WINDMILL POWER
Someone was thinking outside of the box on this one. The 36-foot catamaran, Revelation II, is powered by three 20-foot long carbon fiber propellers on a 30-foot rotating mast. The windmill transmits power to a 6 blade propeller underwater, with the net result that the boat can make way even directly into the wind. Right now, you are either astonished, thinking "Why didn't we think of that before?" or your head is spinning with reasons why these boats are not currently plying the seas in great numbers. For instance, how well could such a thing possibly go into the wind if wind and water drag are offset by the forward propulsion generated? Or "who photo-shopped that windmill onto that catamaran?" for the real cynics. But it seems like there is evidence that the wind turbine concept really functions, and even some rather grainy video proof. If you want to evaluate some examples of the math for the proposition yourself. -- Read (and view) on:
http://www.treehugger.com/files/2007/02/windmill_sailbo.php

Old news. This was already done in the future, er, past, umm...

WATERWORLD! What a great movie.... <img src="http://www.catsailor.com/forums/images/graemlins/crazy.gif" alt="" />

Man, there was a looooong discussion on sailing anarchy about this kind of technology and if it was even possible (although it had been long-since proven).

Is the windmill driving a screw directly, or through an electric motor? It seems to me that if it is an electric drive, direction related to the wind is, almost, irrelevant.

Funny that this type of boats best point of "sail" would probably be straight upwind <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />
Dead downwind on the other hand, that would really "suck"

Oh crap, here we go again. Mechanically you can still go into the wind because the circular blades are drawing their power when they are at angles to the breeze. Since it's spinning horizontally, it always has some part of it at an angle to the breeze. Propellers (i.e. windmills) draw or spend their power directly into the breeze. I've seen video of a guy in a johnboat with a large propeller mechanically linked to a prop 'sailing' straight upwind.

The thing that got the Anarchy crowd going was whether or not you could exceed windspeed downwind with such an arrangement. It's been done and sustained on land before but I imagine the resistance involved with getting a vessel through the water would quickly bring you back down to sub wind speed after you bore away from a reach.

In Waterworld all it did has turn a winch to pull him off the bottom, DIDN'T sail the boat.

Doug

Oh gosh, ruin the fun. But...

Still a mast based windmill type thingy driving mechanical gear. I'm sure the Mariner could rig that to a prop if he wanted. He was smart that way.

But if you're driving a screw with it I don't really consider that "sailing" the boat in the traditional sense anyway. Wind power, yes, sailing, no.

I can't even envision what Cousteau was dreaming about there.

However, linked in that article is a rather strange and surprising article about the Flettner Ship Flettner Ship. It gives a whole new meaning to "rotating mast".

The wind speed is not a barrier, either with sails or windmills.

Both power systems take energy from the wind so that the boat can use it to overcome drag and increase speed. There is no theoretical limit to the quantity of energy that can be drawn, so there is no theoretical limit to speed.

The sail / windmill sizes are limited by engineering problems mostly associated to the weight increment vis-a-vis energy and drag increments. This should cap the speed for a given boat size. But it is only an engineering problem. As sails/windmills are built lighter, speeds will increase.

Don't know how new it is, Herrschoff built one in the 1890's that did the same thing...

There was a guy out of the miami yacht club who built one of these on a H16 platform. I saw it out sailing(?) directly into the wind, very, very, very slowly. Believe me it is much faster to tack

Unless you have a set-up like the boat in the first post (essentially a modern windmill generator), mechanical losses will eat up a lot of power to the point that it can't make headway against the wind/water drag.

This whole thing reminds me the ramblings of a man I meet in a marina . His scheme involved a wind generator and an electric troll trolling motor. He was looking for an old cat to mount it on. He had originally had it on a dinghy but some thing about hiking under rapidly spinning blades to keep it upright in heavy air made him think about a cat.

That scenario could provoke all sorts of thoughts.