The hull numbers actually make sense if you go by the Franz Joesph number system up to a certain point. If you accept the notion that most of the Constitutions are numbered in the 16xx range, then it doesn't. (The Maintenance chart that everyone started taking as "THE LIST" of Constitutions, it was very clear to me from the original VHS that that list was the ships that were currently at that base for one reason or another) Sometime after the Excelsior they obviously did away with the old system of batching hull numbers for each class of ship. (Constitutions start at 1700, Mirandas start at 1850, Excelsiors start at 2000, whatever other classes in the middle) At that point they just assigned ships the next number in sequence, but to account for all the hull numbers, 38000 commissioned (and decommissioned) ships in just over 80 years, and 30000 more just seven years later, one does have to wonder just what they were assigning hull numbers to. It's possible that they started assigning hull numbers to non-military ships (The Raven is a good example of that) its also possible that a number of ships were commissioned during the Cardassian War, the flare up resulting in the Tomed Incident, and the Borg scare, but never completed. A number of hulls were commissioned by the US Navy during the tail end of WW2 that were never actually built.