Brian
Last fall I saw another article on this, I think it was in The Yacht, that noted this trend in Europe. It seems that what one does is connect multiple engines to the electric motor with the diesels to act as generators. At low operting speed the electric motor is driven by one diesel engine (operating at an optimum RPM for efficency) and the 2nd and 3d engine can be brought on line to generate more output (via the generator attached to each diesel) for the electric motor. It seems to work well on the large steel Dutch and German yachts as they can otain some excellent results (extended range) at hull speeds yet still have a semi-displacement speed capability. The propeller is typically controllable pitch which enhances efficiency through a range of vessel speeds.
One note that I do remember is that in larger boats the regs (driven by insurance companies and charter rules) require a trained engineer to operate the diesel electric system.
Now, I am not sure how this could be applied to a 50'-60' Hatteras with twin props. But it is indeed an interesting puzzle. More of us in the yachting community (particularly those who have made the transition from power to sail) are concerened with being a bit more green than just saving dollars associate with fuel mpg. No, I am not advoacting to go the trawler route as the styling of these boats is usually awful....nothing like a classic Hatt MY (The wife is quite younger than I says she will only consider this in 20 years).
The vintage Hatteras MYs are wonderful boats and would benefit from new applications of technology.
DWM
