Fall factor

[hakioawa]

While climbing some slab up in squamish this weekend, I had the opportunity to explain fall factor to a partner. Fall Factor (FF) = Length of Fall (LF) divided by Length of Rope).

 

So FF = LF/LR

 

The point of protection is to minimize FF. While leading out on a blank slab from the anchor, something occurred to me. Lets say the first piece is 30 from a bomber anchor. If I fall on a tight belay at the first piece I have a fall factor of ((30' + 30')/30') = 2. On the other hand if I have say 20 feet or slack I end up with a fall factor of ((30' + 50')/50' = 1.6.

 

So falling farther on a loose belay is better. Assuming of course I don't hit anything on the way down. Does this make sense?

[thelawgoddess]

rope stretch and other components of the entire system will also play a role in the fall factor, but yes - i believe that's why we're taught to belay leaders with some "slack" payed out ...

[Lambone]

Yeah, it more or less makes sense. But a fall factor of 1.6 is still pretty high. Instead of taking a 50 footer straigt onto the belay, put a piece in just above it. or at leats clip the most solid peiece in the anchor.

 

Check Petzls site for more info on this.

[allthumbs]

Are you shitting me? That makes no sense.

[Jim]

I think your calculations are off. If you fall on a tight belay (fall 3 feet with 30 ft of rope) your fall factor is 1.1. The greatest fall factor in most climbing situations is 2, unless you happen to be unlucky enough to climb above your belayer, don't put in a piece, and then fly past him. This would be a factor 2+ fall

[thelawgoddess]

i don't think they were recommending paying out 20 feet of slack at all times; just some numbers for examples' sakes. (i hope!!!) and you can NEVER have a fall factor over 2.

[hakioawa]

You can have a fall above 2. look at this guy.

 

If he falls he goes more than twice the length of his leash!

 

I've always given a leader slack, but it had more to do with not pulling him off.

[allthumbs]

I'm more interested in pucker factor.

[thelawgoddess]

i beg to differ ... but i'm hoping somebody else will do it for me 'cause i'm about to get off work.

 

ps - no via ferrata going on around here!

Edited December 5, 2002 by thelawgoddess

[genepires]

actually, it is possible to have a fall factor greater than 2. We have our not-so-smart leader way out there (30 feet) with no gear in. He/she falls and the eager belayer starts realing in the slack. Lets say the belayer bring in 9 feet of slack. Yeah it is alot but for this example lets just beleive this is true, OK?

Now look at the equation for fall factor. length fallen = 30+(30-9)=51 feet. length of rope out = 21 feet FF=51/21=2.43 There is your FF>2

[chriss]

 

 

This is not always true.

 

Example...(no or little slack)

Climbing along.

10ft above belay put in gear.

5ft above gear, fall.

 

10/15=.6666

 

Fell 10ft, double the distance above the pro.

Rope out, 15 ft, distance of climber to belay.

 

Example...(way you've been taught, say 5ft slack)

climbing along.

10ft above belay, put in gear.

5ft above gear, fall.

 

10+5/15+5=15/20=.75

 

Fell 15ft, 10ft and another 5ft in slack.

Rope out, 15ft and another 5ft slack.

 

Fall factors are different?!

Slack fall factor gets bigger with the more slack you add in!

The slack number adds to both the fall length and the rope out length. Decreasing the value of the rope distance to the pro that holds the fall.

 

Be careful, don't believe everything you read.

 

 

chris

[Yos]

The point of protection is to minimize FF.

 

Really? I would think rapid deceleration as a result of decking or hitting a ledge is more of a concern.

[texplorer]

Nice Observation Yos

. . . .but I thought protection was for in the tent?