The doubled-hulled boats were to be 69.50 m (228 ft 0 in) long overall with a beam of 6.30 m (20 ft 8 in) and a draft of 3.79 m (12 ft 5 in). The Austrian specifications called for two shafts with twin diesel engines (2,300 metric horsepower, 2,269 bhp, 1,692 kW total) for surface running at up to 17 knots (31 km/h; 20 mph), and twin electric motors (1,240 PS, 1,223 shp, 912 kW total) for a maximum of 11 knots (20 km/h; 13 mph) when submerged.[3]