Years ago when I was a lowly postgraduate student in North Wales there was a mysterious case of a small fishing vessel that sank in relatively calm conditions in Cardigan Bay. Concerns were expressed by some that the boat had been sunk by a navy submarine and after the relevant court cases etc. the local BBC station decided to make a short documentary about the sinking and came up to the lab I worked in to interview an expert and do some filming. I was setting up some waves in a laboratory wave channel for them to film so I got to listen in on the whole process from start to finish (I also had my index finger filmed as I used it to press the ‘on’ button for the wave tank – if ever there was an impressive claim to fame surely that has to be it!).
At the start of the filming process the interviewer briefed the expert (I’ll not name them) about the line of questioning the interview would take and absolutely promised that they would not ask the expert whether the wave that swamped the boat had been caused by a submarine. You can probably guess what happened – the interviewer proceeded to ask about each possible natural cause of sinking and each was ruled out in turn. With no natural causes left the interview then dropped in the killer question – so could the sinking have been caused by a submarine? To which the expert was left with no answer other than an open mouth and an uncomfortable pauase before a hesitant “I suppose that is possible” type of answer.
Since then I’ve come across several reports about freak waves, sinking and damaging ships and there was a BBC science documentary about freak waves a few years ago. Now, there has been some new theoretical research which suggests that certain configurations of sand banks can cause freak waves, up to three times the typical wave size, to occur much more frequently than would otherwise be expected. The authors of the work, which was reported on the BBC Website [09 August 2009] are at pains to point out that their work is theoretical, but should be possible to test their work with measurements made in particular locations. If their work turns out to be correct and to have wide applicability then the world’s shipping companies will be beating a path to their door in no time at all.
Tim O'Hare 