5 C.F.R. § 630.702
Extended voyage means a voyage of not less than 7 consecutive calendar days duration.
Oceangoing vessel means a vessel in use on the high seas or the Great Lakes; but does not include a vessel which operates primarily on rivers, other lakes, bays, sounds or within the 3-nautical-mile limit of the coastal area of the 48 contiguous States, except when used in mapping, charting, or surveying operations or when in or sailing to or from foreign, territorial, Hawaiian, or Alaskan waters, or waters outside its normal area of operations or outside the 3-nautical-mile limit.
Shore leave means leave authorized by section 6305(c) of title 5, United States Code, and this subpart.
Voyage means the sailing of an oceangoing vessel from one port and its return to that port or the final port of discharge.
5 C.F.R. §630.702