The US was never a commercial shipbuilding hub once the transition was made to metal ships. During the timber ship era, the huge quantities of quality lumber th

The US was never a commercial shipbuilding hub once the transition was made to metal ships. During the timber ship era, the huge quantities of quality lumber the US had meant that they were world class at shipbuilding, but metal ships? Not so much outside of direct production for the World Wars(1). I mean, the fact that the US passed the Jones Act in 1920 is a pretty strong signal that even then the US was not viable in commercial shipbuilding. The US Navy, which has been tied for the largest or exclusively the largest in the world for over a century, meant that military shipbuilding was in a better state(2) but still not super competitive- few countries have ever bought the direct products of American yards- yards in the US mostly serve the USN and then sometimes the USN will transfer ships they don't need to other nations. 1: And even then, a whole lot of it was unskilled people learning by doing, and making mistakes. 2: There are many caveats, but it appears that British shipyards were probably more manpower efficient building warships than the US was in WW2. D.K. Brown discusses the evidence in _Nelson to Vanguard_. It's not perfectly clear- because hours were charged to contracts differently in the two countries, the fact that British ships charged fewer hours to a ship doesn't necessarily mean that they used fewer hours in actuality (while everyone counted laborers on a dock for hours, how do you handle hours spent doing accounts payable? Or material deliveries, or training? There are differences in how they were counted between countries, and Brown was unable to correct for them). It is also true that the US produced warships faster chronologically, so it is possible that the US threw so many bodies at ship construction that they went past the point of manpower efficiency to get less time spent in the yards. But, overall, British shipbuilders seem to have been more manpower efficient than US yards during WW2, as far as warship production.