An acquaintance of mine showed me a device I had never seen before. He asked me if I knew what this device was? I could not answer him. I placed the device on my ULO page. ULO stands for unidentified laying objects. Not long after that Mr. Lain came forward and told me what kind of device it was.
This item “the triple rig” was a design for DCBA or Damage Control Breathing Apparatus and was not associated with diving. However my jpeg enclosed (under this article) shows an earlier variant of DCBA modified for 55MSW diving and called the SDDE or Surface Demand Diving Equipment, with the cylinders acting as air bail out.
This was an excellent design also using many of the parts in the better known mixed gas/oxygen Clearance Divers Breathing Apparatus CDBA.
There were only two small changes to convert from DCBA to SDDE namely an aluminium back plate and a small adapter to connect a surface supplied umbilical. No longer in service with Royal Navy but some overseas navies still call spares.
At the time the Royal Navy already had a SCUBA variant called the SABA set Swimmers Air Breathing Apparatus and the closed circuit oxygen and semi closed 60/40, 40/60 32.5 mixed gas clearance divers set called the CDBA for diving to 55 MSW both of these units worked well from the Gemini inflatable boats. However the surface supplied SDDE was difficult to operate from the Gemini due to having to have storage bottles, a diver panel, and two umbilicals.
Also at the time a deep water mixed gas semi closed variant was used for secret operations called the Mark 4C. Designed primarily for SUBSMASH this unit was used from 1975. Some aspects of the Mark 4 project may still be classified, I will check on this but incidentally working at 100MSW semi closed in cold 4 deg C water the maximum measured 02 uptake was 2.7 L/min at 63 MSW resulting in a P02 of 0.42 bar. The deep diving version of this unit was rated to 350MSW.
Pics of DCBA / SDDE below if you need more info let me know.
Iain, thanks for contributing to my website!
Therebreathersite was founded by Jan Willem Bech in 1999. After a diving career of many years, he decided to start technical diving in 1999. He immediately noticed that at that time there was almost no website that contained the history of closed breathing systems. The start for the website led to a huge collection that offered about 1,300 pages of information until 2019. In 2019, a fresh start was made with the website now freely available online for everyone. Therebreathersite is a source of information for divers, researchers, technicians and students. I hope you enjoy browsing the content!