Life-jacket possibility?

[mjcoon]

The idea of the foil was to make it at least visible to radar.

I thought that was called "chaff" and used to confuse radar, rather like a smokescreen.

(Edit: I think I confused the WW-II usage with the intended contemporary one, there!)

Mike.

 

[mjcoon]

CO2 isn't used for diving, it's a component of air, as is nitrogen. Divers (normal ones) use air in their cylinders. Advanced divers (or nutters, depending on your viewpoint) use oxygen and Helium to go deeper without the narcosis effects of nitrogen. They also reduce the oxygen content to reduce partial pressure and therefore the risk of oxygen poinsoning (yes, that's a real thing!) so often have almost pure helium in the cylinder - still a gas though, even compressed. They also use Argon in their suits to stay warm - useless for breathing though

I'm sure we've all seen TV programmes about deep diving and the Donald Duck voices of the divers using helium + oxygen.

Which reminds me that one of my party tricks on college Physics Department open days (for sixth formers) was to breath helium (and doing the voice) just by sucking on a liquid helium dewar. No problem with overdoing it and passing out because I'd have got frostbite of the tongue first!

Mike.

 

[grumpy_o_g]

I think submarines used to carry balloons to get an aerial up to a decent height when they surfaced to make radio contact - could be wrong though.

The big problem is the amount of cable you need to get it up to a decent height. In any decent wind the balloon would be bouncing around the surface and mainly just dragging the MOB downwind I reckon. I do like the idea of the inflatable aerial/light that some LJ's have tried though.

 

[Iliade]

We used to sell a tiny inflatable foil kite designed for just such a purpose. I cannot remember the name, but will edit this post if it comes back to me.

Helium cannot be readily stored compressed as it gradually leaks out of even the thickest bottles. If a light gas were required, it would probably be easier to come up with a dry solid which evolves hydrogen on contact with sea water.

 

[johnphilip]

todays best

Silly Fred, in fact a very silly fred.

 

[boomerangben]

Kites and balloons are not going to make you very popular with your rescuer, particularly if its a helicopter: the risk of entanglement would be substantial. To be visible on radar over surface clutter would need a big balloon. Far better off with a SART or PLB and a day night flare.

Edited to add: also a risk of getting the line wrapped around your neck/arms/legs

 

[LadyInBed]

O2 poisoning must be pretty well known. I remember that from my diving days but must admit it's so long ago that I've forgotten the relevant partial pressure.

One bar
In ye olde days 'frogmen' using oxygen re-breathers were restricted to less than 30ft.

Less than symbol comes out as <