Navy Hull Numbers

That depends partly on the class of ship.  The hull numbers on a destroyer might be 8" at the bow, while those on a YTB might be 18", and those on a CV might be 12'. If you can locate the draft marks at the bow and stern, you should be able to scale the hull numbers.  Draft marks on USN/USCG/US Army ships are 6" high and spaced at 6" intervals. 

CVs have their hull numbers painted on the flight decks and island structures. I would say that they are mostly about the same size with the exception of the Enterprise which has a smaller area to paint the numbers on the island. All modern US carriers' numbers are outlined in lights which are illuminated at sundown while at anchor or moored. Some US DDGs have their hull numbers painted in a subdued scheme while others are painted in the traditional way. Why some are and some are not, I don't know.

Wow, didn't we have this thread 4-5 weeks ago? <g>

If memory serves, the smallest post war (i.e. "bright" with drop shading) size is 60" up to DDs.  Then DD's carry 72" tall on the bow, 24" on the stern; other ship classes get proportionally larger.

Durign the war, IIRC, numbers were to be no more than 24" tall, when carried at all.  (The 6" weld marks at the corners to outline the numbers could be retained as "bright" size, though.)

Sorry I didn't see the previous thread.

The ship I'm building is an AF, so sounds like they might larger than a DD. In the photo I have the draft marks at the bow are just visible, I'm going to try and scale from that.

Thanks to all for your input.