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Forums: BASE Jumping: General BASE:
Wind Effect vs FF Speed
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Oct 2, 2021, 12:58 AM
Post #1 of 4 (376 views)
Wind Effect vs FF Speed Can't Post

I jump a 420ft vertical cliff with a relatively clear landing area from which and I can always get a solid 2s to 3s freefall. I’ve jumped it around 75 times, always with no wind. If there is any wind, it is typically around 5 to 10 knots and I don’t jump, but now I'm thinking I can…

5 Knots = 5.753 mph
6 Knots = 6.904 mph
7 Knots = 8.805 mph
8 Knots = 9.206 mph
9 Knots = 10.357 mph
10 Knots = 11.508 mph

1s of freefall = 21.71 mph
2s of freefall = 42.04 mph
3s of freefall = 59.95 mph

It seems to me that if I take a 2s to 3s freefall my downward speed will overcome any wind forces that might cause off-headings.

Can anyone comment or advise please

(This post was edited by John_Scher on Oct 2, 2021, 6:07 AM)


Oct 2, 2021, 9:09 PM
Post #2 of 4 (330 views)
Re: [John_Scher] Wind Effect vs FF Speed [In reply to] Can't Post

I don't think anybody knows a scientific answer. We just know, from years of community experience and mishaps, that:

1. at zero or near-zero wind the "extra" risk is negligible
2. Beyond some level, the extra risk is suicidal
3. Somewhere in between 1 & 2, there is some unknown, dynamic amount of extra risk

Without quantitative predictive models, we have only ourselves as test dummies. So the question is how much extra (unknown) risk probability are you willing to accept, for the reward?

i.e., how fucking badly do you want to jump?

I suggest sticking with the conventional wisdom: to have zero or near-zero winds for slider down cliffs. Most of us have pushed that boundary a little bit, right? So we know that < 2-3 mph of crosswind is probably as good as you'll typically get, and maybe up to 5-6mph is OK once in a while if you're feeling good, and can get good separation, and you're feeling on your game, and, you have vents (which hopefully everybody does nowadays), someone cool is watching, etc etc etc.

And I think of risk as cumulative, so I consider the crosswind risk added up with all the other positive and negative factors of that object that day.

And there are also those who will jump in just about any condition, and they do fine... until they don't...

For me personally, it comes down to asking "what kind of jumper do I want to be?" I am patient and want to be safe and jumping when I'm an old man and not live a life of pain and disability, so I wait for good conditions, knowing I have walked away from a lot of jumps that would probably have worked out just fine. But I also absolutely respect people who want to jump their assess off, are highly skilled, and understand + accept the additional risk.


Oct 3, 2021, 6:22 AM
Post #3 of 4 (311 views)
Re: [Colm] Wind Effect vs FF Speed [In reply to] Can't Post

Spot on
For me it’s not worth the additional risk and like you said - you’ll get away with it until you don’t.


Oct 4, 2021, 10:17 AM
Post #4 of 4 (245 views)
Re: [John_Scher] Wind Effect vs FF Speed [In reply to] Can't Post

I have used this line of thought on rare occasion.
As ling as you get a solid 2-3 seconds and have decent separation, then most of the time you should be ok.
i guess it comes down to your acceptance that 'some of the time' you could experience a possible negative affect. in my mind though, that's BASE in general; I am certainly guilty of jumping in higher winds. when all other conditions listed above can be met.
I have never jumped a solid object with a headwind though..

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