15 CFR §998.52

1. (a)A professional mariner earns shore leave at the rate of one day of shore leave for each 3 and one-half consecutive days of assignment to a NOAA ship such that a total of up to 4 days of shore leave may be earned in any given pay period.
2. (b)For a professional mariner, an assignment begins either on the date he or she assumes their duties aboard a NOAA ship or on the date he or she comes aboard when a voyage is in progress. The assignment terminates on the date he or she ceases to be assigned to a NOAA ship or on the date on which he or she is released from assignment of their duties.
3. (c)In computing days of assignment, the Administration shall also include:
   1. (1)The days a professional mariner spends traveling to join a NOAA ship to which assigned;
   2. (2)The days a professional mariner spends traveling between NOAA ships when the employee is assigned from one NOAA ship to another; and
   3. (3)The days on which the professional mariner is on sick leave when he or she becomes sick during an assignment (whether or not continued as a member of the crew) but not beyond the termination date of the assignment to the NOAA ship.
4. (d)In computing days of assignment, the Administration shall not include days the professional mariner is on any kind of leave other than sick leave.