Isn't it bad luck to rename a ship?
Not at all. Some older Great Lakes ore carriers have had as many as three names.
FWIW, the U.S. Navy doesn't follow any of these superstitions. For example, the ship christened USS Scorpion was renamed USS George Washington during construction. Tragically, it was Scorpion that was lost with all hands on May 22, 1968. I actually served on a ship that ended in the letter a, USS Atlanta, the fourth ship to bear that name. She was definately an unlucky ship, but not in a tragic sense. :)