Hi Vance. I plan on using a scrubber and 02 feed. As a basic safety measure, I'll have two 40 cu. ft. tanks with scuba regs parked next to the windows where our faces are. These will be easy to grab the reg and open the valves. The two main ballast blow tanks are located at the rear of the sub cabin. Two additional scuba tanks will be strapped under the fin on the rear fairing. ( outside the cabin ) Back-up air just in case.
Total on board air will be four 80's for tank blows and two 40's for emergency breathing.
With 12 batteries for motors ( three in series for each motor at 36 volts ) and two more for controls etc. ( parallel at 12 volts ) it is getting a little crowded inside, but still roomy and everything is within easy reach from the sitting position.
Frank D.