So all I need to do is describe the windmill boat on the river in terms of the apparent wind, which is the same as for the windmill boat on stationary water in a true wind. Correct?
I'm not clear on this. "not losing as much energy from drag" as what?
In both cases -- flowing river or stationary water plus wind -- it is the relative motion between the two sailing media (air and water) that is the source of energy for the windmill boat. If we use the frame of reference...
But then why could we not say that a windmill boat in a true wind on a stationary body of water experiences reduced drag, and is propelled by that reduced drag. That does not sound right at all. In both cases, there is an equivalent conversion of energy by the windmill. We can say that the...
If I understand you, and please forgive me if I do not, you are saying that when the boat uses its windmill, it is more efficient than when it does not -- and therefor less inefficient than when it does not.
But how does that observation differentiate between this situation of the boat on...
Let us ingore gravity in this case for the sake of simplicity. We could, for example, replicate the same relationships in a test tank with circulating water. There, gravity would not need to be considered as part of the analysis in terms of the energy transfers.
A boat with a windmill rotating a water propeller can sail directly upwind. It has been done many times, so take that as a given. (The maximum speed so far is about 0.5 times the speed of the wind. For a land yacht, the maximum speed so far is about 1.0 times the speed of the wind.)
My...
Using windmills to propel ships has been studied for a long time. The main problem is that a windmill has high drag. So in practice, the speed in any direction is typically around 0.5 times the speed of the wind. Most ships travel at higher speeds than that. So windmills would be best applied to...
A windmill boat uses a windmill to spin a water propeller. They can sail directly into the wind. So in this case, if we use the river as the frame of reference, the windmill boat is sailing normally relative to the river and sail down river faster than the river. The speed will be no more than...
Assume a windmill boat is drifting down a fast flowing river during windless conditions. It uses its relative wind to outrun the speed of the river. What is the correct way to describe this situation in terms of energy and power? Can we say that its energy is derived from the river but its power...