Section 6(b), with paragraph (2) thereof, requires the employer to
pay to an employee, ``if such employee is employed as a seaman on an
American vessel, not less than the rate which will provide to the
employee, for the period covered by the wage payment, wages equal to
compensation at the hourly rate prescribed by paragraph (1) of this
subsection for all hours during such period when he was actually on duty
(including periods aboard ship when the employee was on watch or was, at
the direction of a superior officer, performing work or standing by, but
not including off-duty periods which are provided pursuant to the
employment agreement).'' The ``hourly rate prescribed by'' paragraph (1)
of the subsection is the minimum wage rate applicable according to the
schedule shown in Sec. 783.23.