By Bob Halstead
There is a very strange expectation these days that if you go diving from a boat you can, at the end of the dive, bob up anywhere in the ocean, and get picked up.
Life was never like this. If you dived from a boat you were expected to be able to get back to it, and end your dive at the boat ladder. If you were diving from a small boat without a separate tender and failed to surface right at the boat, you would have to swim for it or wait, drifting around for 30 minutes or so, shark bait, until all the other divers were on board before the boat could pick you up. If it could still find you.
On our boats we had a rescue tender but if you were picked up away from the main boat we considered that to be a rescue, and we used to charge for rescues. A crew member would take the tender and pick you up. To be assured of survival it was wise to carry $5 in your BC pocket.
Nowadays most diving seems to be from big boats with multiple tenders. Divers surface all over the ocean, inflate their safety sausages and get picked up – and no one charges anything. It is a pity because the rescue fee had multiple benefits including keeping the crew alert to surfacing divers, since the cash went to the crew member who effected the rescue.
The art of underwater navigation appears forgotten but it is not always the divers fault. For many years I was the proud owner of a compass fitted to a slate. The slate was useful because I could communicate to my buddy by writing such messages as “Where the heck are we?”. That is if I could find my buddy. She was usually lost too, but if we did find each other I could give her the slate and she could write “Which way to the boat?”.
The compass was great because we could spin it around and find magnetic North. Then South, East and West. Then South east, North-west … you get the idea. Unfortunately we did not need to know that, we needed to know where the boat was, and, since we had forgotten to set the compass at the start of the dive, we had no way of finding out underwater.
Anytime I had to teach students underwater navigation I would drag out the slate and compass and show them how to use it properly. Then I would set some sort of navigation challenge, perhaps a triangular course from boat to a couple of marker buoys on top of a shallow reef, and have the amusing experience of watching student divers bubbles stream off in all the wrong directions. With a bit of practice they would get the hang of it, especially the bit where you bob to the surface and see where the boat is.
All those years and I never realised that the compass had a trap waiting.
You see, the needle was symmetrical and to differentiate north from south all the manufacturer had done was paint one half black and the other red.
I sent my two eager students off on their navigation swim which was to descend to an aircraft wreck in 12 m of water then align the red point of the needle with the bezel setting (established on the surface) and swim in the direction shown by the lubber line. This would bring them into shallow water over a reef.
So I was a little bit worried when I noticed the divers bubbles heading in exactly the wrong direction into deeper, murkier water.
Luckily they remembered what I said about finding out where you are before it is too late, and bobbed to the surface to be rescued. During the fuss of getting into the inflatable tender, the accursed slate and compass detached from the diver and disappeared forever.
OK, have you worked it out already? – at depth, with the red light absorbed, the red appeared black and one end of the needle looked the same as the other. The result of an unlucky guess was to swim 180 degrees in the wrong direction. The generous student insisted on replacing the lost compass so I now have a fantastic luminescent fancy compass with a needle shaped distinctly like an arrow.
I went on a dive recently and got completely lost. So I bobbed up to see where the boat was. Then I remembered my new compass. Next dive I put it on – it has a wrist strap – got in the water and realised I had forgotten my computer, which also fits on the wrist. I had to get out and try again. My navigation was however perfect and I ended the dive right at the boat. And, if anyone had asked, I could have told them exactly where north was.