) or head equal to two hands 
Yes Macroscien, it is paradoxical. But you've checked the equation haven't you? You're always up for an equation check. It's just the standard drag on a bluff body equation. I've checked it a few times because the number seemed so high. Maybe I'd missed a factor of 10? Can't find it. And of course it has been applied to breaking a water surface rather than at steady speed fully immersed, but the two situations would have to be comparable.
But, if hydrodynamical forces are any less, how do you explain barefoot water skiing? The forces on a 10 metre diver are all halved at the lower speed, but still?
) or head equal to two hands
Just found this research on ground reaction forces on gymnasts. Peaks at over 30 newtons per kg of body mass. Which is about 150kg peak force for a 50kg gymnast rolling and tumbling across the floor.
from www.ncbi.nlm.nih.gov/pmc/articles/PMC314389/
The rough calculations gave unexpectedly high forces, but maybe we just underestimate the peak forces that athletes shrug off without injury.
Don't think we've discredited the injured sailor's assessment that the water did it.
I don't know 172 feet = 52 metres must be getting close. Dana Kunze has his ankles taped , his knees taped, 4 pairs of budgies and zinc cream on his nose. If you get to the end you'll see the tape gets shredded.
(Using the old "v squared = 2as" equation we see he hits the water at 62 knots. That assumes a vacuum, but air resistance probably hasn't kicked in to reduce that by much.)
I am afraid of heights 
I am afraid of heights
(jump from 10 meters )
+1 what Mat said.
If there is little or no movement, or erratic movement, get there QUICK!
If someone is badly injured they probably won't be able to give ANY signal!
Any time you witness a crash, watch and monitor. If possible get there ASAP. If all is good, nothing lost. If not, seconds may count!
For some one sailing past and checking up on you, thumbs up (especially with eye contact) gets the message across that you are OK, but if you think you see this signal, always double check your first impression to make sure you got it right.
Had to look up non-newtonian fluids, water wasn't listed. But it looks like a non-newtonian fluid just means the shear force is not linearly proportional to the rate of distortion. ie. the 2nd term on the right hand side of the Navier Stokes Equation doesn't work as it should.
(This equation looks complicated but is just F=ma for fluids. The ugly looking left hand side of the equation just allows the mathematics to follow a particular fluid particle. The first term on the right is just the pressure force on the fluid particle of interest, the last is external forces on the particle of fluid we're following, usually gravity.
That 2nd derivative of the velocity in the 2nd term on the right is interesting. The 2nd term again is the viscous force on our particle due to velocity gradients in the surrounding fluid. At first you'd think the first derivative would be OK. But the 2nd is needed for the shear force because if the velocity gradient is linear shear drag from neighboring particles below = shear push from the fluid particles above above and our fluid particle gets no net viscous shear force so doesn't accelerate.
The trouble with the Navier Stokes equation is that even though it makes sense for
looking at one fluid particle swimming amongst all its neighbours, if you don't know what the neighbours are doing you've got a real problem. The Navier Stokes Equation is very difficult to solve.
Sorry got sidetracked by the non-newtonian fluids and tried to demystify the Navier Stokes equation. Took me ages to work out what that famous equation was on about years ago. Do windsurfers need to think about things like this? Maybe maybe not. I've got the red/yellow arrow day off work)
But back to our no.1 issue. 
The bubbling reduces the overall density but the biggest bonus is that the bubbles give it some compressibility, which means the above form of the equation is no help at all.
i dont think its that unreasonable to think that he broke his wrist by just hitting the water
just bend your wrist upwards and lean against the wall you can feel loads of pressure there, probbly only took a split second impact to snap it, plus it look shallow there as well
apparently the best method to destroy the strongest ship or submarine is to release suddenly adequately big gas bubble under the bottom of that ship....
we know air bubble is not a vaccum bubble that pressure exert is exactly the same as by surronding water on the ship
Just found out that you guys are going very deep to see if this is possible by only touching the water... Even heavy scientific formules passing by. Very interesting !!
Unfortunately Angelo (who was capturing for Ghosts of Speeds) did'nt had my crash on camera.
Didn't touch anything but water. You can see on the video that i released my gear and that there is quite some distance between myself and my gear (didn't cut into that video fragment) in just 2 seconds. I also had to swim a few meters before reaching ground. The only thing I can think off is the forward motion (GPS showed 74,7 kmph analysed via GpsResults just a split second before the crash). Probably my right wrist touched the water first, bending my elbow and followed by the mass of my body (including 10 extra kgs of lead) which snapped my wrist.
I did had a similar crash a few months earlier damaging my hand as well (not same place on my hand and only a few weeks out).
That day we were with 3 having spinout at the same place... Very weird in the middle of your run, not shooting yourself off into the chop. Maybe seaweed? Currents? Couldn't get out of spinout, so i've choosen to let myself drop op my back (first releasing the harnesslines off course). It's a human response to make yourself 'big' and spread your arms (wrist down) while falling on your back into the water. Just try it out in a swimming pool! Best reaction would have been how ever : both arms crossed, making yourself as little as possible. Not easy to learn i guess...
Next year I'll be back on the water and yes with gps, but not as extreme as it was this year. Sold my smallest speedboard (43W, 54L). Guess i'll go for alpha, hour, distance and fun !!
B42 breaks his other wrist masturbating, again.
This time covers it up with a "biking accident".
