Analysis
HTS 8904.00.00 covers tugs and pusher craft under heading 8904 (tugs and pusher craft).
There is no general-rate duty on this line, which puts it with roughly 53% of the 32 tariff lines in chapter 89 that are also free. Free here means free of the base duty only: origin-specific Chapter 99 duties such as Section 301 can still be owed.
It is the only US line under subheading 8904.00, so the six-digit code used by every Harmonized System country and the eight-digit US line describe the same goods; a foreign tariff or an exporter's invoice showing 8904.00 points straight here.
Census statistics map these goods to NAICS 336611 (Ship Building and Repairing), an industry of 497 US establishments employing 99,786 people, the industry a domestic producer of these goods reports under.
The general rate of Free has not changed in any edition of the schedule since Jan 2023.