Inerlocking USN Plate - from where?

[Carter NY]

Interlocking USN with Anchor. This was found in the water off of an old dock site. Any ideas on how this was used or what time period it may be from? It is a little over 2" across and is made of brass. The back is hollow and appears to have been attached to a lead backing.

 

[diggummup]

Here is another one found by rocky raccoon- http://www.treasurenet.com/forums/what/283405-belt-plate.html Yours is a much better example. What's the back look like?

Silver Service Salvaged from the Battleship <i>U.S.S. Arizona</i> - Cowan's Auctions

Same logo but much smaller than the examples posted by you and rocky.