"there's no such thing as a theoretical max speed. If you have enough power, you can always go faster."
There is always a limit at some point.
I guess in this case the bottleneck will become the structural integrity in high temperature/high pressure conditions.
If you provide progressively higher power and manage to keep the boat stable and in one piece (vibration, ressonance, etc.), the ultimate limit should be when the hull colapses and burns (or vice versa) due to the difficulty to dissipate the heat caused by hull-water friction. It shoud happen at a few hundred knots speed.
If this problem is solved, maybe with ceramic foils, about the same thing will happen at a higher speed but with hull and rig friction with air. I believe this is the actual limit for a space shuttle. Now we are talking a few thousand knots.
