A bill to amend section 502(a) of the Merchant Marine Act, 1936.

Extends the construction-subsidy provisions of the Merchant Marine Act through 1976. Provides that the construction differential subsidy shall be equal to or less than 39 percent in fiscal 1974, 37 percent in fiscal 1975, and 35 percent in fiscal 1976. (Amends 46 U.S.C. 1152 (a))