Santa Barbara Tough Enough


Safety for Leg 2
March 16, 2020, 3:22 pm
Filed under: Uncategorized

Hi, runners. Trail types (including me) were excited by the change in Leg 2 to West Fork of Cold Spring. Right now that crossing is unsafe, ranging to deadly. Back of the envelope: one square foot exposure of water at 30 mph is about 44 cubic feet of water, or over 27 hundred pounds. That’s a ton of water pulling on each foot as you try to cross. The stream may subside; but even six inches is 1350 lbs of pull. Fast-moving water is indifferent to our well-being. We may have to revert to the old route. Updates as race day approaches.


4 Comments so far
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Hi – For newbies to Tough Enough, what is the “old route?”

Comment by Marc Leventhal

Embarrassing that I took that for granted. The route descriptions have been updated to include both road and trail, so there is now guidance for whichever is best on race day.

Comment by Hart K.

I think you have done F = ρvAg

I used F = C_d ρ v^2 A / 2 and with

ρ = 1000 kg/m^-3
C_d = 1 – 1.3 for human body
v = 14m/s
A = 0.025 m^2 (one leg in 30cm water)

you get

F = 2500N

or a quarter tonne per leg.

Comment by Martin Pattison

Your guess is right (about my approximation); I like your calc better than mine. Still plenty enough to take one’s feet and anything attached to them a long way down stream.

Comment by Hart K.




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