[PSUBS-MAILIST] Speculation...

Well, obviously a sub needs to be heavy, in the sense of a traditional sub. But there are high performance submersibles that don't cling to that way of thinking. I'm thinking small, and light enough to be trailered by the average vehicle. The problem comes in with ballast in suh a light hull, as you noted, and if that could be solved, it might be possible to make submarines at a sane price that anyone could use. There are some great new materials out there, if we can only find a way to achieve neutral buoyancy while using them.