Changes in Pressure from Swells

[CIBDiving]

This is an offshoot of a discusion I was having in the main forum about holding your breath. A claim was made that a person was embolized as the result of a swell passing over. I see no way this could happen! At least not at reasonable depths below the trough of the swell ( say 10 ft ).

It seems to me that those who believe a swell causes a change in "depth" are mistaken.
while the distance from the diver ( or bottom ) to the 'surface' directly above them will change, the pressure on the diver will remain constant. Therefore the "depth" is constant.

Can anybody provide data one way or the other?

A simple experiment comes to mind -
A clear tube extending from just above the bottom ( or a reasonable distance from the surface) through the surface and far enough up to remain above the 'wave' tops. With the water at rest the tube will fill to the water level.

Now imagine what happens as a wave passes - will the water in the tube rise with the wave crest and drop with the trough or will it remain at it's original level?

It is my contention that it will remain at a given level, not follow the wave.

 

[Diver Dennis]

I think if there was any change in depth to the divers position it would be greater since the swell has the most rise at the surface and less the farther you go down. In other words the diver would move up in the water column less than the rise at the suface, hence the deeper depth depending on the size of the swell. That is I THINK it makes sense.

 

[gangrel441]

I believe the concern would be over the depth change in the trough, not in the swell.

 

[Diver Dennis]

Aaaah, good point gangrel.

 

[Diver Dennis]

But would you not get the same action in the trough? I mean when the swell passes would it not deposit you in the same place in the water column?

 

[Diver Dennis]

Of course I may be way off here.

 

[HarleyDiver]

Are you holding on to somthing like a mooring line that keeps you in place, or are you completely neutral & floating a fixed distance from the surface? maybe even a lift bag?

It makes a difference.

 

[Spectre]

I believe the concern would be over the depth change in the trough, not in the swell.

In the case of the discussion at hand, that being of potential embellism, yea. [although I would argue it would also be an issue if you were inhaling as well]. But the crest would allegedly be an issue if you were, say, on a deco stop at 20ft on oxygen.

 

[CIBDiving]

I believe the concern would be over the depth change in the trough, not in the swell.

But is there a "depth" change AT ALL? Remeber we think of depth as "'how far down are we", but what matters is Pressure Not distance! The exact amount of water over your head means very little ( unless you're trying to swim up ).

 

[Diver Dennis]

But is there a "depth" change AT ALL? Remeber we think of depth as "'how far down are we", but what matters is Pressure Not distance! The exact amount of water over your head means very little ( unless you're trying to swim up ).

Pressure is measured by the amount of water, ie. weight, above us.