((a)) Except as otherwise specifically provided, this chapter applies to a vessel of the United States—

((1)) on a voyage between a port in the United States and a port in a foreign country (except a port in Canada, Mexico, or the West Indies); or

((2)) of at least 75 gross tons as measured under , or an alternate tonnage measured under as prescribed by the Secretary under on a voyage between a port of the United States on the Atlantic Ocean and a port of the United States on the Pacific Ocean.

((b)) This chapter does not apply to a vessel on which the seamen are entitled by custom or agreement to share in the profit or result of a voyage or to riding gang members.

((c)) Unless otherwise provided, this chapter does not apply to a foreign vessel.