To amend the coastwise trade laws of the United States to authorize certain freight vessels to transport common ground clay as bulk cargo.

Amends the Merchant Marine Act, 1920 with respect to the prohibition against transport of merchandise in any vessel other than one built and documented under the laws of the United States and owned by a U.S. citizen, or one extended the privilege of engaging in the coastwise trade. Exempts from such prohibition the transport, as bulk cargo, of merchandise that is common ground clay on a freight vessel specifically designed for the carriage of such merchandise if the Secretary of the Treasury determines that a U.S.-flag freight vessel (crewed by less than 15 persons of either foreign or U.S. citizenship) is not available. Directs the Secretary to make such determination within 72 hours after receiving the necessary information.

Amends Federal shipping law to revise certain eligibility requirements to require a vessel to be issued a certificate of documentation with a coastwise endorsement (restricting use to the carriage, as bulk cargo, of common ground clay) if it: (1) is eligible for documentation, is of at least 5,000 net tons, and is designed for the transportation of common ground clay; (2) is a freight vessel that was not built in the United States; and (3) otherwise qualifies under U.S. laws to be employed in coastwise trade authorized under the endorsement.