Tried to extract a data set from S&P Sea-web using categories “tankers”, “bulk carriers”, “dry cargo/passenger” and “offshore” built between 1/1960 and 1/2028 (projected) and gross tonnage above 500 GT. There’s certainly room to improve the query, filtering and post-processing, but this should give you an idea of how the number of hulls built in the US has changed over the years.
