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.
free body 2pt-07
Grant Prattley

Two-Point Anchor Angles: The Simple Trig Behind the Rules

Two-Point Anchor Angles: The Simple Trig Behind The Rules Most rope courses teach an anchor angle rule. The usual version says stay under 90 degrees for two-point marginal anchors. My recommendation is tighter: keep two-point anchor angles at 60 degrees, with 45 to 60 as the sweet spot. I’ve explained why in another post. Check this out at the end. Whichever number you use, sooner or later a student asks where it comes from, and “that’s the rule” doesn’t hold

Grant Prattley 29/09/2026
webbing anchor header
Anchors
Grant Prattley

Is 16mm webbing strong enough for rescue?

The post tackles a practical question for backcountry rescue teams: is 16mm tubular webbing strong enough for anchor rigging, given the appeal of reducing weight in a rescue kit? To find out, the team ran a series of pull tests comparing different wrap-and-pull configurations — Wrap 1 Pull 1, Wrap 2 Pull 2, Wrap 2 Pull 1, and Wrap 3 Pull 2 — across several real-world surfaces: pins, carabiners, smooth rock, sharp rock, and edge-protected sharp rock. A baseline was

Grant Prattley 29/06/2026
Friction
Grant Prattley

Does a smaller radius have more friction?

The post tackles a common assumption in rope work: that a smaller-radius device — a carabiner, mallion rapide, or belay device — produces more friction on a rope than a larger one, since the rope is thought to have more internal resistance as the radius decreases. To find out if this holds up, the team ran friction tests comparing stainless steel mallion rapides at 12mm, 10mm, 8mm, and 7mm, all using the same 8mm static rope. The results are checked

Grant Prattley 25/11/2025
Which has more friction One Carabiner or Two
Friction
Grant Prattley

Which Has More Friction, One Carabiner or Two?

With rope diameters trending smaller, there’s a common claim that two carabiners create more friction than one for a Munter hitch or a belay device like the Reverso. This post tests that claim across three stages: measuring the coefficient of friction directly, running slow-pull tests on different devices, and finally trying it out on a practical 10m abseil, using both round and frame-style carabiners.

Grant Prattley 25/11/2025
6on1 VT Prusik reset
Pulley Systems
Grant Prattley

Semi-Auto Reset: A Faster Way to Reset Your Pulley System

Semi-Auto Reset Resetting a pulley system in rope rescue can eat up time and limit your throw length. This post covers the Semi-Auto Reset — attaching a cord to the travelling pulley’s rope grab so an edge person can reset the system multiple times faster than walking it out. It covers cord sizing, compatible devices and Prusiks, pulley options, and troubleshooting twists and friction. Context This post is about small team rope rescue, where 3-4 people are hauling a patient

Grant Prattley 13/03/2025
Pulley Systems 101
Pulley Systems
Grant Prattley

Pulley Systems 101: Setup, Types, MA, and Progression

Learn pulley system basics A pulley system lets you haul a rescue load up vertical or sloping terrain, from a single pulley at the anchor to multi-pulley setups for heavier loads and smaller teams. This post covers pulley system setup, the three system types (simple, compound, complex), mechanical advantage, and progression. Pulley system setup Pulley system types Simple(s) A simple pulley system is defined as ‘one continuous flow of rope, back and forth, alternating between fixed pulleys on the anchor

Grant Prattley 24/03/2024
2:1 Load Release Hitch MMO Test 8mm cord
Bends & Hitches
Grant Prattley

2:1 Load Release Hitch: does it work?

What’s in this post? We undertook testing to confirm the 2:1 Load Release Hitch rescue setup and see if it was suitable for both single and two-person loads as far as maximum force (tied off with a Munter Mule Overhand) and had enough friction for lowering during load transfer. The Load Release Hitch problem A Load Release Hitch, built with two HMS (or pear-shaped) carabiners and cord (10m of 8mm), is, for example, used for a directional pulley and passing

Grant Prattley 30/01/2024
Double sheet bend yosemite 10mm
Rigging
Grant Prattley

Double sheet bend; but it’s fine?

Testing whether the double sheet bend holds up for rescue rigging, comparing it and its backup variations against a figure-8 rethread and double fisherman’s bend.

Grant Prattley 20/05/2023
Measuring the Prusik bight
Rope Rescue
Grant Prattley

Setting up your Prusiks for Lightweight Rescue

What’s in this post? We review how to set up 8mm Prusik loops for 10mm rescue rope.  Context Prusik Loops are tied with 3-wraps (3-on-3) onto the rescue rope to form a progress capture or rope grab in a pulley system for rope rescue. Pulley system setup Prusik Cord The Prusik cord we choose to use was an 8mm 16kN Kordas Accessory Cord.  This cord is flexible and grips well onto the 10mm rope. By flexible cord I mean you

Grant Prattley 08/03/2023
single strand vs sling
Anchors
Grant Prattley

Why is a sling 2x the strength of a single strand?

What’s in this post? This post is about the theory and testing behind why making a piece of webbing into a sling is 2x the strength of a single strand. We address the specific question about tension on a single section of sling around a carabiner at the end and draw vectors to show what happens at the anchor connections. We use sling strength evidence; load cells to show the tension on the strands compared to the load and slow

Grant Prattley 31/08/2022
Lightweight Jigger Complete
Rope Rescue
Grant Prattley

Lightweight Jigger Testing

What’s in this post? Testing of a lighter weight jigger (4:1CD/5:1 pre-rigged pulley system) using a 5mm Prusik and a 6mm high strength cord made with a Dyneema core with a polyester sheath. We also address the weight and volume of a jigger to compare the lighter weight version with a standard version using a 6mm Prusik and a 8mm Nylon cord. Introduction For backcountry rescue, the aim is to use lighter weight gear balanced with functionality and performance.  A couple of

Grant Prattley 20/05/2022
webbing anchor header
Anchors
Grant Prattley

Webbing anchors: efficient rigging and 16mm testing

What’s in this post? The basics for webbing anchors: So you know why you are using webbing anchors, what to use, set up and four ways of rigging. How to rig webbing anchors efficiently: Get the right (minimum) webbing length, rather than halfway through a rigging job finding out you are short and have to start again. 16mm webbing anchor testing: Answering the question “Does 16mm tubular webbing have sufficient strength for anchor rigging in backcountry rescue?” with tests around pins, carabiners

Grant Prattley 22/04/2022
Rigging
Grant Prattley

Testing the Figure-8 Device Block for Canyoning

What’s in this post? Slow Pull testing the figure-8 device block variations with normal loading and incorrect loading. We also compare this to baseline methods such as the Munter mule overhand and figure-8 on a bight. Efficiency tests (speed) to find out if there is there any major differences in tying methods. Practical use comparisons between variations looking at the lowering, tying off functionality. Introduction Catching up with another canyoner recently they showed me a failure method for a particular

Grant Prattley 31/12/2021

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