Thursday, 30 December 2010

Free flow

You've trained for this sort of thing, sure... in that warm swimming pool, kneeling around the instructor, the surface an undulating mirror a few feet above your head.  Hold the button down on your regs, pretend its jammed, and as the air flows around you, take breaths from one side and let the excess stream past. Don't panic, you can still get air... just head to the surface and swim back to the boat. Just one more safety lesson they will teach you, one more you'll soon forget as you swim through multi-hued reefs and watch the myriad displays of sea life dance around you. Besides, you'll hear frequently that most regulator free flows take place on the surface, at sub-zero temperatures, not underwater in warm tropical seas.

And who in their right mind would be diving in sub-zero weather?

Our goal was simple... drop down to the bottom , take a bearing at the sunken airplane, then head off at 145 degrees until we reached the gnome garden.  My buddy would navigate, I would be running the camera - not at anything special, but I wanted to try capturing a continuous film of a dive, rather than my usual 30 second clips of an interesting fish or curious lobster.  The quarry with its limited distractions seemed as good a place as any to try and I had never been to the gnome garden before... and the cold weather?  Well, it promised a swim free of other divers, and hopefully a bit less of the algae that clouded the waters each summer.

Ten minutes in, and we have problems.  Free flows may be more common at the surface, but in water only a few degrees above freezing they can happen at any depth. At that moment we were 15 meters below the surface and my buddy was engulfed in a column of bubbles as his regs vented precious air.  This shouldn't be a problem... we are trained what to do, after all, but quarry diving in winter adds a few extra dimensions not covered in the training courses I took years ago. The first problem is the venting regulator - not only is it depleting my buddies air, but the bubbles are blocking his vision and threatening to knock free his mask - the last thing he needs is the shock of ice-cold water hitting his face if his mask comes free.  Taking off your mask in warm water is an unpleasant enough experience - when the water is three degrees I would challenge anyone not to panic.  This time, at least, luck is on our side, and he could switch to the spare reg on his pony bottle (a christmas gift - who would have thought he would need it so soon?) but with air going fast we needed to get to the surface.

The second problem of diving in cold water is that to even be in the water safely you need a dry suit. A dry suit is basically a bag of air that surrounds you, and much of the art of dry suit diving is learning to manage that bag of air so that you don't go shooting to the surface like a balloon.  This is accomplished by carrying large amounts of lead (15 kilos, in my case) to counteract both natural boyancy and the boyancy of the air in the dry suit.  Without a bit of air in the dry suit, one has a tendancy to go to the bottom.  Even with a secondary air supply, my buddy still needed air to control his ascent and to stay on the surface.  With thick gloves and frigid hands, creative solutions such as shutting off his main tank until we surfaced were out of the question.

Surfacing in murky water is harder than it sounds... you have no reference points, no sight of ground below or the surface above, only your depth gauge or dive computer to tell you where you are.  You don't want to go straight up - that risks the bends - but with a limited air supply,  patience isn't a virtue.  I think we spent the first 30 seconds finning away before we realized we weren't going anywhere - just bobbing back and forth a few meters above the ground.  Guided by the depth display on our computers, we slowly made our ascent to six meters, before my buddy signalled for us to halt our ascent, giving me the sign for a three minute decompression stop.  I was a bit surprised - ten minutes at 15 meters isn't long enough to need a safety stop - and the gauge for his tank was still dropping.  The back-up air supply had given him a bit of confidence - but maybe a bit too much - it couldn't inflate his boyancy jacket and with only a small air supply, he couldn't have had more than a few minutes left on his reserve.  Still... what could I do?  So there we were, hanging about at 6 meters, a stream of bubbles pouring from the regulator dangling at his side, while his gauge dropped into the red and I wondered when his pony tank would run out.  A minute and a half in, and I finally decide enough is enough - the surface was in sight, but any longer dallying about and he would never reach it. An executive descision had to be made.  Grabbing his jacket, I signalled upwards and began my final ascent, lifting him with me.  Only at the surface, his jacket now inflated with the last wisps of his air, could I finally relax. 

The long wait at 6 meters seemed to me a bit silly, given the circumstances, but it could have been different.  If we had been down longer, or deeper, a straight run to the surface could have had much more dire consequences... there is a reason that novice divers are told not to go below 18 meters, where optional stops become mandatory and the surface may as well be a hundred meters away for all that you can safely flee to it.

And as for my attempt at filming?  Turns out my camera has difficulties at cold temperatures.

I guess for now, its another 30 second short feature.

No comments:

Post a Comment