Sci-Fi Prisoners Build a Boat: Windmill and Propeller Construction Tips

[Danger]

I didn't see this mentioned. Maybe a few ideas are found.

Here are some Google hits

Thanks for the links, Ivan. Well, the last one. I don't feel like running that first one through my German dictionary, and the second one looks like someone took a charcoal pencil to my monitor. The 3rd one is pretty cool, though. I'd forgotten all about that thing, since the only time I saw anything about it was in some kids' book that I had back in the 60's. The feature involved building a model boat with sewing-thread spools wound up with rubber bands. I don't think that there was an explanation of why the damned thing moved.

 

[serge]

wrong. you CAN go directly up the wind. This is because the boat stands at the interface btw water and air.
the max speed of the boat will be s=w.e/(1-e), where w is the wind speed and e is the efficiency of the system (windmill+water propeller)
So if e=80% you go 3 times the wind speed and directly up to it ! This is simple to calculate (equal wind and water forces, and energy)
In that way, if the task is to go upwind, the windmill is MORE efficient than a sail !

 

[Peter A. Sharp]

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 slower boats such as fishing boats. A few have been built and sailed, and they worked as expected. An interesting approach would be to use a vertical axis Giromill so as to keep the center of pressure low, and to keep the blades outboard of the ship. For higher speeds, the vertical blades could be used as sails.