Casabianca does not have Submerged Shot. It can't fire at other subs. Its bizarre, and its the only sub in the game without the SA, but it was never errata'ed.
I wish to have no connection with any ship that does not sail fast; for I intend to go in harm's way. - Captain John Paul Jones
Its not a horrible boat at 9 points, but the lack of Submerged Shot is definitely a handicap in this game. The fact that its the only sub that ever got published without Submerged Shot suggests it was probably an early set miscalculation by the designer.
I wish to have no connection with any ship that does not sail fast; for I intend to go in harm's way. - Captain John Paul Jones