If you were balancing the books, you could have a ????????at one side, while you waited to add in another sum. That's the 'count section'. If you had a lot of specific military vessels you would have a ??? ????? (a two word phrase).
It is a count of a section of the whole and could, read in a humorous way, be a count of a complete part of the fleet - normally referred to as “boats” rather than “ships”.