> The U.S. navy does have some very large aluminum ships

Unfortunately aluminum also rusts, it just happens to be a chemically stable and resistant rusting - but not in a stable enough manner to be mechanically/abrasive resistant, that's why you don't see them deployed in widespread use at stressing conditions like internal combustion engine blocks or fast ship hulls.

From said cited Wikipedia article:

> In February 2020 it was announced that the Navy plans to retire the first four LCS ships. On 20 June 2020, the US Navy announced that all four would be taken out of commission in March 2021, and will be placed in inactive reserve, because it would be too expensive to upgrade them to match the later ships in the class.