I wonder if it would be practically possible (as opposed to theoretically, you understand) to build a yacht (something like one of these Austal 41 catamarans) that used a modification of the Sheerwind electrical power generation system to supply principal motive and operations power? Yes, you would definitely want a diesel back-up generator and sufficient fuel stores for ~10 days max load operations. Maybe (who am I kidding, almost certainly) a battery storage system too. A fresh water desalination capability along with a grey/black water reclamation system, of course. In fact, pretty much every technology you would want in an ocean-going yacht that you can shoehorn into the available volume, just like pretty much every other ship design. The object here is to have a "fuel" system that uses less interior hull volume than the existing traditional diesel fuel design for that same model of vessel does now.
The wind generator would require a redesigned blade system, for only one major change. The captured wind would have to be routed down to the engineering spaces (the pontoons), presumably through some sort of funnel-type structure extending well above the uppermost deck area, and then exhausted well away from any working deck areas, antennas, small craft hoisting equipment and most emphatically not anywhere near the waterline (whatever the sea state). Depending on how the air ducting was laid out, it ought to be quite possible to spin up a series of smaller generators from the same given volume of air with sufficient wind velocity. From the Sheerwind site, it would appear that a boat traveling fast enough to supply about 8 knots of wind down the deck would be more than sufficient (which is a fairly normal wind state when tied up in port). A twin ducting system branching port and starboard from a mid-ships wind collection tower could supply a series of generators placed within the system essentially twice the length of the boat if the ducting was routed forward the length of the pontoons and then up again to the uppermost decking and then aft to exhaust through a parallel array of exhaust ports facing aft (and thus two decks above the main after deck).
Performance wise, I think a boat that could cruise at ~18 knots and sprint at ~30+ knots would be more than sufficient for a non-commercial/non-military vessel. This would allow for a 24-hour day cruise distance of roughly 400 nautical miles. Assuming an on-board food stores capacity for 15 days fresh and 30 days re-constituted (powdered drinks, dehydrated proteins and carbs, etc) a non-stop voyage of 20 to 30 days duration without having to budget for fuel resupply would shift yachting a good deal closer to being more of a middle class aspiration, I would think. A boat that didn't require shore-based fuel or power connections in port would be a big financial savings too.
I think I'll contact Sheerwind and Austal USA and ask them what they think.
Update #1: When considering redesign of the wind generators, do consider some recent research that appears to have some relevance to performance improvement. Excerpt: "Because wind turbines are heavily braked in order to minimize noise, the addition of this new surface would mean that they could be run at much higher speeds producing more energy while making less noise. For an average-sized wind farm, this should mean several additional megawatts worth of electricity. An investigation into how owls fly and hunt in silence has enabled researchers to develop a prototype coating for wind turbine blades that could significantly reduce the amount of noise they make. - See more at: http://newenergyandfuel.com/http:/newenergyandfuel/com/2015/06/25/owl-based-study-shows-how-to-make-silent-wind-turbines/#sthash.lPA8vcsY.dpuf".