A Better Way to Find Lost Divers

Like many Great Barrier Reef-based dive operations, Mike Ball Dive Expeditions has not been immune from the past few years’ incidents of paying customers getting lost on dives and spending hours at sea before getting rescued. In our March issue, we reported on the two American divers who got separated from Mike Ball’s Spoilsport and treaded water for seven hours. To prevent repeats of that incident, Mike Ball Expeditions has been testing a new method for locating missing divers at sea. Trevor Jackson, the Spoilsport captain who led the tests, sent us this report.

Imagine being lost from your dive boat. You can see it in the distance searching, moving from side to side on the horizon. But it’s so far away, the effort to get to it is fruitless. Your hopes sink with the sun and pretty soon it’s dark. With no chance of being spotted for another 12 hours, your thoughts turn to survival, keeping warm, staying together, and conserving energy. Not a situation anyone would want to find himself in.

Recent infamous events here in Queensland, where two divers spent the night drifting around the Reef in the dark last year [Editors: see our report on that in the July 2008 issue of Undercurrent], prompted me to review what we aboard Spoilsport would do if we were faced with every dive boat’s nightmare - - divers who don’t return. So I decided on a practical experiment.

Early one morning, I made a fake human, dressed it in dive gear and threw it in the water before any crew had come on deck. I told the lookout on duty later to ignore the “diver,” and to give the crew no assistance later on when we went to find it. I let two and a half hours go by. We completed the early dive, and then I alerted the crew that we had a “lost diver,” who was last seen entering the water a few hours ago. An initial concentrated search of the horizon produced nothing. The diver was gone from sight.

We then tied a weight belt to a life jacket and threw it in.

There was a fair bit of wind and tide about, so the jacket would give us an indication of where to start looking. Surprisingly, the jacket took off in a direction contrary to where we believed the diver might be. Five minutes later we threw another weighted jacket in, followed by another a bit later. Pretty soon, the three jackets were forming a line leading toward the horizon. I instructed the helmsmen of both our dinghies to drive parallel to that line and head out for about a mile. Our fake diver was found, 27 minutes after the drill started and a mile from the boat; completely invisible to the eye and at 90 degrees to where we had initially expected him to be.

The experiment was both pleasing and sobering. The striking thing was that, despite what the conditions seemed to indicate, the diver wasn’t going in the direction we had assumed. We decided to build permanent markers to help locate drifting divers and store them on board Spoilsport for such an event. The result was the specially configured floats which you see in the photo on page 12. They include a strobe, built-in radar reflector and a flag, for use both day and night in any conditions.

We ran regular drills with the buoys to see how well and how consistently they worked. The more we practiced, the more convinced we were that the buoys were going to be a real revelation. The buoys were not only giving us direction but the rate of drift as well. If we knew approximately when the divers went missing, we could apply a little rudimentary math and figure out how far out they were also.

After starting a drill one day, I grabbed one of the crew and said ‘Come on, let’s try something new.” The dummy diver had been lost for an hour, and we had launched the two buoys 10 minutes apart. Because they were drifting now at the same speed as the diver, we could use the gap between them to get a reasonable idea of how far out we would need to go to find our dummy. Lining up the two buoys in the dinghy, we drove at top speed between the two and timed the ride - - it took 40 seconds to meet our diver. Because the buoys drift at the same rate as a diver, it was then simply a matter of dividing the time the divers were lost by the time interval between when the two buoys were launched. In other words, 60 minutes divided by 10 minutes, equaling six. We then multiplied the time it took for us to speed between the buoys, 40 seconds by 6, or 240 seconds. All we had to do then was keep the buoys in line and speed out in the right direction for 240 seconds, and our divers should be there, or at least pretty close by.

Over a year has passed since those drills. In dozens of tests, the buoys have given us the direction and distance of our lost diver dummies with stunning accuracy. There are certain conditions in which the buoys don’t work as efficiently but with constant practice and a good measure of common sense, we’ve trained all our crew to use the buoys to regularly locate dummies missing for up to two hours and at ranges up to three miles.

The safety of our guests and crew is of paramount importance here at Mike Ball, as it is for any professional liveaboard on the water. Based on those dummy trials, I know that in the event of an emergency requiring us to locate a diver missing on the surface, we are now one step ahead of the game.