It is posable, 16 star ensign’s would have been a stock item at the navy yards. They have been in use since 1798, the establishment of the US Navy and the period during the US being of sixteen States. The oldest 16 star boat ensign in the collection of the Navy, it is dated to 1861, it has a star pattern 4-4-4-4 and 13 stripes but there are paintings dating to 1801 that depict 16 star & 16 striped flag with a square star pattern, 15 stars around the edge of the canton and a center star.

If you can find on the reverse of the header a number 7 and the navy yard stamp you have a winner even if you can’t connect it to the Cumberland.

You might try the textile folks at the Smithsonian or contact the Naval History Museum for guidance on getting this flag dated. Have pictures and what you know about the flag at the ready to be sent to them. If it is original, the star pattern is very rare.

Have a Happy Thanksgiving,
Tom Martin