Okay, the pictures are of Otto Kretschmer's U-99 (VIIB) at drydock in Lorient in late 1940, so you'll need to use them as a guide rather than gospel for a VIIC, the main external visual difference between the VIIB and C being altered positioning of the external ventillation ducting, so it should serve as a good guide, technically, the tanks were different on the two, with an additional small buoyancy tank added to the main tank array, but externally things looked no different on the tanks. The schematics were tricky to scan, as they were on a tightly folded page, although you can determine many rib positions from them all the same. There is good reference for rippling detail on the last picture, which I can get to you at a higher resolution if you need it.
Try not to get glue on the carpet:rotfl:
Chock