Which class?
There is a lot of info, plus lots of pics, on
www.dutchsubmarines.com, I will scan the few drawings I have for the O19 and O21 classes. O16 and the K.XIV class are generally very similar, externally they differ mainly in dimensions (just a matter of a few feet in length etc.) Apart from the steady increase in the percentage of welding (which allowed the safe diving depth to be increased from 80m for K.XIV and O16 to 100m in O19 and O21 classes) the main differences were in equipment, such as the change from 8-cylinder four-stroke MAN engines in K.XIV and O16 to 7-cylinder two-stroke Sulzers in the O19 and O21 classes- but that is not something simmers would notice!