[PSUBS-MAILIST] AIR TIME

A couple of post ago someone was talking about amount of breathing air ect. Someone mentioned that you had to carry 72 hours of by the Coast Card Rules are you all actually carrying that much air? and if you are what size tanks and how many of each are you using? The designs I had in mine were all two person with maximum air capacity of maybe 1hr to 1 1/2hr does this mean I have to incorporate 7 hours of air into my design?? To me that's a whole lot of air and I have to extend my design out like 50ft.