[viacoffee]

Yeah, about that... None of what you said would work. People think water is this "cushion" like thing. In reality it is as solid as a brick unless the surface is broken (the mattress is not enough). A human would just end up breaking every bone in their body attempting to do this.

[vatotemking]

"HITTING THE OCEAN IS ESSENTIALLY THE SAME AS COLLIDING WITH A SIDEWALK" -from the article

[tunap]

If a large article of debris hit prior and you entered the churning, bubbling water(and not hit the debris), you may get off with just broken toes, feet, hips...maybe. Of course, you'd likely drown before you could swim back to the surface.

Chris MaClugage jumped a ski over three houseboats in Havasu a few years back. They aerated his landing area to buffer the landing/impact. Seems to have worked...

https://www.google.com/url?q=https://www.youtube.com/watch%3...

[justinph]

Mythbusters tested this: https://en.wikipedia.org/wiki/MythBusters_%282003_season%29#...

You still die:

Dropping Buster with an internal accelerometer from a crane led to difficulty because the dummy continually lost parts on each control impact. Eventually, they managed consistent drops (mostly just below 300 g), finding that the hammer reduced the impact slightly, but the 150-foot (46 m) fall would still be lethal.

[slavik81]

It seems they tested whether a hammer could break the surface enough. Larger debris would create a significantly larger disturbance and would probably be more effective.

[nickpsecurity]

Did they test proper landings or drop it randomly? That's a critical thing left out of many analysis. You learn its importance to preventing injury in both martial arts (esp relaxing or break falls) and military, jump school. The methods for high falls should be tested on each of those techniques given prior effectiveness.

[nickpsecurity]

Which is specifically why I put a cushion above water with potential mechanisms for breaking it.

[vatotemking]

Perhaps an air filled cushion is better than a mattress. Once the subject hits the cushion, it deflates. That would absorb much of the impact and prevent bouncing.

[nickpsecurity]

I've dove in water enough to know this is true. Couldn't recall mechanics of breaking surface properly, though outside basic dives. Modification: something between the mattress and water to break the surface. Maybe repeating structures that do that in a single layer. What now?

[tim333]

Indeed. The practical design is probably something more like a large air bag as used in ski jumping http://www.magicfr.com/wp-content/uploads/2014/09/babsnowboa...

[nickpsecurity]

Yeah, I'm thinking along those lines. I had the thing in mind I see in movies rescuing jumpers and a BouncyCastle. It works for small distances. How to get it to work for larger distances and with potentially other materials?

[tim333]

I imagine the big airbag/bouncy castle thing would work for free fallers. You'd need it to be quite thick like 50ft and quite large so you don't miss it jumping out of the plane. From mountaineering I think polyester tends to have the best strength to price ratio. There's a supplier here that can make 800 tons / month at about $2000/ton. Say 1 kg/m2 and .5 km x .5 km = 250 tons = $500k. Plus airpumps etc. Kickstarter?

[nickpsecurity]

Polyester seems interesting for it. A Kickstarter would be funny on this. I'm still at early exploration phase. Holding off.