Speer and the new u-boats " Speer had re-examined initial delivery estimates and promised the first type XXI in April 1944. To expedite their availability, Speer built these new submarines in a radically new fashion. His biggest gamble was to rush the submarines into production straight from the design stage, without first building a prototype.To ensure a smooth transition to the new building program Speer established a Central Board for Ship Contruction in the summer of 1943. This committee consisted of representatives from the navy and the Armaments Ministry;it was headed by Otto Merker, whose previous experience was in the automobile industry. To reduce the amount of time and the number of workers required to build the U-boats, Merker proposed bulding the new submarines in prefabricated sections to be fitted together according to assembly-line procedures. Naval engineers concluded that building the Type XXI in eight sections would cut construction time from at least twenty-two months to as little as five to nine months.In addition, early estimates revealed that sectional construction would reduce slip time by 50 percent. Industry throughout the Reich produced submarine engines and accessories, and thirty-two inland factories built the prefabricated sections.From these factories the sections, weighing up to 150 tons, proceeded via inland waterways to eleven fitting-out yards near the coast. Finally, the completed sections went to three nearby shipyards- in Danzig, Bremen,and Hamburg- for assembly.Dönitz placed orders for 170 type XXI and 140 type XXIII U-boats in the fall of 1943. Many delays resulted from simple poor planning. The worst example was rushing the submarines into production.Inexperience with sectional construction also caused serious problems. The tolerance for fitting sections together ( initially plus or minus two millimeters for sections seven meter high and six meters wide ) was rarely met, which meant that there was a good bit of shuffling sections around in hopes of finding a better match. Section ends often had to be stretched, shrunk, or patched to obtain a fit.Another problem was that the type XXI submarines incorporated hydraulic power for all control systems and the periscope, antiaircraft armament, and torpedo hatches. But the Germans were relatively inexperienced with hydraulic design, and defects in the system led to chronic delays. On several occasions shortages of various components, such as batteries, periscopes, or electric motors, usually caused by Allied bombing, postponed production. many sections arrived at the assembly yards with essential components missing. Further, although Hitler had assured Dönitz on 24 September 1943 and again on 26 February 1944 that he would support any measures to accelerate production of the new U-boats, in April 1944 he suddenly granted fighter production top priority. This confusion in armaments production also contributed to delays. Hitler, Dönitz and the Baltic Sea by Howard Grier
..my belief is when you are in a hurry, is when you make the most mistakes ... .....we have modern, high tech computer software for engineers that is specifically designed for engineering and design work....the engineers design, calculate, fit, etc everything on the computer before production......yet, they usually still make mistakes--in 2020!! --and this is on stuff that is very simple--nothing, nothing compared to a sub .... so mistakes rushing a huge, complicated sub into production is very much expected ..it's amazing they accomplished what they did..it's impressive --especially considering the bombing/etc
Hmmm... Re. the last paragraph in K-P's post: I don't see how increasing fighter production would interfere with submarine production. Subs are made out of steel and aircraft out of aluminum and some other metals. Their construction should be in different plants and yards. The problems in construction of these U-boats was not only of rushed schedules, it also was that the labor was often foreign workers-AKA slave labor-who had no great desire for a nazi victory.
Cannot answer directly as it is from the book. However, I always thought Hitler wanted vengeance weapons first of all such as V1-V3 and thus bombers were more important than fighters,too. which was weird as the Reich was being bombed to kingdom come and Hitler wanted to bomb London primarily.
From what I remember...They hydraulic system was taken directly from the Type XVIII submarine, precursor to the Type XXI, to speed the design process, but was not exactly a good fit. Further, the hydraulic piping was fitted outside the pressure hull, where it was more susceptible to damage. They hydraulic lines were reworked and placed inside the pressure hull on later XXIs. Addition - other U-Boat types were fitted with hydraulic systems - namely the Type IX & Type X classes. Just with the Type XXI, the hydraulics were used to operate more equipment. When the US examined the Type XXI after the war, the felt the system was overly complicated. This is not inexperience, but meeting different design parameters.
