It took the boat 3-5 hours to re-charge the batteries with the Schnorchel once every 2-3 days if travelling at moderate 4-8 knots and was thus much less in danger from aircraft which sank about 56% of all U-boats lost in the war. Also they had hydraulic torpedo reload system that enabled the commander to reload all 6 tubes in something like 10 minutes which was even less than it took to reload one tube on the VIIC normally. not carried on "Milch Cow" Tanker and supply u-boats Can use Magnetic or Contact Exploder Ballspiel was a gunnery radar for U-boats. Like most German radars at the end of the war, it was a development of Berlin. It had a range of 25km, but for practical gunnery only 8km was used. It had an azimuth accuracy of about 1 degree and a range accuracy of 500 meters. It is known that Ballspiel was used in active service, but there are no data about its effectiveness. Fitted After 1942 Fitted after September 1943 This new construction method could have pushed construction speeds below half a year per vessel, but in reality all the assembled U-boats were plagued with severe quality problems that required extensive post-production work to fix. The blame lay as much with the cutting-edge technology as with Albert Speer's insistence that the sections be made by inland companies, even though these had little experience in naval construction. It would have made more sense to concentrate all construction at the shipyards, where the expertise was available to build sophisticated vessels. The extent of the industrial fiasco can be gauged by the fact that out of 118 assembled XXIs, only four were rated fit for combat before the war ended in Europe. 1,619 # full submerged speed of 18 knots for 1.5 hours # submerged speed of 12-14 knots for 10 hours # silent submerged speed of 5 knots for 60 hours 15,500 16 17 919 58-60