((a)) ** In general** The Under Secretary may prescribe regulations relating to shore leave for professional mariners without regard to the requirements of .section 6305 of title 5

((b)) ** Requirements** The regulations prescribed under subsection (a) shall—

((1)) require that a professional mariner serving aboard an ocean-going vessel be granted a leave of absence of 4 days per pay period; and

((2)) provide that a professional mariner serving in a temporary promotion position aboard a vessel may be paid the difference between such mariner’s temporary and permanent rates of pay for leave accrued while serving in the temporary promotion position.

((c)) ** Professional mariner defined** In this section, the term “professional mariner” means an individual employed on a vessel of the Administration who has the necessary expertise to serve in the engineering, deck, steward, electronic technician, or survey department.