I suspect that would be worse. Neither generators nor electric motors are fully efficient, and they too are not immune to mechanical losses.
Not immune, just more efficient than mechnical transmissions.
I’m not sure thats the case. In general, I’d be inclined to say the opposite (though I could be wrong). And before somebody brings up diesel electric locomotives keep in mind that there are other reasons they do that and for a locomotive engine weight really isnt an issue.
I see no limitation in basic physics. The real problem with the design might be downwind since as you go faster your wind turbine loses power. As you go upwind it gains power and only water viscosity and general frictional losses limit your speed. And without a centerboard, you will have less friction.
Been done and well documented with a wind powered land vehicle. Google “DDWFTTW”. (Directly Down Wind, Faster Than The Wind) They were working on Directly Up Wind mods when last I checked on progress.
ETA, The basic trick is that you can extract the energy from the wind if you reduce the speed of the air relative to the ground. There is no requirement that you be moving slower than the wind to do that. You can take the “input” air from in front of the vehicle, and leave the slowed down air behind it.
Thats a much simpler and makes sense way of looking at it from a general principle of physics kind of way. Good work there.
True. The mechanical losses in a generator+motor system would probably be smaller than.in a purely mechanical one, but that’s a small win when compared against the losses introduced by the inefficiency of conversion from wind to electricity and again from electricity back to mechanical force.
Ok, this is a scenario I’ve been thinking about:
Imagine a very large boat facing into the wind, that has no sails and is sufficiently aerodynamic that the effect of wind on that hull is negligible. On top of this boat is a very large swimming pool. Inside the swimming pool are two conventional bilaterally symmetric sailboats, which are tethered to a frictionless rail along the back of the swimming pool by cables. The rail and cables are set up so that when the cables are taught, the sailboats are at a constant distance from the back of the pool no matter where there are to the left or right (the anchor end of the cables slides along the rail to allow this).
On command, the two sailboats beat into the wind in a symmetric way – the boats start out next to each other at the centre back of the swimming pool, the right one moves to the right, the left one moves to the left, and they tack at the same time in opposite directions over and over again.
When the sailboats travel far enough forward in the swimming pool that the cables get taught, will the tacking sailboats pull the larger boat directly into the wind (hence creating a ship that can sail directly into the wind without any energy-conversion apparatus)?
Not sure. Which direction is the treadmill running?
In all seriousness, it sounds like you’re describing something analogous to a propeller system, only using sails, fluids and cables.
I’d wondered about that, but it seems hard to believe that the two sailboats could be used to push off against something while they’re so free to move with the wind, unless the mechanism was capturing the force used by the sailboat crews to tack somehow.
The other possibility is that the beating into the wind causes a compensating force in the water of the swimming pool that would cancel the tug from the sailboats. I don’t really know enough about the physics of how sailboats beat into the wind to make a sure claim of rightness/wrongness here.
The basic misconception is that windmills provide something for the wind to push against, like primitive sails. Airfoils create lift by separating air into high and low pressure areas opposing each other. Even symmetrical airfoils create lift by varying the angle of attack. Rotating blades and wings powering a boat make wind direction above the hull irrelevant.
These use wings that do not rotate and cannot sail directly into the wind, but must tack to move upwind:
Large scale:
I still have not found a working model like the one I described above with rotating glider wings I saw in 1981. I think it is more elegant than any others I have seen, and probably more efficient.
Saw pictures of a catamaran with a Cessna wing mounted vertically and worked just like a normal sail. Was faster than snot…
Electric motors & generators & sea water make for a very high maintenance system in small boats…
With respect, I don’t think that really is the basic misconception. The misconception is that the output seems greater than the input.
Same sort of thing happens when folks talk about biofuels and solar panels - it’s not always immediately obvious just what is the input.