Hi Francois:

Jeffrey LaRue, of "The Subcommittee", makes a set of photo-etch decks for the DK Models 1/48th scale Type-VIIC U-boat. They are .010" brass and are available for the main deck as well as the conning tower, you also get a housing for the loop antenna. Also the conning tower deck has them hundreds of square holes cut out for you. These decks are extremely accurate. I just went out and measured my main deck and the slots are only .035" wide. Now that is pretty small for a milling machine. Dan Kachur used to make a cast resin deck that was approximately .055" thick but now recommends the LaRue photo-etched decks. That is the reason that your hull has that drop between the bow and stern for this .055" deck. I made a .045 aluminum spacer to raise the .010" brass decks to the proper height. Most people just put the deck low and add a plastic coping around to fool the eye. If you are making the model radio controlled keep it as light as possible up top. If not she will want to roll on you during the turns.

Good Luck and Good Hunting,
Jerry Pope
Georgia U.S.A.