And then there would be a steady drain of cash to keep it afloat as a museum.
what? you don't think that the Democrats up there can't bleed away some tax money for this?
call it a "stimulus package" or whatever you want.
Plus the potential security issues with the hull would still be ever present requring security pretty much 24-7. And preventing access by divers in a public harbor would be difficult. The most cost effective option in terms of long term security would be to essentially dry dock it in a coffer dam and then fill it in with sand. And that is something of a less than glorious fate for a ship.
Actually.... that's been done before.
Not really for security reasons, but for Hurricane reasons. (and to keep the Navy from repossessing the ship back into active duty.
The USS Alabama (battleship) is moored in Mobile Bay as a museum. Hurricanes down there are a fact of life. A dam was built around the ship and filled with fill material (sand, rock, mud, etc). It's all below the waterline so you can't see it. (Mobile bay water is not clear).
Then they pumped the lower decks of the ship with sand to sink it into the sand heavy. This was to keep it in place in the event of a hurricane, but if we ever went back to war after it was put in a museum, then they were worried about it being called back into service. Bottom decks filled with sand make that harder to do.
this could be done for any of these museums, with enough funding to do it.