A Bay os Biscay bonito fishing boat. The waterline of any boat must be defined by the seas on wich it will sail. Boats that sail the Bay of Biscay and/or the Atlantic have a different shape from those that sail in gentler seas, such as the Mediterranean. Their superstructure is also very particular, given that while fishing the catch must also be classified by sizes and introduced into the different departments that, depending on needs, are adapted on the deck.