Reasons why jiggers don’t perform as well as they should

by | Aug 17, 2018 | Rope Rescue |

Reasons why jiggers don’t perform as well as they should

As we head around various rescue groups, we find many jiggers (aka a set of fours) are rigged incorrectly or operate 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 here 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 thought it would be good to pass on some troubleshooting ideas for when jiggers don’t work. Also, there is a download at the end for you on how to set up your jigger.

What is a jigger?

Jiggers are used for several rescue and rigging tasks including pickoffs, stretcher rigging, attendant positioning, directionals, back-tie tensioning between anchors, passing bends as well as a ready-made haul system.

Notes: (1) To give this post context it is mostly about a jigger you make up yourself and not one you buy premade from a manufacturer (more on this at the end). (2) This post is my personal opinions about jiggers based on 18 years of using them in training as well as in real rescue.

The reasons why they don’t perform (sometimes)

Reason 1:

It is very common to find jigger cords twisted. This twisting means there is extra friction and the pulley system is not very efficient. Either caused by:

  1. Initial jigger setup with the pulleys rigged on the same plane or
  2. The jigger is stored partially or fully extended. This storage means one of the pulleys can fall inside the cords and create a twisted mess.

Solution: (1) When you set up the jigger, rig with the pulleys at 90 degrees to each other and place the cord in alternating sheaves on the same side or top and bottom (as shown below). (2) When you store jiggers, make sure you collapse them to their smallest extent. (3) If you find a mess, you can usually figure out how to untwist it. Occasionally you will need to de-rig and start again.

Reason 2:

The load capture Prusik is in the wrong place either on the wrong side or the wrong line (see the first picture in this post). It is common to find the load capture on the first line [1] as you might do for a pulley system pulling up a rescue load. For this style of a jigger, the Scaffold hitch can interfere with the load capture Prusik on the fourth line [4].

Solution: Put load capture the Prusik on the third line [3] on the side opposite to the Scaffold Hitch. This placement means the load capture Prusik only takes a third of the tension.

Reason 3:

Choosing an unsuitable progress capture for the intended tasks. Commonly you see:

  • Using a three wrap or 6 coil (3 on 3) progress capture Prusik doesn’t work very well as it binds up.
  • As we use the jigger at times for system loads (where we expect it to be able to hold 15kN+), testing has shown in some cords (Edelrid and PMI) the 3 on 2 Prusik may slip at low loads and be quite variable. See the post HERE.

Solution: Use a six coil Prusik 4 on 2. Make sure the 2 coil part is next to the pulley, and the 4 coil is away. (See the ‘Guide: How to Build a Jigger’ for the tying method at the end of this post.)

Reason 4:

You can affect efficiency and performance by not choosing the right materials for the task. The main issues I have found are:

  • Progress capture Prusik cord is too stiff and doesn’t bind automatically on reset.
  • The jigger cord is too soft, and the sheath is not bonded well to the core. Sometimes the cord is too shiny and won’t allow the 6mm Prusik to grip as well as it should.
  • Using inefficient pulleys means the jigger is very hard to haul under load.

Solution: Be particular about the materials you are using for the job. (1) Progress capture Prusik cord needs to be softer, so it folds easily in half. (2) The jigger cord needs to have the sheath well bonded to the core. (3) Use high-efficiency pulleys (e.g. ball bearing) with alloy sheaves (see examples below).

Grant Prattley
Grant Prattley

Instructor, Designer, Consultant, Guide, Author and Adventurer

at Over The Edge Rescue.

Reason 5:

Combining the jigger with an edge kit is not a preferred solution. An edge kit is a personal piece of gear, and the jigger is most often team gear. If rescuers or riggers are wearing/using their edge kit, they are unwilling to give it up. If you have a jigger on one end, it is trapped and has limited use for other things.

Solution: Have the jigger by itself as a stand-alone tool.

Reason 6:

Having a jigger in a bumbag or just coiled rope is not a preferred solution. As I said above the jigger is more of team rescue gear, therefore, no need to have it in a bumbag. With a bumbag, the waist strap is difficult to use, difficult attach to anything easily and more difficult to pack cord. With no bag at all, although lightweight, is messy and can be harder to use.

Solution: Use an upright style pod bag that can be clipped to a harness, stretcher or anchor. It is much easier to access and pack cord.

Reason 7:

The jigger cord is the wrong length for the purpose. The length depends on the intended use. Most of the time a 10-15m length of cord is going to be great for general purpose rigging. Shorter lengths, say 5m, are good if you have a specific single-use purpose in mind such as a pickoff. Longer lengths may be useful for particular rigging jobs but can be messy.

Solution: Choose an appropriate length of cord usually 10-15m. If you have a one-off need for a longer jigger, clip two together end to end.

Making a jigger

As I mentioned at the start, this post is also about a jigger you make up yourself and not one you buy premade from the manufacturer. Don’t get me wrong I am a big fan of premade jigger systems for specific purposes, however, the reason I like to know how to build my own includes:

  • It can be less expensive than buying a premade.
  • You can have a custom length of cord.
  • You get to know how a jigger works and how it’s meant to go together.
  • When you find the jigger fairies have been and made a mess you know how to fix it.
  • By knowing the principles of building a jigger you can improvise if you need to during rescue or rigging.
  • You can easily replace parts if they need servicing during or after operations, e.g. the progress capture Prusik.

Download

I have put together a guide on how to put together a jigger. Just fill in your name and email and I will send you the download link.

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Top 5 Hacks for Rope Rescue

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