Sec. 605. Section 301 (a) (2) (A) of title 37, United States (Code, is amended to read as follows: “(A) during one calendar month: 48 hours; however, hours served underway in excess of 48 as a member of a submarine operational command staff during any of the immediately preceding five calendar months and not already used to qualify for incentive pay may be applied to satisfy the underway time requirements for the current month.”.