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Don’t you hate it when, 15 minutes into your dive, you and your buddy become separated and, because we are all safety conscious, after two minutes of unsuccessfully looking around for bubble streams or a patch of a yellow cylinder in the haze, you head reluctantly for the surface. I’ve had this experience on a number of dives.  One recent event is worth recounting.

It was a boat dive in open water to a reef at 15 m.  The visibility was about 5 m. The surface current was strong and my buddy (a dive instructor) and I descended rapidly to the reef below and set off just west of North into the current looking for crayfish and that photo opportunity of a lifetime. We’d being progressing steadily when I noticed a Blue Maomao behaving very peculiarly, rubbing itself on a kelp stem. I moved in for the photo.  On closer investigation the beastie had been foul hooked and the nylon filament had entangled in the kelp. Prior to the dive we’d been fishing to kill deco time. A couple of the lads had lost their lines following strikes and this was clearly the result of one of those incidents. My buddy and I set about freeing the fish and with no thanks it darted off to live another day. Photo opportunity gone we set off again on our bearing, buddy leading. I’d covered about 5 m when I was pulled up short by a fin. The nylon filament had tangled around my left foot (and as it transpired, also my dive knife and a clip on my BCD). Darn!  I deflated my BCD, settled on the reef, and set about untangling the line.  My buddy, oblivious to my peril, had disappeared. After about five minutes I’d identified and cleared all the snags. But my buddy was nowhere to be seen.  I like to dive by the book so I figured I had about two minutes to link up or head to the surface. I set off with purpose on our original course and after about two minutes aborted the dive.  During my accent the current carried me back just to the stern of the dive boat.  They noted my presence and left me to drift with another diver, picking us both up some ten minutes later.

If only I’d been able to locate my dive buddy. He’d continued on the designated heading and, having decided that I had been distracted by a photo opportunity, completed the planned dive alone.

Some weeks earlier I had been diving with Ivar (he features in the Great Barrier photo gallery – check him out).  Ivar had a nifty sonar gadget for finding the boat. It comprised two devices housed in clear plastic cases, each turned on by a magnetic reed switch. One unit was a sonar transmitter hung from the boat.  The other device was a receiver carried by the diver to locate and home in on the transmitter signal. It had a couple of LEDs for direction finding. I don’t know if Ivar had to extend his mortgage to buy the gizmo but he did say that it wasn’t cheap.

Navigation has never been an issue for me in my limited diving experience. Sometimes I have been slightly embarrassed by the current but I am usually not too far off the mark and I’ve never felt totally lost in inner-space. But linking up with a lost buddy is another matter.  Have they surfaced unexpectedly?  Have they back-tracked to look for something? Are they following a turtle, ray or shark? Or maybe I’m at fault. Perhaps I did get distracted looking for the perfect photo opportunity? 

Hence my current project: a sonar buddy locator. The concept is a cheap, unobtrusive, neutrally buoyant sonar transceiver rated to a depth of at least 40 m for each diver.  It would allow either diver to locate the other should they loose visual contact.  The device might also be useful on night dives too and has potentially many other applications.

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