Sea-Sleds: The Hickman Sea-Sled is essentially what you would get if you sliced a vee bottom hull down the middle, and swapped the sides. The bottom starts out steep at the bow and flattens toward the stern. This shape generates an impressive amount of lift, and reaches good speeds with relatively low power. However, I read one account of sea-trials in the military version which said it was about the hardest ride imaginable and very wet. Flettner ships use cylindrical sails which generate lift at right angles to the wind direction. For this they must rotate, and the rotation is induced by a small motor, so they are not a fully wind powered craft, and cannot sail directly upwind. A vertical axis (egg-beater) wind turbine would result in a boat which could sail on all points. They are not as efficient as the propeller type. Propeller turbines: One aspect not mentioned on propeller driven turbines is that not only do they sail directly upwind but that is the fastest point of "sail" for them. Just like any sail, they operate on apparent wind so you can expect them to be dead slow directly down wind. In fact the most effective way to sail one down wind would be to reach and keep the apparent wind ahead of the beam. On an easily driven cat hull this should work well just as it does with conventional sails. So once you have a boat the goes directly upwind but has to be tacked down wind, how much real progress has been made? Also, I find an esthetic pleasure in sailing which I'm pretty sure would disappear on a wind turbine driven craft. Hybrid diesel electric: Hybrid cars give great economy because cars spend a lot of time idling or using very little power as we inch along in traffic. Gas engines are not efficient at low throttle openings due to pumping losses (The throttle restricts the flow). Diesels don't have throttles so use much less fuel at idle, accounting for most of the economy advantage of a diesel. The rest comes from the fact that a liter of diesel contains more energy than a liter of gasoline. In boat use, we spend much less time at idle, and generally cruise at a steady speed. I can't see how converting diesel power to electricity and back to mechanical power can possibly equal a diesel with a big reduction ratio driving a large diameter prop. That said, there are some advantages: 1. You can use one generator to power two screws, and use a second as backup or when extra speed is needed. 2. Electric motors are very reliable and will likley last longer than a reduction gear. Main disavantage? Cost. See hybrid cars. Solar powered boats. I have solar cells on my sailboat and they generate enough power to keep the beer cold and the autopilot running. That is enough for me<grin>. The wind and a (small) diesel do the rest just fine. By the way, for the cynics among us, see HYPERLINK "http://www.aviadesign.com/SexStatus.htm"http://www.aviadesign.com/SexStatus .htm Kind Regards, Grahame Shannon 2101 Philip Avenue North Vancouver, BC V7P 2W5 No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.503 / Virus Database: 269.17.4/1188 - Release Date: 12/17/2007 2:13 PM