According to the German law you do have two options to register your boat, while both options requesting the name of the boat and its port of registry to be shown on the transom.
You may contact the BSH (German authority drafting one of the two registry options). More details to be found under http://www.bsh.de/en/Application_for...cate/index.jsp
the sailing clubs in the city bring the port of registry.
You may checkout yacht forum (http://yacht.de/forum.html
) and post a request. For sure type and name shall be mentioned.
BTW: what is the name, the type and the port of registry you're looking up?