From the web:

"Hybrid Power Boats
With the rising cost of fuel and concern for our environment, it was only a
matter of time before we saw the appearance of a hybrid power boat, you
know, the nautical version of the hybrid car. STEYR MOTORS and Frauscher
Bootswerk, both Austrian companies, have collaborated on a new venture.
STEYR MOTORS, the manufacturer of light-weight diesel motors, and Frauscher
Bootwerks, the manufacturer of 80 years worth of boats and combustion
engines, have come up with a hybrid boat. This new diesel/electric vessel
will be introduced to the public in Dusseldorf, Germany in January of 2008
at the Boot Dusseldorf show. Somehow this new system reminds this old seadog
a lot the old German "U" boat (submarine) propulsion system of the 1930's
and 40's. I can't wait to see the results of the sea trials. Stay tuned!"