Porpoise (make of scuba gear)

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Porpoise is a tradename for scuba developed by Ted Eldred in Australia and made there from the late 1940's onwards. It included:

1. A make of diving oxygen rebreather

This rebreather was developed by Ted Eldred in the late 1940's and early 1950's. Some were made and used for sport diving, but they did not go into full production. It was worn on the back without a casing. The bag was between the canister and valve assembly and the diver's back. It had two wide breathing tubes like an aqua-lung or an IDA71, running to a mouthpiece, which had a shutoff button to keep water out when it was not in the mouth. It appeared in three versions: MK1, MK2, MK3. It had a special valve that both breathing tubes ran through: it was activated by surrounding pressure; when he got deeper than was safe for pure oxygen it restricted (not stopped) the supply of breathing gas, to tell him to go to shallower depth. (Before open-circuit scuba was readily available in Australian, many Australian sport divers used war-surplus Siebe Gorman Salvuses.)

2. A make of single-hose open-circuit scuba

This was the first single-hose open-circuit scuba made in the world. Ted Eldred in Melbourne in Australia started designing it in 1948 to "design round" the Cousteau-Gagnan aqua-lung patent, and to get rid of air supply restrictions that affected early Cousteau-Gagnan-type aqualungs. He started making it commercially in 1952. The Australian Navy adopted it. It was the origin of single-hose scuba regulators. It was much used by Australian scuba divers. A picture shows a set with one cylinder with its valve at the bottom, strapped directly to the back with rucksack-type straps without backpack plate or buoyancy aid, with a single-hose regulator-mouthpiece which could be strapped in. The high-pressure regulator screwed into the side of the cylinder valve; there was no A-clamp.

References

Historical Diving Times No.36 Summer 2005
Historical Diving Times No.38 Winter 2006

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