Ian
Thanks for posting your boats design specs, 3-D rendering and profiles. This will be quite project.
I concur with Carsten that you are probably underpowered.
I have a couple of questions for you?
Looking at the boat shape, my guess is that the asymmetry of the hull caused by the sail will cause a significant pitching moment when the boat is fully submerged that will be more pronounced at higher speeds, i.e., as you go faster, the bow of the boat will want want to pitch up. I do not see any stern horizontal control surfaces. How are you going to null out this moment to be able to dynamically trim the boat?
It is obvious that you are trying to minimize drag by adopting a tear drop shaped hull. Looking at the profile, it looks like the hull length to diameter ratio is around 4. A length to diameter ratio around 6 yields the minimum total drag for a streamlined shape like this with values as high as 9 not increasing the drag significantly. Why use 4 when you could get more speed for the same horsepower with a value of 6? See "Some Aspects of Submarine Design Part 2. Shape of a Submarine 2026" By Prop. P.N. Joubert, Report # DSTO-TR-1920. Reference Figure 1, Drag components for constant volume form.
www.dsto.defence.gov.au/publications/4897/DSTO-TR-1920.pdf. Look at the profile for the Soviet Lira ( Alfa Class ) boat
www.fas.org/man/dod-101/sys/ship/row/rus/705.htm. At the time of her sea trials in 1972, she was the fastest sub in the world at 44.7 knots and still is to my knowledge. She was noisy but fast. Her length to diameter ratio is closer to 8.5.
With the novelty of using a concrete pressure hull for such a large boat, this will be a very interesting boat to follow. Please take lots of pics during the build. Best wishes.
Cliff