A boat registration number is required in Germany when a recreational boat is operated on inland waterways or sea waterways and no flag certificate is available. In this case, the identification is provided by an official registration number from the respective Waterways and Shipping Administration.
The legal basis includes, among others, the Inland Waterways Ordinance (BinSchStrO) and the Sea Waterways Ordinance (SeeSchStrO). The registration number must be clearly, permanently, and visibly affixed.
