Amending Merchant marine act, 1936, as amended, supplement to hearings before subcommittee on martime affairs, 81st Congress, 2d session, on H. R. 3289, H. R. 3337, H. R. 3930, H. R. 4190, H. R. 4847, H. R. 5346, May 31-July 7, 1949.