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What Happens in a Fall? Falling climber builds up momentum (force x time) When climber is ‘stopped’ (either by rope/anchor system or by hard

deck) the resulting forces needs to be absorbed Climbing rope (dynamic) acts like a SPRING and ideally absorbs most

of this force (the maximum amount NOT absorbed by the rope is the rope’s IMPACT FORCE rating)

“Fall-factor” (larger numbers are worse) indicates SEVERITY of fall and is related to the ability of the rope to act as a good spring and

absorb fall force (less rope equals less good spring) The remaining force (impact force) is absorbed by the ANCHOR and

THE CLIMBER Actually, the anchor needs absorbs 1.7x to 2x of the impact force

WITHOUT BREAKING (extra .7x to 1x due to the belayer force counter balancing the climber and stopping the fall)

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FALL FACTOR = Height of fall Total Length of rope out (ie. amount rope acting spring)

Fall Factor

80’

80’

80’ Rope Slack in System Fall

5’ 80’

Fall Factor = = 0.06255

80

KEY: Climber

Anchor

Rope

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approx force on anchor:

3-4KN

5’80’

factor 0.0625

rope out:

fall:

20’

40’

factor 0.5

approx force on anchor:

8-10KN

rope out:

fall:

20’ 20’

factor 1

approx force on anchor:

12-15KN

rope out: fall:

10’

20’

factor 2

approx force on anchor:

16-20KN

rope out:

fall:

KEY: Climber

Anchor

Rope

Pro

Fall Factor:Examples

LEAD FALLS SLINGSHOT TOP ROPE FALLS

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Anchor Forces

Anchor (naturals, gear, runners, webbing, ‘biners etc… ) needs to absorb 1.7x to 2x of the impact force Ideally, anchor should be built to withstand 30KN of force (approx 1.5x worst case lead fall)

KEY: Climber

Anchor

RopeZero Motion (stopped): Belayer force EQUALS Climber force Anchor subjected to BOTH forces

Force from climber

Force from belayer

Force on anchor is SUM of both

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Doubling fall factor results in approximately 1.4x increase in impact force

Ropes are rated for impact force from a 80kG climber and factor-of-1.77 fall Runners and anchor need to absorb 1.7x-2x impact force of fall Lead falls generate significantly more impact force than slingshot top rope falls

More info: www.climbtennessee.com/train/fall.html www.bealropes.com/english.dir/forces.html

Anchor Forces:Details

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Forces (approx)

1KN = 220lb (ie. 1 person static) approx 1G 10KN = 2200lbs (max from rope) approx 10G’s 12KN = 2640lbs (ie. Injury/Death) approx 12G’s 15KN = 3300lbs 25KN = 5500lbs

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1m = 3 feet = 4m/s = 10mph 3m = 10 feet = 8m/s = 17mph 6m = 20 feet = 11m/s = 24mph 10m = 33 feet = 14m/s = 31mph 20m = 66 feet = 20m/s = 44mph

Speeds from falls (approx)

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1m = 980J = 4m/s = 10mph 3m = 2940J = 8m/s = 17mph 6m = 5880J = 11m/s = 24mph 10m = 9800J = 14m/s = 31mph 20m = 19600J = 20m/s = 44mph

Energy from falls (approx)mgh & ½ mv2

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2” Webbing 30kN ($0.55/ft) 1” Webbing 18kN ($0.30/ft) 9/16” Webbing 7-11kN ($0.22/ft) 5mm Spectra 20kN ($1.05/ft) 4mm cord 3kN ($0.20/ft) 5mm cord 5kN ($0.25/ft) 6mm cord 8kN ($0.35/ft) 7mm cord 11kN ($0.40/ft) 8mm cord 11kN ($0.50/ft) Nylon runner 22kN ($2.0/ft – 0.75’, 2’, 4’ ) Spectra runner 27kN ($3.5/ft – 0.5’, 2’, 3’, 4’

)

Dynamic Rope (impact force) 7kN-10kN ($0.60/ft (approx): 165’, 200’, 230’)

Strength of Webbing

Gear Strength Cost

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‘biner 18-25kN / 6-9kN (gate open) #1 Nut 4.3/ 9.1mm 2kN #5 Nut 8.4/13.5mm 6kN #6 Nut 10.2/15.5mm 10kN

#1 Hex 10.7/15.5mm 6kN #3 Hex 13.9/20.1mm 10kN

0.5 Tricam 16/28mm 10kN 2 Tricam 28.5/41mm 15kN 2.5 Tricam 32/47.5mm 18kN

0.1 BD Cam 9.9-17mm 7kN 0.2 BD Cam 10.2-16.2mm 8kN 0.3 BD Cam 12.5-21.5mm 10kN 0.75 BD Cam 24-39.5mm 16kN

Strength of Gear

Gear Useful Dimensions Strength