Since the field of submersible design is still wide open to new ideas and concepts the designer has a fairly wide range of opportunities to sharpen the designs that others have developed previously. On the other hand there is a lot of existing technology that is proven and should be considered by the designer. The designer should have in mind the end-use of the boat and what it is he is asking the design to do. In my case it was just a toy to play with and a way to enjoy the mechanics of submarine operation. Another designer may wish to take passengers, or to build the boats to sell, or just to have a one atmosphere approach to underwater observation.
All uses are legitimate as long as they justify the effort.
Among the most basic design questions would be hull shape, power, ballast tank placement, window geometries, and life support. It is my desire to address some or all of these areas for those interested. The first area that I would like to cover is hull shape. The geometry of the pressure hull is of utmost importance. When I attempted to build my first submarine as a teenager back in my home town, my hull structure was elegant but dangerous.