The unit of time to be used in determining the application of the
exemption provided by section 13(b)(6) or 13(a)(14) to an employee is
the workweek. (See Overnight Transportation Co. v. Missel, 316 U.S. 572;
Sternberg Dredging Co. v. Walling, 158 F. 2d 678.) This is the period
used in determining whether a substantial amount of non-seaman's work
has been performed so as to make the exemption inapplicable. See
Sec. 783.37. A workweek is a fixed and regularly recurring interval of 7
consecutive 24-hour periods. It may begin at any hour of any day set by
the employer and need not coincide with the calendar week. Once the
workweek has been set it commences each succeeding week on the same day
and at the same hour. Changing of the workweek for the purpose of
escaping the requirements of the Act is not permitted.
