The Magazine for Underwater Professionals
Tom Hennessy, MSc PhD CMTH FIMA FSUT, began diving in 1964 with the Cambridge University Underwater Exploration Group, while researching theoretical hydrodynamics at Churchill College. However, diving physiology took a hold and in 1973, as a senior lecturer in Applied Mathematics, he completed a PhD in the biophysics of inert gas exchange in decompression at the University of Cape Town.
During 1968-69, as diving officer of the Atlantic Underwater Club in Cape Town, he introduced a diver and instructor training programme based on the BSAC, later adopted as the national standard in South Africa, for which he was awarded the club’s premier Cdr Peter Keeble Cup in 1970.
As president of the South African Society for Underwater Science, 1975-76, he represented the special needs of scientific divers in new professional diving legislation. But the opportunity to do real decompression research lured him to the Royal Naval Physiological Laboratory (RNPL) in 1976 to work with Dr Val Hempleman, its world-renowned superintendent.
At RNPL he analysed all the deep heliox saturation dives that were done in the Deep Trials Unit and High Pressure Chamber during the period 1969-1979 and successfully calibrated a mathematical model of saturation/‘big drop long stop’ decompression dives which was used to design rules for safe saturation-excursion dives. As a principal research fellow he co-developed with Surg Cdr Tom Shields new RN trimix tables to 80 metres. Thereafter, as project leader he developed new excursion nitrox tables to 60 metres for the then Department of Energy, released in 1985 by the Construction Industry Research and Information Association Underwater Engineering Group (CIRIA UEG).
In 1984, concerned by the withdrawal of MoD support for diving research, he decided to transfer to the Admiralty Research Establishment (ARL) in Teddington as head of section in Non-Acoustic Detection and Wake Hydrodynamics, managing a large research programme in ship and submarine wake detection for five years. In 1987 he developed, in his spare time, the BSAC’88 Tables which became the standard for decompression training of BSAC divers throughout the world, and in 1996 introduced the BSAC Nitrox Tables. He was awarded the premier BSAC Colin McLeod Medal in 1991 for developing these new decompression procedures that were judged to be a significant improvement in diver safety and understanding of decompression procedures.
As a consultant to Wharton Williams Underwater Engineering Contactors he developed special long exposure air tables and special rules for planning multi-level heliox saturation/ excursion dives in commercial diving operations.
He later held the post of senior lecturer in Medical Informatics in the Centre for Measurement and Information in Medicine at City University and in 1991 he co-established the first MSc Medical Informatics course in Europe, jointly with Guy’s, King’s and St Thomas’ Medical School, and was its first course director to September 2001.
In 1990 he was a member of the European planning group that successfully launched an Erasmus MSc course in Health Informatics at the University of Athens, and he subsequently taught a module in Athens on the course over the next 10 years.
In 2000 he was awarded the Houlder Cup by the Society of Underwater Technology for his contibution to North Sea underwater diving operations.
In 2009 he produced new accelerated oxy-nitrogen decompression tables (the Ox-Stop Tables) for the British Sub-Aqua Club which used high oxygen mixtures during the ascent phase to shorten the ascent time.
In 2011 he was elected an emeritus member of the Undersea and Hyperbaric Medical Society of which he had been a member since 1972.
He published approximately 50 papers in diving physiology and decompression modelling and co-authored a book on nanoscale fluid dynamics in physiological processes. Tom had heart disease for 30 years and died after undergoing his third major heart operation. He is survived by a wife, two daughters, five grandchildren and a sister, his only sibling.