Its always interesting to me how battlecruisers tend to be longer than battleships, I always think the battleships would be the larger, but it is usually the battlecruisers instead.
longer hull more space for bigger machinery and also a mush sleeker hull, gives a higher speed. and Battle-cruiser was a class of ships that was intended to be fast. A battleship was different, they need just enough speed to get from A to B and do there missions, but be compact and powerful. Iowa class and Yamato class is something else tough... they are what you call fast battleship...