One key distinction between a ship and a tank that is, I think, being missed. When a tank is penetrated, it's usually out of action with one hit.
A ship is so big that it can take multiple holes and seal off the problem and keep fighting, most of the time. (Invincible, Inflexible, Queen Mary, and Hood are a few exceptions) The ships needed many shots to both get the hits, and do the damage, to take out the target. Also, the battleships usually carried close to the biggest gun that could be made at the time.
Within limits, a ship can be as big as desired--tanks can't.
A ship is so big that it can take multiple holes and seal off the problem and keep fighting, most of the time. (Invincible, Inflexible, Queen Mary, and Hood are a few exceptions) The ships needed many shots to both get the hits, and do the damage, to take out the target. Also, the battleships usually carried close to the biggest gun that could be made at the time.
Within limits, a ship can be as big as desired--tanks can't.