U-Boot VII C - brand new edition!

In August 1936, U-27, the first of the 10 medium-sized type VII U-boats displacing 500 tons and characterized by the placement of the stern (fifth) torpedo tube on the upper, external deck, was commissioned into the newly created U-Bootwaffe (The “Saltzwedel” Flotilla). It was not a very successful design and already in 1938 a new one was worked out, designated Type VIIB. The stern torpedo tube was mounted inside the pressure hull, the submersion system was improved and the diesels were equipped with superchargers that increased their power. The displacement rose to 517 tons. The modernized type of U-boats that had been commissioned into the “Wegener” Flotilla since 1938 met all the requirements and was highly appraised. Also the first combat experiences after the break out of the World War II confirmed its combat effectiveness. By August 1941, 23 units had been built and commissioned. The U-boat designers, however, were required to introduce yet another alterations to the newly built submarines. These were:
- The change of radio communication equipment, which involved extending the radio room by 60 cm (1 frame) and as a result lengthened the entire hull as well as the conning tower by 30 cm,
- The change of the submersion system by adding starboard and port pressure-tight crash-diving tanks, thus increasing stability (especially in heavy seas) and reducing the time needed to submerge,
- Increase in range by the enlargement of the internal fuel tank no. 1 from 32.5 m³ (type VIIB) to 37.5 m³,
- The replacement of one of the two electric-powered Krupp air compressors (starboard) by the crankless diesel driven Junkers air compressor of higher efficiency thus reducing the battery consumption.
- Due to the high consumption of the engine oil by the diesels, the ship was equipped with an oil purifying plant, so the oil could be reused.
- Protection against corrosion by galvanizing and sacrificial zinc anodes of the mechanisms and levers mounted outside of the pressure hull.
That is how a new version of the U-boat, designated VIIC, was created.