sentences:  The propulsion system was improved with the adoption of water-tube boilers and reorganized to incorporate a third propeller shaft, which became standard for German capital ships.The navy had concerns about the reliability of the water-tube Thornycroft boilers, so the first vessel, , was completed with just four of the new types, with the remaining eight being older fire-tube boilers.After the first vessel was begun, the next member of the class was authorized for the 1896/1897 program; during the intervening two years, consideration was given to re-designing the second ship to match foreign developments, most significantly the adoption of guns like those on the British .