Watch Angels
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Watch Angels

The Bühlmann Story. Episode 4

Developing procedures for carrying out long-term dives at depths of up to 700 m

In November 1963, A. Bühlmann, Shell International Research and Micoperi agreed a research and consultancy agreement. A. Bühlmann also became minority shareholder in a collecting society for intellectual property rights with the majority shareholders Shell International Research and Micoperi.

The contract provided for the establishment of a positive pressure laboratory at the University of Zurich with the aim of developing procedures for carrying out long-term dives at depths of up to 700 m.

As a doctor, Bühlmann was no longer interested in spectacular records, but in safe decompression procedures for professional divers on long-term dives to great depths. The entry of Shell International demonstrated the future importance of professional diving in the development of new oil and gas fields in the area of the continental shelf.

It has to be noted that A. Bühlmann was solely responsible for the implementation of the research program at the University of Zurich that he agreed annually with Shell International and Micoperi. He had contractually guaranteed the freedom to publish the results of the research work.

At the beginning of the construction of the overpressure laboratory in 1964, Hannes Keller was responsible for the technical implementation. Soon, however, Benno Schenk took over responsibility for the construction, maintenance and operation of the system. Research in a scientific environment, as it was practiced in Zurich after 1964, no longer corresponded to the ideas of Hannes Keller. Although their professional paths parted, A. Bühlmann and Hannes Keller remained on friendly terms until his death.

For A. Bühlmann, the clear separation of research activities in the laboratory and the practical implementation of the research results under realistic operating conditions was essential after his experience with the world record attempt in California.

The prerequisite for this was professional organization in both areas. Shell International and Micoperi took over responsibility for the practical implementation of the research results of the hyperbaric chamber laboratory at the University of Zurich after 1964. For this purpose, they built the Capshell in 1966, a hyperbaric chamber designed for long-term experiments in the sea.

In 1965 and 1966, over 100 long-term experimental tests were carried out in the hyperbaric chamber of the University of Zurich. They form the prerequisites for long-term dives, i.e. for the attempts at saturation in the Tyrrhenian Sea near Porto San Stefano to a depth of 220 meters, which took place from September 14th to October 24th, 1966.

“Capshell” was a ring-shaped hyperbaric chamber with several divisible compartments. The design was based on the assumption that the overpressure chamber would be lowered along the drill string. The pressure chamber was generously dimensioned so that divers could stay under pressure for several days, even weeks, to carry out repeated work assignments. During the test days, the Capshell was repeatedly lowered to the target depth at the place of use while hanging from a crane.

With these successful experiments it was proven for the first time under real conditions that long-term dives to great depths were possible. Under the direction of Cdr. J. Carr of Shell International conducted the series of tests without incident. These practical tests were a prerequisite for the later assignments of hundreds of professional divers who, after the oil crisis of 1973, undertook more and more diving assignments in connection with the development and operation of new oil and gas fields.

Under the direction of A. Bühlmann and Prof. Dr. H. Mattys was in the Medical Center of the Royal Navy in Alverstoke / UK from 3 to 10 February 1969 a saturation attempt on 300 m with several descents to 350m was carried out.

Alverstoke 350m record

The year 1969 was connected with another important event for research in diving medicine. In that year the first diving swimmer recruiting school of the Swiss Army was held. After diving in Lake Silvaplana at an altitude of 1,800 m above sea level, two out of eight divers had symptoms of paralysis in their legs.

The divers used the then common French GERS decompression tables, which were valid for sea level. The two divers were treated successfully in the one-man pressure chamber according to my father’s telephone instructions. As a result, decompression tables for air dives at different altitudes were calculated in Zurich for the first time on the basis of experiments with the combination of positive and negative pressure. These new tables were used by the Swiss Army from 1972 onwards.

Stay tuned for the next episode 5: Construction of the new hyperbaric chamber at the University of Zurich

Learn more about the Bühlmann watch project

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