I believe even a Carrier is referred to as a ‘boat’, though it is also classified as a ship.
NOT in ‘my Navy’...
A boat is something carried by a SHIP...
Subs don’t or didn’t count, they were considered boats.
Guess it is a ‘Navy thing’...
Like the word SECURE...
In the Marines secure a building means blow it up.
In the Army it means surround it and get it under control.
In the Navy it means make sure all the doors are locked and lights turned off.
In the Air Force, it means take out another 20 year lease.
All in who one is talking to....