I agree... diesel-electric power may be a good choice for cats, given their ability to plane and sustain cruise speeds with less power. Good idea for multiple gen-sets and weight distribution as well!
But when I was referring to interior space, I was thinking about accomodations, not engine room space. The wavepiercer designs probably offer the most viable solutions to this problem, but they are more expensive to produce and have some quirks in certain water conditions as I am told.
A solution may be a true cat hull with a shallow tunnel, configured in a "V" form to offset wave impact (much like a wavepiercer). Still, this design would not offer the interior volume of its displacement counterpart, but with good space utilization, could approach a viable alternative.
Just some random thoughts...
