In the enforcement of the Act, an employee will be regarded as
``employed as a seaman'' if his work as a whole meets the test stated in
Sec. 783.31, even though during the workweek he performs some work of a
nature other than that which characterizes the service of a seaman, if
such nonseaman's work is not substantial in amount. For enforcement
purposes, the Administrator's position is that such differing work is
``substantial'' if it occupies more than 20 percent of the time worked
by the employee during the workweek.