One focus of the second day of this event has been energy harvesting
. Exhibitors showed photovoltaics for boats including the very bendable sheet from Ever Energy of Taiwan using polysilicon. However two of the best presentations primarily concerned small boat propellers going backwards when the craft is under sail. In fact Milper Propeller Tech of Turkey had separate propellers that face forwards to generate electricity while under sail and turn and sheath when not needed.
They can produce over one kilowatt or, when moored in a tidestream, hundreds of watts. Generally at least 5 knots of water speed is needed by reverse propellers and their shape has to be very different.
Icelandic New Energy described regenerative propulsion in larger sailing boats where the power is also used for hotel facilities while under sail. He even dreams of making extra power to propel on-shore electric cars but we are not convinced about that. However, a zero emission sailing boat with electric drive and facilities is certainly proving possible. Inventor Joso Perkivic also had harvesting propellers for effiency but in an exceptionally lightweight 40 foot sailing boat with solar.
Speakers acknowledged that other options are becoming available such as solar sails, kite and wave energy but they want to keep things simple to start.