There's been lots of talk about electric boats recently, but few examples are actually out on the market. So far, the battery technology for large-scale applications seems to us to be a significant environmental consideration. I suspect that the carbon footprint of a big lithium-ion battery bank might totally negate the energy savings of the electric engine.
Then, on September 28th 2011, a company called BionX introduced its own electric boat. There is some very interesting thinking behind it, but the size and scale is in the dinghy range, not the cruiser range.