01 February 2005

David Shaw's Forensic Report

Much has been written in the lay press regarding the death of David Shaw on 8 January 2005 in Bushman?s Gat near Danielskuil in the Northern Cape, South Africa. There has been much speculation on the cause and the accuracy of reporting has been highly variable.

In the interest of dispelling myths, providing closure and doing justice to the memory and dignity of the deceased, we have reviewed all the evidence and prepared this report. Our objective is to provide an evidence-based answer to the cause of David?s death. While the forensic investigation has not been concluded, and some uncertainties remain, our conclusions ? based on facts and materials that are already in the public domain ? are unlikely to yield significantly to the admission of further evidence. We have examined the actual diving equipment; analyzed the gas mixtures used; critically reviewed of the video footage from David?s camera; re-enacted the breathing patterns on the Mark 15.5 rebreather to capture the last 10 minutes of David?s life; and re-enacted the orientation of the deceased in relation to the body and the associated equipment. These are our conclusions:

David successfully reached his objective, but was unable to recover the body of Deon Dreyer at the bottom of Bushman?s Gat due to a number of unforeseen practical factors. He appropriately aborted the attempt at 6 minutes ? as planned ? but subsequently became entangled in the line previously used to mark the body. In the ensuing effort to free himself he succumbed to the combined effects of carbon dioxide build-up and nitrogen narcosis. It is certain that David died due to drowning after a loss of consciousness underwater, approximately 22 minutes after leaving the surface, at a depth of 264 meters.

As he had enough gas reserves, the question is ? why? The evidence suggests that David suffocated. Overfilling of his rebreather appears to have prevented him from exhaling properly. To illustrate this mechanism, imagine someone breathing out into a full bag of fresh air. Irrespective of the fact that the equipment (the bag) is fully functional and the gas (fresh air in this example) is safe, the inability to effectively breathe out results in a rise in carbon dioxide. The breathing impairment, combined with the increased activity of recovering the body, led to a critical build-up of carbon dioxide over a period of 10 minutes. This is sometimes called ?deep water black-out?.

David became increasingly incapacitated, eventually lost consciousness and ultimately drowned. While relatively swift, the duration of the process favors carbon dioxide build-up as a cause rather than a lack of oxygen. Nitrogen narcosis may have significantly interfered with his ability to solve the problem before it was too late. Calculations suggest that he may have experienced the narcotic equivalent of a 44 meter dive on air, but that this would have been compounded significantly as the carbon dioxide levels rose. Once he lost conscious, drowning became inevitable.

This tragic event is unlikely to stop deep cave and technical divers from pursuing the call for extreme exploration. Unfortunately, not only does diving become extremely hazardous at these depths, but also the effects of even simple problems are rapidly compounded as illustrated here. We hope that this may encourage such divers to be sensible and realistic about their ambitions for depth. Even David, who was a highly trained and experienced technical diver, was not immune to the dangers...

Source: www.iantd.co.za/home.html


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