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

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Discussion Overview

The discussion revolves around the construction of a windmill and propeller for a fictional boat designed by prisoners on a stone-age-like planet. Participants explore various propulsion methods, including windmills, sails, and oars, while considering the materials available to the prisoners, such as steel, wood, and car parts. The focus is on the feasibility and efficiency of these designs in a sci-fi context.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests using a windmill to power a propeller, considering its utility in narrow channels and during storms.
  • Another participant questions the practicality of a windmill, proposing that a long-boat with oars and sails would be more efficient.
  • Some participants express concerns about the complexity and potential failure of windmills, especially in adverse weather conditions.
  • There is a discussion about the potential use of car parts, such as radiator fan blades, for propeller construction.
  • Participants consider the possibility of using metal sails made from car bodies and scavenging fabric from car interiors for traditional sails.
  • One participant highlights the significant energy loss in transmission when using a windmill to drive a boat, suggesting that it may not work effectively.
  • Another proposes the idea of a catamaran or an amphibious sailboat that could utilize car wheels for beach landings.
  • There is a mention of the prisoners' willingness to work for their freedom, suggesting a muscle-powered approach as an alternative propulsion method.

Areas of Agreement / Disagreement

Participants express a range of views on the feasibility of using windmills versus traditional sailing methods. There is no consensus on the best approach, with multiple competing ideas and concerns about efficiency and practicality remaining unresolved.

Contextual Notes

Participants acknowledge limitations in the prisoners' resources, such as the absence of a press or high-temperature furnace, which may affect their ability to construct efficient designs. The discussion also reflects uncertainty about the energy output of the proposed windmill and propeller designs.

Who May Find This Useful

Writers and creators interested in sci-fi engineering concepts, as well as those exploring innovative propulsion methods in fictional contexts, may find this discussion relevant.

  • #31
Ivan Seeking said:
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.
 
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  • #32
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 !
 
  • #33
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.
 

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