If you want some entertainment, look up the Jones Act fleet. I believe the biggest and most modern vessel in it is actually a foreign vessel that the US government seized from criminals and auctioned off.
Also the jones act not only requires the vessel to be US Flagged, but it must also be wholely owned by citizens of the united states, and either be US built or one of the following exceptions:
(i) was captured in war by citizens of the United States and lawfully condemned as prize;
(ii)was adjudged to be forfeited for a breach of the laws of the United States; or
(iii)qualifies as a wrecked vessel under section 12107 of this title;
The net result is that nearly half the US Flagged merchant fleet is not even Jones Act Eligible. Which seems pretty absurd.