Boat propulsion using windmill power directly

As everybody knows A windmill powered boat can sail directly into the wind that powers it.

Recently, I put up a page on my website of a simple model to demonstrate direct-into-wind sailing,

This model has more drag behind the clr than in front and weathercocks automatically to windward.

Therefore, when released at the downwind end of a pond, it automatically sails directly to the upwind shore.

I'm hoping that publishing these plans will encourage others to make similar (but not necessarily exactly the same)
models.

If two or more of these models are released at the same time, the one that reaches the upwind bank first will have demonstrated the greatest efficiency of direct into wind sailing.

Many attempts have been made to predict mathematically the best setup for this kind of craft, but no matter how good the calculations, they mean nothing unless they can be proved by practical testing.

For example, one variable that cannot be accounted for, is the random variation of the natural wind all the time in both strength and direction.

There has been some dispute recently about what is the best setup for these models; whether it is better to use many windblades with a low tip speed ratio, turning at a low speed, or to use a few blades running much faster with a high tip-speed ratio.
These are the kinds of issues that could be resolved by this sort of comparative testing.

The only "rules" that would be required in a competition between different designers with different opinions about setup, would be that the swept area of the wind-rotor disc would be the same, therefore the same amount of potential power-producing wind would be intercepted for each case.
All other parameters would be optional.

Here in Norwich, UK, we are fortunate in having a purpose built model boating lake, free to use, which would be very suitable for this kind of testing (Eaton Park).
So I'm obviously interested to hear of anyone within reach that builds a model of this sort, so that comparative tests with my own model could be made.

 

I never would have believed it but I saw that wind powered boat on youtube. It seemed to me that you were trying to build a perpetual motion machine. But hey I can't argue with success. Now I have to wonder if the same thing couldn't be applied to a wheeled vehical. pretty neat stuff.

 

There is a competition in the Netherlands for the wheeled versions.
Read about it here: http://www.sciencedaily.com/releases/2008/08/080827104702.htm

 

Pretty cool stuff. looks like it could easily be done on a hobie cat.

I toyed with the idea of a windgenerator going through battery to motor. But I have to question. at what point can we consider such a setup to actually be wind or solar powered? If it takes a week of solar or wind charging to provide an hour of propulsion, I am not sure I would call the boat solar powered. maybe we should coin a new phrase "Solar assisted". Your design is definitely pure tho. I like it.

 

Thank you.
The direct drive method is certainly interesting because many people don't believe it is even possible.
However, whilst a boat is at a mooring and the wind is still blowing. It makes sense to store up some battery power for later use.

 

would a windmill powered boat be subject to "Ground effect" like an airplane which can do a lot more when within one wingspan's height above the ground than it can when aloft? if so one would gain nothing trying to put the generator higher on a mast but would lose a lot in stability.

 

As I mentioned in the other thread. "Ground effect" is not relevant at all here. Being concerned with vertical force and we are only interested in horizontal force. A boat only moves in two dimensions, not three.

 

I think I was asking more out of curiousity if a concept I am familiar with applies at all.

The air to the windvane will be denser close to the surface of the water and therefore contains more energy, but as there are other reasons to avoid hoisting one way up on a mast, it would be irrelevant other than to get it high enough so as not to be walked into.

I am sure the difference in air density between 5 feet above the surface and 30 feet would be negligable.