Like the Typ XXI , the small coastal U-Boats of the Typ XXIII were a new step in submarine design. Build as a replacement of the old Typ II , those boats were faster submerged than on the surface, caused by their powerful electric engine and hydrodynamical shaped hull. Although more than 300 boats were ordered, only few were completed and even fewer got operational (see Typ XXI ), but those few proved that they were capable to operate even with the heavy allied anti submarine warfare in the second half of the war. Two of those boats were used by the Bundesmarine after the war (U2365 , U2367 renamed to Hai and Hecht )