From the Selene website, under "Yachts/The Selene Advantage:"
The design incorporates the fuel efficiency of a full-displacement hull. A full-displacement hull is designed to remain fully in the water throughout its entire range of speed. This requires a fraction of the horsepower that semi-displacement or planing hull requires to attain optimum speed. A full-displacement hull will be capable of maintaining speeds in the 7- to l2-knot range while burning a minimum of fuel.
Didn't look at individual model descriptions...
-Chris