5 CFR § 630.703 - Computation of shore leave.
(b) (1) For an employee who is an officer or crewmember, a voyage begins either on the date he assumes his duties aboard an oceangoing vessel to begin preparation for a voyage or on the date he comes aboard when a voyage is in progress. The voyage terminates on the date he ceases to be an officer or crewmember of the oceangoing vessel or on the date on which he is released from assignment of his duties relating to that voyage aboard the oceangoing vessel at the port of origin or port of final discharge, whichever is earlier.
(2) For an employee other than an officer or crewmember, a voyage begins on the date of sailing and terminates on the date the oceangoing vessel returns to a port at which the employee will disembark in completion of his assignment aboard the vessel, or on the date he is released from his assignment aboard the vessel, whichever is earlier.
(c) In computing days of absence, an agency shall include (1) the beginning date of a voyage and the termination date of a voyage; (2) the days an employee spends traveling to join an oceangoing vessel to which assigned when the vessel is at a place other than the port of origin; (3) the days an employee spends traveling between oceangoing vessels when the employee is assigned from one vessel to another; (4) the period representing the number of days within which an employee is reasonably expected to return to the port of origin when his oceangoing vessel's voyage is terminated, or his employment as an officer or crewmember is terminated, at a port other than the port of origin; (5) for an employee who is an officer or crewmember, the days on which he is on sick leave when he becomes sick during a voyage (whether or not continued as a member of the crew) but not beyond the termination date of the voyage of the oceangoing vessel or his repatriation to the port of origin, whichever is earlier; (6) for an employee other than an officer or crewmember, the days on which he is carried on sick leave but not beyond the date on which he returns to the port of origin or the termination date of the voyage, whichever is earlier; and (7) the days of approved leave from a vessel (paid or unpaid) during a voyage.
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