Six is the minimum. Three each coast. Then you can run the one in maintenance, one training/transition, one operational dance. Always have at least one submarine per coast available likely two in a pinch. Though I really think more subs west coast would be better.The people that I deal with is thinking 6 so not to have any operation gaps and to account for unexcepted incidents. The crews are going to be reduced as well or at least that's the intent through automation and really available crew will be a major deciding factor on any purchase we make.