This subject comes up from time to time - anyway - it's an interesting read regarding where we are today...
On April 25, 1940, Congress adopted the Motor Boat Act of 1940 amending and adding to the Motor Boat Act of 1910. `Motorboats' were defined in the Act as `every vessel propelled by machinery and not more that sixty-five feet in length except tugboats and towboats propelled by steam.' The Act established four classes of motorboats; prescribed requirements for navigational lights and sound-signaling devices; life-preservers (what today are called Personal Flotation Devices); fire extinguishers, backfire flame arrestors and bilge ventilation.
The Act established licensing requirements for the operator of a motorboat carrying passengers for hire and specifically stated that, `No person shall operate any motorboat or any vessel in a reckless of negligent manner so as to endanger the life, limb, or property of any person.' 54 Stat. 163.
In 1940, Congress amended the Revised Statutes `to provide for the safe carriage of explosives or other dangerous or semidangerous articles or substances on board vessels; to make more effective the provisions of the International Convention for the Safety of Life at Sea, 1929, relating to the carriage of dangerous goods.' 54 Stat. 1023.
In February 1942, the functions relating to safety of life at sea, marine inspection, seamen's welfare and certain other maritime activities carried out by the Bureau of Marine Inspection and Navigation were temporarily transferred from the Department of Commerce to the U.S. Coast Guard (by executive order) for the duration of the war and until six months after the end of hostilities. The Coast Guard was responsible for those safety matters that had been regulated by BMIN: Approval of plans for merchant ships and their equipment; inspection of vessels to check stability, fire control or fireproofing, life-saving and fire-fighting equipment; administration of load line requirements; administration and enforcement of the laws pertaining to the numbering of motor-boats and the issuance of certificates of inspection; examination, licensing, and certification of Merchant Marine personnel--masters, pilots, engineers, staff officers; investigation of marine casualties; preparation and publication of rules and regulations to protect passengers, officers, and crews of American ships; Merchant Marine Council activities; and the training of merchant mariners.
In 1946, pursuant to Executive Order 9083 and Reorganization Plan No. 3, the Bureau of Marine Inspection and Navigation was abolished and became a permanent part of the Coast Guard under the Treasury Department.