Gene,
By definition, it would still be a submersible as you have to come to the surface to replenish atmosphere and batteries. The German and Swede AIP military subs are near submarine.
R/Jay
Respectfully,
Jay K. Jeffries
Andros Is., Bahamas
It is the mark of an educated mind to be able to entertain a thought without accepting it.
- Aristotle
This thread is very interesting! One thing you give up with a concrete hull is transportability. I can pull a K350 with my F250 pickup.... not so with a concrete sub. On the other hand, a concrete submarine would be a submarine and not a submersible.