For the purpose of this chapter—
(1) “Secretary” means the Secretary of the Department in which the Coast Guard is operating;
(2) “power-driven vessel” means any vessel propelled by machinery; and
(3) “towing vessel” means any commercial vessel engaged in towing another vessel astern, alongside, or by pushing ahead.
(Pub. L. 92–63, § 3, Aug. 4, 1971, 85 Stat. 164.)