29 C.F.R. § 783.43
Section 6(b) requires, under paragraph (2) of the subsection, that an employee employed as a seaman on an American vessel be paid wages at not less than the rate which will provide to the employee, for the period covered by the wage payment, wages which are equal to compensation for all hours on duty in such period at the hourly rate prescribed for employees newly covered by the Act's minimum wage requirements by reason of the 1961 Amendments (see §§ 783.23 and 783.26 ). Although the Act takes the workweek as the unit of time to be used in determining compliance with the minimum wage of overtime requirements and in applying the exemptions, Congress, in recognition of the unique working conditions of seamen and of the customs in the industry, made this special provision. Under section 6(b)(2) periods other than a workweek may be used, in accordance with established customs in the industry, as the basis for calculating wages for covered seamen provided the wages equal the compensation at the applicable minimum hourly rate which would be due to the employee for his hours actually spent on duty in the period. This would mean that the wage period may properly cover, for example, the period of a month or of a voyage so long as the seaman receives at the appropriate time compensation at least equal to the prescribed minimum rate for each compensable hour in that pay period. (See also § 531.26 of this chapter concerning requirements of other laws governing calculation of wages and frequency and manner of payment.) To illustrate, where seamen have customarily been paid monthly under an arrangement to perform seamen's duties during stipulated periods and to be off duty during stipulated periods during the month, if such a seaman works 300 hours during the month and receives his monthly compensation in an amount equal to a payment for that number of hours at the applicable minimum rate, there would be compliance with the requirements of section 6(b)(2). The fact that this seaman works a varying number of hours during the weeks comprising the monthly period or that the monthly compensation is disbursed in two or four partial payments to the seaman during the month would not warrant a contrary conclusion.
29 C.F.R. §783.43