to rip the other anchor out? I hear this as a common statement when discussing a two-point floating anchor (aka self-equalising, equalette, magic X, sliding X, quad, etc.). I can only think it’s based on the assumption you have: Built or chosen poor anchors Rigged the anchors together in a way that does not share the load between the two and As one anchor fails and dynamically loads

Grant Prattley 01/02/2021
double overhand flat bend in use
Canyoning
Grant Prattley

Which bends for joining ropes? – Update

Introduction As part of writing the Canyoning Technical Manual, I needed to find out more about flat bends. For my own peace of mind, I had to make sure what I was putting in the book was suitable. We undertook some testing in 2015 including a control test and five flat (offset) bend variations.  In 2020, we redid all the above tests. We also included another 3 control tests and 7 more flat bend variations. We were interested to test the

Grant Prattley 14/10/2020
Friction Testing
Rope Rescue
Grant Prattley

How much friction for your device?

How much friction for your device? We were interested to know how much a lowering device can hold for rescue in particular and personal use. The testing is for practical use when out on a rescue, training or instructing a group about how much it can hold in relation to: the particular device the friction range minimum and maximum for the friction setting mode The keyword to think about here is ‘guide.’ We can’t give a definitive number and say

Grant Prattley 01/10/2020
Edge Kit 4on2 Drop Test Factor 1
Rope Rescue
Grant Prattley

Life on the edge: testing the edge kit

Introduction We have used an edge kit for several years. Over this time, I have never done any testing on the combination of Purcell Prusik (Prusik on a Prusik), Prusik hitch 6mm on 8mm cord and double overhand (scaffold) hitch onto a carabiner. There has also been an assumption made that the edge kit would provide some shock absorption if you did take a fall. Over the last year, we undertook some drop and slow pull testing (n=126) in 3

Grant Prattley 10/09/2020
Canyoning
Grant Prattley

Time to meat human anchors

Time to meat Human Anchors A temporary human (meat) anchor is used in sports such as caving and canyoning, to get the first or all but the last person down, using a person (or people) that is suitably positioned in a stance where they can use the friction of rope on the rock, their own mass and their legs to provide sufficient anchoring. This technique needs to be well managed and can provide safe and efficient travel through terrain that

Grant Prattley 24/08/2020
Rope Rescue
Grant Prattley

Forces on an inclined plane and Tippy the tip truck

Forces on an inclined plane and Tippy the tip truck How do you figure out the forces is a common question I get when teaching a particular subject. None more so than those on an inclined plane (or slope). Rather than getting onto the whiteboard to explain, from time to time, I bring out Tippy the tip truck. A few years ago, in the middle of winter, right before teaching a slope lowering course, I had an idea of how to

Grant Prattley 10/12/2019
Stacked Pulleys
Pulley Systems
Grant Prattley

Pulley system progression: is it worth it in practice?

A pulley system progression means stepping up from a smaller mechanical advantage — say a 3:1 simple — to a larger one, like a 5:1 or 9:1 compound, as a haul gets harder. This post tests whether that progression is actually worth it in practice, using load cells to compare the predicted force reduction at 90% pulley efficiency against what haulers really felt, and checks whether some systems in the progression turn out more efficient than others.

Grant Prattley 25/11/2019
Vlad-wear-and-tear
Canyoning
Grant Prattley

Vlad to help – a master carabiner

Vlad to help – a replacement for the master carabiner Back in November 2018, I decided to purchase a Grivel Vlad and put it on my harness to see if it was going to be a useful addition. The Vlad could be helpful as a master carabiner for anchor station organisation for multiple clip-ins. There are often many things clipped in at an anchor station such as a cows tail, safety line, packs and operational items such as releasable systems and

Grant Prattley 27/02/2019
Canyoning
Grant Prattley

The Perfect Storm

The perfect storm – keep an eye on your rigging We were on a canyoning trip recently when we were using a figure-8 abseil device as a block. Over the last eight years, I have probably rigged it over 500 times and never had an issue. However, on this occasion, all the holes in the Swiss cheese nearly aligned until we got down to the final defence – the safety check. Hold on don’t abseil yet, that doesn’t look right. At

Grant Prattley 05/11/2018
Rope Rescue
Grant Prattley

Jigger Setup: Troubleshooting

Jigger Setup: Troubleshooting As we head around various rescue groups, we find many jiggers (aka a set of fours) rigged incorrectly or operating inefficiently. Despite leaving everything in good working order, we often come back at a later time and see the jigger fairies have come in and made a mess. To illustrate my point, below is a picture from a recent Facebook post ‘one of these things is not like the other’. (see ‘Reason 2’) To help people out, I

Grant Prattley 17/08/2018

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