Surface logistics and consumables for open-circuit and closed-circuit deep mixed-gas diving operations

A series of eight dives, four with open-circuit scuba and four with closed-circuit rebreathers were made to compare the two diving methodologies. Two criteria were considered: time requirements for topside equipment preparation, and consumption of expendables. The open-circuit divers required four times as much topside equipment preparation as the rebreather divers, consumed 17 times as much gas, and cost seven times more in expendables. These findings indicate significantly less time and an infrastructure are needed to support closed-circuit rebreather diving rather than conventional open circuit modes for deep mixed-gas work.