NURC/Ambient Pressure Diving Technology Development Mission

NURC / Ambient Pressure Diving Technology Development Mission

Principal Investigator: Craig Cooper, NURC/UNCW
Training: May 19 — 20
Mission: May 20 — 24

Parallel to an increase in popularity and safety of recreational rebreathers in recent years, so too has the scientific community expressed an interest in rebreathers. Aquarius for many years has sought to incorporate rebreathers into saturation to meet the increasing interest expressed by scientists. Unfortunately the incompatibility of recreational rebreathers' computer algorithms with the saturation environment, and misbeliefs about time required for maintaining the rigs pre and post dive, presented problems that were unable to be resolved, until now. Working with US Navy divers, and their Specialized Research Diving Detachment (SRDD) in particular, has shown NURC that rebreathers can easily be maintained in a saturation environment, and resupply of consumable gases and CO2 absorbent can easily be handled throughout a mission. The Navy's MK 16 Underwater Breathing Apparatus (UBA) worked flawlessly throughout six saturation missions in Aquarius, so our next step was to find an affordable recreational/commercial rebreather that would function as well as the military UBA.

The Ambient Pressure Diving Ltd. (APD) Inspiration rebreather appears to have the compatibility necessary for diving from the saturation environment of Aquarius. This is due to: APD has been able to modify the Inspiration's Vision electronics to calibrate the oxygen cells at depth, and also modify its onboard dive computer for gauge mode; the CO2 canister is large enough to take full advantage of existing Aquarius downward excursion tables; and perhaps the greatest advantage is the Inspiration's ability to adjust oxygen partial pressure (PPO2) low and high settings to match the oxygen partial pressures of the excursion tables. This capability, along with the CO2 canister's duration and low gas consumption, is what may allow a diver on the Inspiration to stay out and work for 3-4 hours without having to refill oxygen or diluent tanks.

During this 4 day saturation mission, the divers will specifically test the Inspiration in the following areas:

Safety

Practicality of pre and post dive maintenance and resupply of consumables while in saturation

Durability of the units throughout multi day missions in the saturation environment

Ability to take full advantage of the NOAA SAT excursion tables with adjustable PPO2 settings

CO2 canister duration

Gas consumption on downward excursions

Equally important will be developing the training requirements for saturated aquanauts diving the Inspiration on downward excursions. Present aquanaut training using overhead diving techniques and open circuit scuba runs five days. The NURC trainers and Inspiration instructors will forge training requirements for a saturated rebreather aquanaut that will incorporate all the present safety briefings to cover excursion emergencies and habitat living. It is hoped that the replacement of open circuit scuba with rebreathers will still allow training to be completed within a seven day period, without any compromises to safety.

Benefits of rebreathers to both the Aquarius program and the scientific community include, but are not limited to: less wear and maintenance on topside air compressors due to lower gas consumption compared to filling scuba tanks; decrease in use or elimination of underwater fill stations and their high pressure umbilicals; increased time spent on science and less time spent filling tanks; and scientists studying fish can get closer to the subject, due to the lack of bubbles and virtually no ambient noise.

It is hoped that this "test and evaluation" saturation mission, pairing up Inspiration instructors and NURC trainers, will answer these questions and more, continuing the success attained with military UBAs, hopefully to soon offer rebreathers to scientists working from Aquarius.