The windmill has been around for a long time. It has been given linkage and harnessed to grinding mills for, what, centuries? How is it nobody ever mounted one on a ship to spin a propeller? So equipped, wind direction would no longer be an issue, all you would need to do is point the blades into the wind, magnify the speed of the propeller with some kind of cog-based transmission, and away you zip to wherever you wanna go.
The only explanation I can think of is the surface area of wind that you can harness is reduced from the gazillion sails on the larger ships. But with only one or two windmill masts and a fraction of the rigging you’d give up a lot of weight in return. Was the propeller so complicated that it couldn’t be invented yet? Or am I missing something that goes beyond a pretty major hull design change?
Newton explained it: “For every action, there is an equal and opposite reaction.”
In other words, if you mount a fan pushing air toward the sail, it also will push the boat in the opposite direction (think of the propeller in an airboat – it’s facing backwards, but the boat goes forwards). The opposite push will pretty much cancel out any advantage you get from running the fan.
You could use a propeller like in an airboat, but I suspect that’s less efficient that an underwater prop.
You big silly, that only applies if the mechanism that produces the wind is mounted on the boat–If an external source of wind didn’t work then sailboats would pretty much stay in the harbor. I could always lock my windmill and use it as a sail, right?
Many ocean going sailboats use windmills to generate electricity to recharge the boat’s batteries. They have some drawbacks. The wind drag, unless the boat is going downwind, slows the boat a bit. They’re noisy. They have to be tied down in a big blow so they won’t self-destruct.
I’ll leave the rest of this for somebody who knows the technical stuff. I have opinions about the workability of your idea, but nothing to back them up.
Exactly. And since that is what the OP asked, it applies here.
Ultimately, any air being pushed by a boat-mounted windmill or propeller toward the sail will also cause the boat to be pushed in the opposite direction. The push would pretty much negate the extra wind being produced.
Again, look at an airboat. It’s pushing the air behind it, yet it goes forward. If you put a sail behind the airboat, it just isn’t going to go backwards – the direction the wind is blowing.
In theory, you could use a big propellor on shore or on another boat to create wind to push your own boat (though distance would weaken it rapidly). But once the wind mechanism is put aboard, it isn’t much use for sails.
Here is some more interesting discussion of wind turbine boats and autogyro boats (note that autogyro boats do not have a linkage between the turbine and an underwater propeller, but instead use the autogyo priciple in place of a sail). They have some evidence (disputed) that such a wind turbine powered boat crossed the Atlantic in 1870.
I’m not reading it that way. When the OP says “How is it nobody ever mounted [a windmill] on a ship to spin a propeller?”, I see it as a windmill that sticks up, with a mechanical linkage to turn an underwater propeller. No sails, and no prop pointing at sails.
In other words, I see a windmill that is free to turn in any direction; like the ones used to generate power. They can have “propeller” blades or vertical elliptoid blades. There is a shaft that goes from the windmill head down to a transmission which turns the shaft that turns the screw which is in the usual position under the boat.
Theoretically, I don’t see why it wouldn’t work. (Didn’t they use the idea in Waterworld?) But there seems to be an awful lot of wasted energy in the transmissions. Why not just have a sail?
You might notice that they use a hydraulic system to transmit the energy down to the prop; much more efficient and easy to build than a mechanical transmission.
I think mainly so that, as one of the links above notes, you can sail directly into the wind.
That is a cool concept – but sailing downwind would be interesting – the faster you go, the less power gets to the propeller. At some point, sailing downwind you’d want to raise the prop out of the water, lock the windmill blades and use the windmill as a sail!
I wonder what kind of speed that “Revolution” is capable of . . .
you can never get the same amount of power from the screw as you “harvest” from the windmill. While a system like that might be somewhat beneficial for sideways “tacking” it would not allow forward motion or even “tacking” against the wind as traditional sailboats need to be able to do.
In pretty much all cases, there is much greater efficiency with a standard sail and an experienced sailor.
Apparently this has been used in home-built toys (in The Amateur Scientist column, if I recall.)
But it’s extremely inefficient.
I know! First let’s replace the windmill with a solid-blade propellor like the ones in those big wind-power generators.
Then, rather than spinning the propellor, lets strip off all but one blade, connect that blade directly to the hull, so the hull becomes the “propellor hub.”
Then lets take the small underwater propellor and do the same. Strip off all but one blade and mount that blade so it sticks out of the center of the hull underwater.
And now, rather than having a spinning device, instead our “Single Blade Wind Powered Watercraft” or SPWPW can move at high speed diagonally across the water. Rather than spinning at high speed in a circle, the “blades” still move “tangentially” without ever having to spin. But after awhile you’d end up far sideways from where you’d want to go.
So lets set things up so the “blade” can flap around to the other side, reversing the sideways motion of the ship. Eventually you’d end up back where you’d started in the horizontal direction, but you’d have progressed far into the wind. (Rather than having a rotating windmill, the whole ship moves slowly back and forth, reversing direction every few minutes while making headway into the wind.)
I wonder if I could get a patent on this SPWPW machine. People wouldn’t even see it as a “machine,” since there are no rotating shafts or gear drives. All the impedance-matching gear mechanisms are blended into a single shape. It’s almost disturbingly organic. Or like something created by an alien mind.
I believe Jacque Cousteau developed and used a ship that used such a means of propelling his ship. It had what looked like a mast in the center of the ship. The mast was shaped somewhat like the wing of a plane. I have no idea how it worked and cannot find any information with a google search.
I recall seeing once a toy which would sail directly into the wind. The device had no moving parts, or rather the whole thing was one single moving part. It consisted of a long shaft with a wind propeller at one end, a water propeller at the other, and a float in between. In still air, it would float with the wind end pointing up, but a wind would tip it over and spin the whole shaft, such that the water propeller would draw it into the wind.
I remember this. Wind passed over the vertical “wing” creating a sort of horizontal lift. The wing could be rotated so a breeze from the side would effectively “lift” the boat forward. Winds from the front or back could be used but the boat would lean a bit. Forgot about that one. As I recall J.C. wasn’t impressed with the performance.