A few years ago, I was contracted to do a viability study on an all-electric outboard motor, but nothing like this! Nautique and LTS Marine are making a true electric alternative... http://nautique.com/videos/index/100-electric-nautique/category:Ski Nautique
This is probably the best application, (I mean waterskiing), for a fast electric boat. As it is usually close to getting home for charging, and often in freshwater lakes where a silent and clean boat is the ultimate solution.
It certainly appears to be a real solution for most inland lakes. Will look forward to more stats regarding range for non-ski applications. This kind of power, for even an hour, could make electric boating a real alternative...