Figure-8 Block Testing Report 2021 V1.2

Figure-8 device block
testing report
VERSION 1.0, 2021
Figure-8 Device Block
Testing Report
Version 1.0 , 2021
Author: Grant Prattley
Over The Edge Rescue

https://overtheedgerescue.com
© 2021
For the latest version and for referencing purposes use:
Prattley, Grant. Figure-8 Device Block Testing Report.

Over the Edge Rescue. Version 1.0, 2021.
https://overtheedgerescue.com/canyoning/figure-8-device-block/
Canyoning: Figure-8 Device Block Testing Report 2021 (V1.0) Table of Contents 2
Table of Contents
Introduction............................................................................................... 4
What we set out to do.............................................................................. 5
Context..................................................................................................... 5
Variations tested....................................................................................... 9
Slow pull test results............................................................................... 13
Efficiency tests........................................................................................ 16
Practical use............................................................................................ 17
Conclusions............................................................................................. 19
References.............................................................................................. 20
Disclaimer............................................................................................... 20
Glossary of terms.................................................................................... 20
Appendix 1: Testing Kordas Dana 10mm............................................... 21
Appendix 2: Testing Kordas Dana 9mm................................................. 59
Introduction
Catching up with another canyoner recently, they showed me a failure method for a particular
Releasable Figure-8 Device Block used as a releasable set up for canyon abseiling.
Correct rigging Correct rigging Incorrect rigging

Releasable-8 Block Version 1 (V1)
This block is called Releasable-8 Block V1 (for reference purposes) – above left and middle. It’s
worth noting that rigged correctly and threaded through a small ring, rapide or chain, it works
well and does its intended job. You can use a carabiner on the small hole (minimum) – above left.
Alternatively, a quickdraw is attached to protect against accidentally abseiling on the wrong rope
until the final canyoner – above middle.
The problem is if you accidentally or incorrectly clipped the figure-8 block by the small ring of
the figure-8, with body weight, it would fail the Releasable-8 Block V1, and you would head
downwards quickly – above right.
This issue is a lack of understanding of the purpose of a figure-8 block. Once loaded, you need to
be able to release it. So the incorrect rigging loads the figure-8 block; you cannot drop a loop and
lower the load.
‘But this would never happen,’ I hear you saying.
The reason for this article and testing is there was a near miss. Someone rigged the Releasable-8
Block V1, incorrectly clipping the small hole directly into the anchor, and had a short free fall,
luckily into a deep pool.
Note: This article is about technical canyon rigging. It relates to specific canyoning techniques -
the Releasable-8 Block - that requires lots of practice to master and judgment to use in the right
place. This article does not constitute training of any sort.
What we set out to do
This near-miss prompted me to test various versions (and failure methods) of the figure-8 block
compared to other baseline methods.
• Releasable-8 block - normal loading

• Releasable-8 block forwards load small eye clipped - if you accidentally clipped the small eye
into the anchor, load the block during the abseil.
• Releasable-8 Block backwards load small eye clipped, e.g. when there is a quickdraw backup –
if you accidentally abseiled on the wrong rope, the one coming out of the bag.
• Figure-8 knot on a bight - as a baseline knot for the rope
• Munter Mule overhand - as a baseline for an alternative releasable system
• Biner block - as a baseline for a non-releasable block
Context
Releasable systems (contingency anchors)
It is essential to have a pre-rigged lowering set up to release the abseil line
in many canyoning situations.
Make sure you have enough rope left at the anchor to lower the person to
the bottom, i.e. at least the length of the pitch.
When the pitch is longer than half the rope, you need to join another and
set up for a big pitch. To have a releasable system, you need to either rig
on the topside of the bend or be prepared to pass a bend.
A releasable system is an active risk management tool used for:
• When the abseiler has jammed their descender, clothing or hair, the
system needs to be lowered – however, in other circumstances, such
as a foot entrapment or being stuck behind a waterfall, lowering the
abseiler could worsen the situation.
• While a canyoner is abseiling, managing sharp edges by lowering the
rope very slowly, ‘bleeding the rope’. This lowering spreads any wear
over a larger surface area. Re-setting the rope length between each
canyoner is needed.
• While the first canyoner is abseiling, set the length by lowering the
rope.
Releasable-8 block
The method uses a tied off figure-8 abseil device as a releasable block. It is
ideal for lower anchors as the block is directly on the anchor ring. Very little
re-rigging is needed for the last canyoner down. You need a spare (second)
figure-8 device on your harness.
Releasable-8 block
Munter mule overhand (Italian hitch tied off)
The Munter is a releasable abseil method tied off with a Mule and
finished with a carabiner or overhand knot. Ideally, the Munter mule
needs to be used on a higher anchor as the method takes more space
than the releasable-8 block.
Non-releasable systems
Non-releasable systems are fast and efficient methods to rig either
smaller dry pitches or for the last person down.
As these systems cannot be released, rescue is much more difficult. For

example, to lower someone from a biner block, you need to: apply a
small raising system or counterbalance, remove the block and transfer
the load to a lowering system.
Before using a non-releasable system, consider the pitch hazards and

the experience of the canyoners. Sharp edges are more difficult to
manage as the rope is fixed during an abseil. The two strands or stone
knot abseil is a suitable solution as it shares any wear over two ropes.
Biner block
A biner block is a fast and efficient method of rigging smaller dry
Munter Mule Overhand
pitches. This method is standard for the last canyoner (pitch leader) with
the Munter Mule. The biner block cannot be released, meaning rescue is
more complicated. Only deploy the rope you need out of the pack. Use
with caution on sharp edges due to the single fixed strand. Tie a clove
hitch on the carabiner’s spine on the opposite side to the abseil side.
Biner block
Methods and Materials
Methods
Slow pull tests
• As each test destroyed the rope, it was new for every test.
• Carabiners and rapides, where they were undamaged, were reused
for multiple tests.
• All knots and hitches had hand tension with all strands pulled tight.
• Each testing series records the slow pull tests set up (see Appendix
1-2).
• The slow pull testing was in one location.
– Aspiring Safety, 1/6 Burdale Street, Riccarton, Christchurch, New
Zealand.
– https://www.aspiring.co.nz/
• Vertical testbed 1.6m Electronic Universal Testing Machine, Model
WDW-50
– Maximum Test Force 50kN, sample rate 60 per second
– Jinan Chuanbai Instrument Equipment Co Ltd
Practical use testing

Practical use testing (lowering) occurred at Over the Edge Rescue, 55 Mckenzie Street, Geraldine,
New Zealand. https://overtheedgerescue.com
• 80kg test mass contained in a 70 litre PVC bags (Aspiring Safety) filled with four bags of 20kgs
of gravel. The test mass is secured into each bag so it can’t shift during testing.
Materials
Figure-8 device
Petzl Huit
• Manufactured by: Petzl (https://www.petzl.com/INT/en/

Professional/Descenders/HUIT)
• Material(s): aluminum
• Weight: 100 g
• Rope compatibility: 8 to 13 mm (single and half ropes)
• Working load limit: 100 kg
Korda’s Dana 10
• Manufactured by: Korda’s (https://www.sacidkordas.com/
en/producte/dana-10/)
• Type: Canyons rope semi-static A
• Diameter: 10 mm
• Weight: 68 g/m
• Breaking strength: 27.80 kN
• Static elongation: 2.7% (150kgs)
• Core proportion: 61%
• Sheath proportion: 39%
• Materials: Core/Sheath – Nylon/ Nylon
• Standards: EN 1891:1998, type A
Korda’s Dana 9
• Manufactured by: Korda’s (https://www.sacidkordas.com/
en/producte/dana-9/)
• Type: Canyons rope semi-static B
• Diameter: 9 mm
• Weight: 54 g/m
• Breaking strength: 22.20 kN
• Static elongation: 3.8% (150kgs)
• Core proportion: 58%
• Sheath proportion: 42%
• Materials: Core/Sheath – Nylon/Nylon
• Standards: EN 1891:1998, type B
Variations tested
Figure-8 on a bight knot Munter Mule Overhand
1. Figure 8 on a bight – 9 and 10mm rope. 1. Munter Mule Overhand – 9 and 10mm rope.
1 1
Biner Block Figure-8 Block V1
1. Clove hitch – 9 and 10mm rope. 1. Figure-8 Block V1 – 10mm rope.
2. Figure-8 Block V1 load forward small eye clipped – 10mm rope
1 1 2
Figure-8 Block V2
1. Figure-8 Block V2 through an 8mm rapide -10mm rope
1
Figure-8 Block V3
1. Figure-8 Block V3 through an 8mm rapide – 9 and 10mm rope
2. Figure-8 Block V3 load forward small eye clipped – 9 and 10mm rope
3. Figure-8 Block V3 load backward small eye clipped – 9 and 10mm rope
1 2 3
Figure-8 Block Mule Overhand (MO)
1. Figure-8 Block MO through an 8mm rapide – 9 and 10mm
2. Figure-8 Block MO load forward small eye clipped – 9 and 10mm rope
3. Figure-8 Block MO load backward small eye clipped – 9 and 10mm rope
1 2 3
How to tie the releasable-8 block versions
Version 11
Version 22
X formed
here
Version 33
two
opposing
loops
1 Originally from Commission Internationale de Canyon (CIC)

2 Manuel Professional De Canyonisme, 2018, Page 142. CREPS
3 Canyoning Technical Manual, 2021, Page 138. Over the Edge Rescue
Mule overhand4
4 Canyoneer LVL3 Manual, 2017, Page 106. ICOPRO.
Slow pull test results
Kordas Dana 10mm Semi-static rope
Slow pull tests (100mm/minute)
Avg. #
Items tested % Comment Appx. 1
kN Tests
Figure-8 on a bight knot 19.53 70 5 Broke at the knot pg. 22
Munter mule overhand 15.35 55 3 Broke at the 12mm carabiner pg. 25
Biner block 16.31 59 3 Broke at the 8mm rapide pg. 28
Figure-8 device block V1 16.17 58 3 Broke at the 8mm rapide pg. 31
Figure-8 device block V1 forward 1.29 5 3 First Slip 0.88kN, kept on pg. 34
load small eye clipped slipping
Figure-8 device block V2 3.56 13 3 First slip 3.08kN, kept on pg. 37

slipping
Figure-8 device block V3 16.12 58 3 Broke at the 8mm rapide pg. 40
Figure-8 device block V3 forward 3.95 14 3 First slip 2.43kN, kept on pg. 43
load small eye clipped slipping
Figure-8 device block V3 22.64 81 3 Broke at the Figure-8 device pg. 46

backwards load small eye clipped
Figure-8 device block mule 16.58 60 3 First slip 10.13kN, MO pg. 49

overhand (MO) unwound from the Fig-8 360
degrees. Broke at the 8mm
rapide
Figure-8 device MO forward load 19.07 69 3 First slip 4.59kN, MO unwound pg. 52
small eye clipped from the Fig-8 720 degrees.
Broke at one side of the fig-8
device
Figure-8 device block MO 7.70 28 3 First slip 7.44kN, kept on pg. 55

backwards load small eye clipped slipping, the overhand bight
started to get pulled through
and get smaller
Thumb and finger One hand Two hands
Figure-8 device friction lowering 0.75 1.15 2.39 pg. 58

mode through 8mm rapide
Kordas Dana 9mm Semi-static rope
Slow pull tests (100mm/minute)
Avg.
Items tested % # Tests Comment Appx. 1
kN
Figure-8 on a bight knot 15.95 72 5 Broke at the knot pg. 60
Munter mule overhand 12.98 58 3 Broke at the 12mm carabiner pg. 63
Biner block 13.82 59 3 Broke at the 8mm rapide pg. 66
Figure-8 device block V3 7.59 35 3 Kept on slipping pg. 69
Figure-8 device block V3 2.98 13 3 Kept on slipping pg. 72

forward load small eye clipped
Figure-8 device block V3 19.08 86 3 Broke at the rope clamp (1), and pg. 75
backwards load small eye figure-8 device (2)
clipped
Figure-8 device block MO 13.20 59 3 First slip 5.14kN, MO unwound pg. 78

from the Fig-8 360 degrees. Broke
at the 8mm rapide
Figure-8 device MO forward 16.87 76 3 First slip 2.06kN, MO unwound pg. 81

load small eye clipped from the Fig-8 720 degrees. Broke
at one side of the fig-8 device
Figure-8 device block MO 7.12 32 3 First slip 5.92kN, kept on slipping, pg. 84
backwards load small eye the overhand bight started to get
clipped pulled through and get smaller
Thumb and finger One hand Two hands
Figure-8 device friction 0.79 1.25 2.02 pg. 87

lowering mode through 8mm
rapide
Analysis of slow pull testing
All the blocks/releasable systems should be the same when tested through the 8mm rapide or
on a carabiner. Ideally, this is 15kN (or more) rope strength for 10mm and 13kN for 9mm rope or
assessed to have a sufficient margin when it does not meet these numbers and slips.
When the figure-8 block is misused (for the forwards or backwards loading on the small eye), it
should not fail dramatically and if it does slip, be at least 2kN or more.
Control Variations - 9 and 10mm

All the control variations tested, including the Figure-8 on a bight knot, Munter Mule Overhand,
and biner block broke on average a minimum of 13kN for 9mm and 15kN for 10mm rope
strength.
• The recommendation is all control variations are suitable for canyoning
Figure-8 Block V1 - 10mm

While the figure-8 Block V1 threaded through an 8mm rapide broke on average above 16kN,
when loaded forward with the small eye clipped, however, it failed suddenly at around 1kN. This
failure method demonstrates the near miss that occurred in the canyon.
• Recommendation: not suitable for canyoning

The figure-8 Block V2 threaded through an 8mm rapide kept slipping on average at 3.5kN.
This was assessed as not having sufficient margin for a figure-8 block when compared to other
methods.
• The recommendation is the V2 is not suitable for canyoning.

The figure-8 block V3, through an 8mm rapide, broke and loaded backwards small eye clipped on
average was a minimum of 16kN rope strength.
The figure-8 block V3 loaded forward small eye clipped kept slipping on average at 4kN.
• The recommendation is the V3 is suitable for canyoning.

The figure-8 block V3 threaded through an 8mm rapide kept slipping on average at 7kN. This was
assessed as having sufficient margin for a figure-8 block.
The figure-8 block V3 loaded forward small eye clipped kept slipping on average at 4kN.
The figure-8 block V3 loaded backwards small eye clipped broke on average was a minimum of
19kN rope strength.
• The recommendation is the V3 is suitable for canyoning.
Figure-8 Block Mule Overhand - 10mm
The figure-8 block mule overhand threaded through an 8mm rapide broke and loaded forward
small eye clipped at a minimum of 16kN rope strength.
The figure-8 block mule overhand loaded backwards small eye clipped, kept on slipping, the
overhand bight started to get pulled through and get smaller, on average at 7kN.
• The recommendation is the mule overhand is suitable for canyoning.
Figure-8 Block Mule Overhand - 9mm

The figure-8 block mule overhand threaded through an 8mm rapide broke and loaded forward
small eye clipped was a minimum of 13kN rope strength.
The figure-8 block mule overhand loaded backwards small eye clipped, kept on slipping, the
overhand bight started to get pulled through and get smaller, on average at 7kN.
• The recommendation is the mule overhand is suitable for canyoning.
Efficiency tests
Now that we have established the figure-8 block V3 and figure-8 block mule overhand are
suitable, we compared and contrasted how easy they are to use in reality. To make this relevant, I
have compared this to tying Munter Mule Overhand and biner block
Initially tie – covert to lower – reinstate to tied off – convert to retrieve

• The gear taken from the harness is in time when initially tying
• Fig-8 blocks completed with a quick draw backup with carabiners closed
• The tying method is correctly DRESSED when finished
• Lowering setup rope charged with 5kg
• Time is the average of 3 attempts in seconds
• Each attempt is made smoothly at NORMAL speed if well-practiced
(Note: I didn’t set out to undertake the method as quickly as possible. I undertook a smooth
speed that was not rushed (NORMAL) with a high-quality result (DRESSED), so I could
consistently compare methods.)
• Done on flat ground with an anchor at head height with 9mm rope
Type tested Time to tie Time to Time to Time to convert to retrieve

initially (sec) convert to reinstate to (sec)
lower (sec) tied off (sec)
Figure-8 device block V3 19 10 14 5 (quick draw)
Figure-8 device block MO 33 9 26 6 (quick draw)
Munter mule overhand 23 9 12 25 (biner block)
16 (biner block preloaded5)
13 (to double rope)
Analysis of the efficiency tests

When you consider time to tie initially, convert to lower, reinstate to tied off and convert to
retrieve, there was very little in it. Not enough to argue one way or the other.
5. When you don’t need to bleed (slowly lower) the rope for sharp edge management, the biner block can
be preloaded onto the standing part of the rope close to the ring as the last abseiler is descending.
Practical use
Convert to lower – lower the load – reinstate to tied off
• Figure-8 block versions (V3 and MO) and Munter Mule Overhand (MMO) were tied in both
9mm and 10mm rope.
• An 80kg load was lowered onto the Figure-8 blocks and MMO.
• The anchor was a free hanging 8mm oval rapide.
• The Figure-8 blocks and MMO untied and lowered then retied a minimum of 2 times over a
10m lower.
Type tested Rope size Comments

Figure-8 device 10mm – The block was easily untied, lowered and retied.
block V3 – The rope was easy to hold with one hand.
– There was noticeable twisting in the rope during lowering.
9mm – The block was easily untied, lowered and retied.
– The rope was easy to hold with one hand.
Figure-8 device 10mm – The block was easily untied, lowered and retied.
block MO – The rope was easy to hold with one hand.
– The overhand had to be retied below the mule.
– The overhand took time, and it was challenging to get dressed.
9mm – Initially not easy to untie and lower the load. The second and third
tries were easier as the overhand was below the mule.
– Difficult to retie with the smaller diameter rope.
– The overhand took time, and it was challenging to get dressed.
Munter mule 10mm – The Munter was easily untied, lowered and retied.
overhand – The rope was easy to hold with one hand.
– There was no noticeable twisting in the rope during lowering.
9mm – The Munter was easily untied, lowered and retied.
– The rope was easy to hold with one hand.
– There was no noticeable twisting in the rope during lowering.
Analysis of conversion testing

Figure-8 device block V3: Was easy to untie, lower and retie. However, had to unclip the
quickdraw to drop a loop and then reclip before lowering. Also twisted the rope when lowered.
Figure-8 device block MO: Was easy to untie, lower and retie in 10mm, didn’t have to unclip the
quickdraw. However more challenging to retie in 9mm due to less friction around the figure-8
device. Also twisted the rope when lowered. Recommend to tie the overhand below the mule
which is different to that shown in the reference material6.
Munter mule overhand: Was easy to untie, lower and retie and didn’t twist the rope.
6. Canyoneer LVL3 Manual, 2017, Page 106. ICOPRO.
Retrieval
Our thoughts and practical experience observations of using these methods when retrieving the
rope.
Figure-8 device block V3:

• Has lower profile for pulling over obstacles.
• Easy to untie once retrieved.
Figure-8 device block MO:

• It is not as low profile for pulling over obstacles due to the mule overhand left in place.
• Easy to untie once retrieved.
Biner block:
• Has lower profile for pulling over obstacles.
• The biner block (clove hitch on a carabiner) can be challenging to loosen and untie once
retrieved.
Conclusions
Figure-8 device blocks
From a slow pull testing point of view, only two figure-8 blocks performed to a satisfactory level:
Figure-8 block V3 and Figure-8 mule overhand (MO).
retrieve, there was very little in it. Not enough to argue one way or the other.
When you convert to lower, lower the load and retie when loaded; both blocks performed well in
10mm rope. However, the mule overhand version in 9mm was more challenging to reinstate to
tied off while this was easy in the V3. Also, there was noticeable twisting observed when lowering.
Considering all the things we have learned, we recommend both the V3 and MO figure-8 device
blocks for 9mm and 10mm ropes.
Munter mule overhand and biner block

From a slow pull testing point of view, the Munter Mule Overhand (MMO) and biner block
performed to a satisfactory level.
retrieve, there was very little in it compared to the figure-8 blocks. Not enough to argue one way
or the other.
When you convert to lower, lower the load and retie when loaded, the MMO performed well in
both 9 and 10mm ropes. Also, there was no noticeable twisting observed when lowering.
Considering all the things we have learned, we recommend the MMO and biner block for 9mm
and 10mm ropes.
Final thoughts
We set out to test various versions (and failure methods) of the figure-8 block compared to other
baseline methods. We went quite a long way down the rabbit hole, but out the end came an
understanding of the tools we use and how they perform.
There are many canyoners using the Figure-8 device block as they find it easier to tie, and it’s
quick to transition from abseil to retrieval modes.
The Munter Mule Overhand (MMO) is ideal for situations where you need to lower and then reset
the rope. For aquatic canyons, especially with sharp edges, this is our go-to method. The MMO
easily converts to a biner block and is less likely to get stuck on retrieval. Also, from time to time,
for the last person down, we use double rope for sharp edge management or tricky retrievals
where we want a clean rope. Converting the MMO to a double rope is straightforward.
In the end, both the figure-8 device block and MMO/biner block are tools in the toolkit to
manage risk in the canyon environment. Using both methods and applying them in appropriate
places is the recommended approach.
References
1. Petzl. https://www.petzl.com/
2. Korda’s. https://www.sacidkordas.com/
3. Canyoning Technical Manual. 2021. Over the Edge Rescue
4. Manuel Professional De Canyonisme. 2018. CREPS.
5. Canyoneer LVL3 Manual. 2017. ICOPRO.
Disclaimer
1. Information contained in this test report is not an instructional guide—intended to supplement
training from experienced and competent canyoning instructors.
2. Use at your own risk. The publisher and author assume no responsibility or liability for any
accident, injury, loss or damage sustained while following any of the recommendations or
techniques described.
3. The publisher and author assume no responsibility or liability for any errors or omissions in the
content of this report. The information contained in this report is provided on an “as is” basis
with no guarantees of completeness, accuracy, usefulness or timeliness.
4. Testing was under controlled conditions with a limited set of equipment. Testing with different
equipment or operating in different conditions may result in different outcomes.
5. The views, information, or opinions expressed in the test report are solely those of the author
and do not necessarily represent those of other organisations or individuals listed.
Glossary of terms
Bends: Where two pieces of rope or webbing are tied together usually at their ends, with both
playing an integral part. The load is pulling in line through the bend. An example is a double
fisherman’s bend.
Maximum Force (kN): Maximum amount of tensile stress that the material can withstand before
failure (rupture), such as breaking or permanent deformation. Tensile strength specifies the point
when a material goes from elastic to plastic deformation.
Force (kN): In physics, force is the push or pull on an object with mass that causes it to change
velocity (to accelerate). Force represents as a vector, which means it has both magnitude and
direction. The SI unit of force is the newton (N).
Knots: ‘If it’s not a bend or a hitch then it’s a knot’. In the widest sense a generic name for all
types of rope and cord entanglements but specifically where a connection is tied that is self-
sustaining in rope or webbing.
Hitches: Where a rope is tied to an object where if the object is removed the hitch falls apart. An
example is the Italian/Munter hitch.
Appendix 1: Testing Kordas Dana 10mm

Figure-8 on a bight 10mm
Materials
Ropes – Korda’s 10mm Dana (27.8kN)
Test setup
Knots – Figure-8 on a bight
Test parameters
Speed – Slow pull 100mm/minute
Tested between – Rope clamp and 12mm pin
Results
Date # Breaking % Comments
force (kN)
5/06/20 19 19.87 71 Broke inside knot
5/06/20 20 19.54 70
5/06/20 21 19.28 69
5/06/20 22 20.15 72
5/06/20 23 18.82 68
Average 19.53 70
* Sample 5/06/20 #19 shown on the following pages.
Test Date: Friday, 5 June 2020

Max Force (kN): 19.87
Product Name: Fig-8 oab
Batch #: 19
Material: Kordas Dana 10mm
Force-Time Curve
Graph Area
Force(kN)
Tested by: Grant Prattley
Signed:
Machine has a current calibration certificate. www.aspiring.co.nz
Munter mule overhand 10mm

Materials
Rope – Korda’s 10mm Dana (27.8kN)
Hardware – CT Snappy steel screwlock carabiner (40kN)
Test setup
Hitches – Munter mule overhand on steel carabiner
Test parameters
Tested between – 12mm pins
Results
Date # Max % Comments
force
(kN)
31/10/19 12* 15.51 56 Broke at the rope at the first cross
of the Munter
31/10/19 13 15.87 57
18/06/19 11 14.67 53
Average 15.35 55
Test Date: Thursday, 31 October 2019
Product Name: Munter Mule Overhand
Batch #: 12
Material: 10mm Kordas Dana
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:
Biner block 10mm

Materials
Hardware – CT Large steel screwlock carabiner (50kN)

– Maillon rapide 8mm steel oval (35kN)
Test setup
Hitches – Clove hitch on spine of steel carabiner
Attachments – Threaded through rapide and clamped
Test parameters
Results
force
(kN)
11/03/21 2* 15.21 55 Broke at the 8mm rapide
31/03/21 3 16.91 61
31/03/21 4 16.80 60
Average 16.31 59
Test Date: Thursday, 11 March 2021

Product Name: Biner Block
Batch #: 2
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:
Figure-8 device block 10mm (V1)

Materials
Hardware – Petzl Huit Figure-8

Test setup
Fig-8 blocks – Version 1 on a figure-8 device
Attachments – Clamped leg threaded through rapide
Test parameters
Results
force
(kN)
24/10/19 15 16.13 58 Broke at the 8mm rapide
24/10/19 16 16.08 58
11/03/21 4* 16.31 59
Average 16.17 58
Test Date: Thursday, 11 March 2021

Product Name: Figure-8 Device Block V1
Batch #: 4
Material: 10mm Dana Kordas
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:
Figure-8 device block 10mm (V1 load forwards)

Materials

– Petzl Huit Figure-8
Test setup
Attachments – Small eye clipped to steel carabiner

– Clamped leg load forwards
Test parameters
Results
Date # First Max % Comments
slip force
(kN) (kN)
17/09/21 10* 0.76 1.37 5% Kept on slipping
17/09/21 11 0.81 1.41 5%
17/09/21 12 1.08 1.09 4%
Average 0.88 1.29 5%
Test Date: Friday, 17 September 2021

Product Name: Fig-8 block V1 forwards loading small eye clipped
Batch #: 10
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:

Materials

Test setup
Test parameters
Results
slip force
(kN) (kN)
17/09/21 1* 3.01 3.99 14 Kept slipping
17/09/21 2 2.60 2.94 11
17/09/21 3 3.62 3.75 13
Average 3.08 3.56 13

Product Name: Figure-8 block Version 2
Batch #: 1
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:

Materials
Hardware – CT D-Shaped steel screwlock carabiner (50kN)

Test setup
Test parameters
Results
force
(kN)
31/03/21 6 16.41 59
31/03/21 7 16.52 59
Average 16.12 58
Test Date: Wednesday, 31 March 2021

Product Name: Fig-8 Block v3
Batch #: 5
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:

Materials

Test setup

Test parameters
Results
slip force
(kN) (kN)
17/09/21 4* 2.69 4.91 18 Kept slipping
17/09/21 5 2.08 3.09 11
17/09/21 6 2.52 3.86 14
Average 2.43 3.95 14

Product Name: Fig-8 block V3 forward loading small eye clipped
Batch #: 4
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:
Figure-8 device block 10mm (V3 load backwards)

Materials

Test setup

– Clamped leg load backwards
Test parameters
Results
force
(kN)
17/09/21 7* 23.06 83 Broke at the figure-8 block
17/09/21 8 22.84 82
17/09/21 9 22.01 79
Average 22.64 81

Product Name: Fig-8 block V3 backwards loading small eye clipped
Batch #: 7
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:
Figure-8 device block 10mm (MO)

Materials

Test setup
Fig-8 blocks – Mule overhand on a figure-8 device
Test parameters
Results
slip force
(kN) (kN)
15/11/21 1* 11.34 16.54 59 Mule Overhand unwound
from the Fig-8 360 degrees.
15/11/21 2 8.63 17.62 63
Broke at the 8mm rapide.
15/11/21 3 10.43 15.57 56
Average 10.13 16.58 60
Test Date: Tuesday, 16 November 2021

Product Name: Fig 8 Block mule overhand
Batch #: 1
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:
Figure-8 device block 10mm (MO load forwards)

Materials

Test setup

Test parameters
– 12mm pins
Results
slip force
(kN) (kN)
15/11/21 4 4.22 18.21 66 MO unwound from the
Fig-8 720 degrees. Broke
15/11/21 5* 4.47 19.91 72
on one side of the figure-8
15/11/21 6 5.07 19.1 69 device.
Average 4.59 19.07 69
Test Date: Wednesday, 17 November 2021

Product Name: Fig 8 Block mule overhand forwards load
Batch #: 5
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:
Figure-8 device block 10mm (MO load backwards)

Materials

Test setup

Test parameters
– 12mm pins
Results
slip force
(kN) (kN)
15/11/21 7* 8.12 8.59 31 Kept slipping, the overhand
bight started to get pulled
15/11/21 8 6.19 6.19 22
through and get smaller.
15/11/21 9 8.01 8.31 30
Average 7.44 7.70 28
Test Date: Tuesday, 16 November 2021

Product Name: Fig 8 Block mule overhand backwards small eye clipped
Batch #: 7
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:
Figure-8 device block 10mm (friction)

Materials

Test setup
Fig-8 blocks – Set up in lowering mode against rapide
Test parameters
Results
Date # Thumb & 1 hand (kN) 2 hands (kN)
finger (kN)
10/12/21 23* 0.75 1.15 2.39
Test Date: Friday, 10 December 2021

Product Name: Fig-8 block friction
Batch #: 23
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:

Figure-8 on a bight 9mm
Materials
Test setup
Test parameters
Results
Date # Max force % Comments
(kN)
5/06/20 14* 16.35 74 Broke inside knot
5/06/20 15 15.30 69
5/06/20 16 15.92 72
5/06/20 17 16.05 72
5/06/20 18 16.15 73
Average 15.95 72
Test Date: Friday, 5 June 2020

Product Name: Fig-8 oab
Batch #: 14
Force-Time Curve
Graph Area
Force(kN)
Signed:
Munter mule overhand 9mm

Materials
Test setup
Hitches – Munter mule overhand on steel carabiner
Test parameters
Results
force
(kN)
24/09/21 13* 12.97 58 Broke at the first cross of the
Munter
24/09/21 14 13.48 61
24/09/21 15 12.49 56
Average 12.98 58

Product Name: Munter muler overhand
Batch #: 13
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:
Biner block 9mm

Materials

Test setup
Hitches – Clove hitch on spine of steel carabiner
Test parameters
Results
force
(kN)
24/09/21 2 13.65 61
24/09/21 3 12.41 56
Average 13.82 59

Product Name: Biner block
Batch #: 1
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:

Materials

Test setup
Test parameters
Results
(kN)
24/09/21 4* 7.80 35 Kept slipping
24/09/21 5 8.15 37
24/09/21 6 6.83 31
Average 7.59 35

Max Force (kN): 7.8
Product Name: Fig-8 block v3
Batch #: 4
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:

Materials

Test setup

Test parameters
Results
(kN)
24/09/21 7* 3.01 14 Kept slipping
24/09/21 8 3.42 15
24/09/21 9 2.51 11
Average 2.98 13

Product Name: Fig-8 block v3 load foward small eye
Batch #: 7
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:
Figure-8 device block 9mm (V3 load backwards)

Materials

Test setup

Test parameters
Results
force
(kN)
24/09/21 10* 19.89 90 Broke at the rope grab
24/09/21 11 18.59 84 Broke at the figure-8 block
24/09/21 12 18.76 85
Average 19.08 86

Product Name: Fig-8 block v3 load backwards small eye
Batch #: 10
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:
Figure-8 device block 9mm (MO)

Materials

Test setup
Test parameters
Results
slip force
(kN) (kN)
24/11/21 1* 5.53 13.00 59 MO unwound from the Fig-
8 360 degrees. Broke at the
24/11/21 2 4.98 12.91 58
8mm rapide.
24/11/21 3 4.92 13.69 62
Average 5.14 13.20 59

Product Name: Fig-8 Block MO
Batch #: 1
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:
Figure-8 device block 9mm (MO load forwards)

Materials

Test setup

Test parameters

– 12mm pins
Results
slip force
(kN) (kN)
24/11/21 4* 2.48 17.30 78 MO unwound from the Fig-
8 720 degrees. Broke at one
24/11/21 5 1.60 17.31 78
side of the figure-8 device.
24/11/21 6 2.10 16.01 72
Average 2.06 16.87 76

Product Name: Fig-8 Block MO foward load small eye clipped
Batch #: 4
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:
Figure-8 device block 9mm (MO load backwards)

Materials

Test setup

Test parameters
Results
slip force
(kN) (kN)
10/12/21 1* 5.85 7.24 33 Kept slipping, the overhand
bight started to get pulled
10/12/21 2 5.83 7.18 32
through and get smaller.
10/12/21 3 6.09 6.95 31
Average 5.92 7.12 32

Product Name: Fig-8 Block MO backward load small eye clipped
Batch #: 1
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:

Figure-8 device block 9mm (friction)

Materials

Test setup
Fig-8 blocks – Set up in lowering mode against rapide
Test parameters
Results
Date # Thumb & 1 hand (kN) 2 hands (kN)
finger (kN)
10/12/21 22* 0.79 1.25 2.02

Product Name: Fig-8 block friction
Batch #: 22
Force-Time Curve
Graph Area
Force(kN)
Time(s)
Signed:


Figure-8 Block Testing Report 2021 V1.2

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Figure-8 device block

Author: Grant Prattley

Over The Edge Rescue

For the latest version and for referencing purposes use:

Prattley, Grant. Figure-8 Device Block Testing Report.

Correct rigging Correct rigging Incorrect rigging

‘But this would never happen,’ I hear you saying.

• Releasable-8 block - normal loading

A releasable system is an active risk management tool used for:

As these systems cannot be released, rescue is much more difficult. For

Before using a non-releasable system, consider the pitch hazards and

Practical use testing

• Manufactured by: Petzl (https://www.petzl.com/INT/en/

1 Originally from Commission Internationale de Canyon (CIC)

4 Canyoneer LVL3 Manual, 2017, Page 106. ICOPRO.

Munter mule overhand 15.35 55 3 Broke at the 12mm carabiner pg. 25

Biner block 16.31 59 3 Broke at the 8mm rapide pg. 28

Figure-8 device block V1 16.17 58 3 Broke at the 8mm rapide pg. 31

Figure-8 device block V2 3.56 13 3 First slip 3.08kN, kept on pg. 37

Figure-8 device block V3 16.12 58 3 Broke at the 8mm rapide pg. 40

Figure-8 device block V3 22.64 81 3 Broke at the Figure-8 device pg. 46

Figure-8 device block mule 16.58 60 3 First slip 10.13kN, MO pg. 49

Figure-8 device block MO 7.70 28 3 First slip 7.44kN, kept on pg. 55

Thumb and finger One hand Two hands

Figure-8 device friction lowering 0.75 1.15 2.39 pg. 58

Munter mule overhand 12.98 58 3 Broke at the 12mm carabiner pg. 63

Biner block 13.82 59 3 Broke at the 8mm rapide pg. 66

Figure-8 device block V3 7.59 35 3 Kept on slipping pg. 69

Figure-8 device block V3 2.98 13 3 Kept on slipping pg. 72

Figure-8 device block MO 13.20 59 3 First slip 5.14kN, MO unwound pg. 78

Figure-8 device MO forward 16.87 76 3 First slip 2.06kN, MO unwound pg. 81

Thumb and finger One hand Two hands

Figure-8 device friction 0.79 1.25 2.02 pg. 87

Control Variations - 9 and 10mm

• The recommendation is all control variations are suitable for canyoning

Figure-8 Block V1 - 10mm

• Recommendation: not suitable for canyoning

Figure-8 Block V2 - 10mm

• The recommendation is the V2 is not suitable for canyoning.

Figure-8 Block V3 - 10mm

• The recommendation is the V3 is suitable for canyoning.

Figure-8 Block V3 - 9mm

• The recommendation is the V3 is suitable for canyoning.

• The recommendation is the mule overhand is suitable for canyoning.

Figure-8 Block Mule Overhand - 9mm

• The recommendation is the mule overhand is suitable for canyoning.

Initially tie – covert to lower – reinstate to tied off – convert to retrieve

Type tested Time to tie Time to Time to Time to convert to retrieve

Analysis of the efficiency tests

Type tested Rope size Comments

Analysis of conversion testing

6. Canyoneer LVL3 Manual, 2017, Page 106. ICOPRO.

Figure-8 device block V3:

Figure-8 device block MO:

Munter mule overhand and biner block

Appendix 1: Testing Kordas Dana 10mm

Tested between – Rope clamp and 12mm pin

Test Date: Friday, 5 June 2020

Tested by: Grant Prattley

Machine has a current calibration certificate. www.aspiring.co.nz