46 U.S.C. § 10501

(a)

Except for a vessel to which chapter 103 of this title applies, this chapter applies to a vessel of at least 50 gross tons as measured under section 14502 of this title , or an alternate tonnage measured under section 14302 of this title as prescribed by the Secretary under section 14104 of this title on a voyage between a port in one State and a port in another State (except an adjoining State).

(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.

(c)

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