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

[Reb Bacchus]

My first book has made it all the way to the publisher's desk, where I'm told it will sit until I have a second. The first was a bit of cliff-hanger. I'm working very hard on the second and hope to have it finished by the end of the summer. Actually, I hope to have it done in two weeks, but it will take all summer for my wife to fix it. (If you can't write, but discover a need to write a book, I suggest you marry an English teacher.)

The books are sci-fi and the story line is about a section of a maximum-security prison that marooned on an Earth-kike planet stuck in the stone age. My creative prisoners are now building a boat to make contact with the natives. I am thinking about creating a windmill devise to power a propeller. I'm also still trying to design the ship. (it needs to be large enough to carry 100+ on a 2000 mile voyage.) Sail will provide the main propulsion, but I thought about using a windmill for special work like very narrow channels, or to maintain headway in a storm.

Now for the question, given steel, wood and welding supplies, how would you construct a such a windmill, and more important a propeller? I need to add they have a parking lot full of cars, but almost no fuel.

 

[willib]

this windmill store power in batteries?? to be used when navigating narrow channels.??

 

[arildno]

This is perhaps prosaic of me, but a long-boat propelled by oars&sails (like a Viking ship) would be a lot more efficient.

 

[deficiency4math]

i agree, windmills would just be too complicated and would have a million variables to go wrong, especially in a storm! Sails, two, three masted, depends what you want, and maybe oars or a man-powered fishtail. (make sure to get the sailing right, as I am a sailor, and i don't want to read shabby sailing! *wink*) by the way, it sounds pretty interesting, so what's the name of the book, so i can look out for it?

 

[Reb Bacchus]

Let me backtrack a little.

i agree, windmills would just be too complicated and would have a million variables to go wrong, especially in a storm! Sails, two, three masted, depends what you want, and maybe oars or a man-powered fishtail. (make sure to get the sailing right, as I am a sailor, and i don't want to read shabby sailing! *wink*) by the way, it sounds pretty interesting, so what's the name of the book, so i can look out for it?

The current working title is "Cliquing on Time." Based on what the two editors who've recommended it for publication have told me, it will probably be changed should the publisher decide to buy it.

I read a few more of the answers on other threads, and I'm blown away by the technical competence here. I found this site through google because of a thread of someone trying to use a windmill for a land vehicle. I am trying to limit the sci-fi to how they were accidentally sent a different planet. I'd like everything else to be science, or engineering. I believe that humans are almost endlessly creative, but I'm not. Thus, I've used places like this to find out if something is possible, and to get tiny thumbnails about how to do it. I've gotten help in other places on many odd topics... like how to make a windmill.

I agree that building a windmill from scratch would be impossible. But, when I was a senior in high school, my parents bought a ranch... Truly "Green Acres," but that's another story. The only source of water was a windmill and a cistern. I was always impressed with how simple that Aeromoter windmill was. We took it apart once to grease and repack the bearings.

My creative convicts only need to pull a drive shaft and rear end from one of the cars to have the "motor" part of a windmill. I think they'll be using one of the tall steel light polls for a mast. One of the inmates is a former nuclear power plant welder, and he has plenty of supplies. They also have steel from the roofs, metal buildings and security doors. What they don't have is any sort of press, or high temp furnace. Part of the reason to build the ship is to get coal so they can work metals beyond welding.

They can have plans (via their computers and textbooks) for any sort of design they need to build, but they don't necessarily understand what they are looking at.

One of the things I don't know --- hence they don't know is just how much energy would be provided by a the type of vanes they could produce. I don't know how much would be lost in transmission and how efficient a propeller they could produce. I had originally thought of having them build a Knarr (Viking merchant ship) but a yachting form suggested I consider something with an outrigger for safety. (I had hoped to use a canting keel for extra speed but it looks like that would be beyond them technically.) I'm trying to understand advice about design and ballast and the strength of wood versus ripping up a whole building to make the hull out of steel.

The problem is that all I know about propeller design and windmill vane design is that small difference create large changes in efficiency.

Bottom line, given the welder's skill, could he make an efficient windmill vane and a good propeller. If he did so, would it produce enough power to make a difference. I.E. given a 20 knot wind how fast would a 120' Viking long boat be able to head directly into the wind? If that doesn't work, I guess I'll just have to figure another way to keep them from being blown on to the rocky coast.

I do thank you for your advice, I do understand just how off the wall this sort of question is.

 

[willib]

Now for the question, given steel, wood and welding supplies, how would you construct a such a windmill, and more important a propeller? I need to add they have a parking lot full of cars, but almost no fuel

Are you sure this is fiction ??
kidding.. sort of...
for the propeller/s you could bend the radiator fan blades of some of the older cars..
how detailed do you have to get.??

 

[willib]

Hmmm, have you thought of a catamaran type boat..
ps i was typing when you posted ..which is unusual for this site..

 

[willib]

since it was fiction i did'nt think it had to actually work .. so skip the car radiator idea..ok , he has a welder , so they could bend and weld sheet steel together building up the hub with layers till it looked like a real prop..
question are these prisoners willing to work for their freedom , if so how about hooking each one up to a station where THEY power the ship , ala muscle power..when needed?

 

[hitssquad]

Boat ideas

I don't know how much would be lost in transmission

A lot. That is one reason ships use sails. I would expect that a windmill powering a driveshaft on a boat would not work at all, as opposed to working merely with low efficiency. If it does work at all, it will only be once in a long while when a strong gust comes up -- say, in the 30 mph range. So the boat would run maybe for half a minute every half hour or so, if the characters are lucky.

Another reason boats use sails is that sailboats can sail almost straight into the wind. If you do that with a windmill-driven boat, you will essentially be manufacturing energy from nothing.

The characters are going to need a strong impetus for pursuing such a backwards propulsion concept as a windmill-driven boat.

If you want a water craft that is bizarrely unique, perhaps it could be an amphibious sailboat. Sail up to a beach and keep on sailing, riding on the boat's car-wheels.

If you have cars and no fabric, perhaps metal sails could be made from the car bodies. Back in the 1980's, Japan produced a sailboat with (motorized, electronically-trimmable) metal sails. If you want to have the characters scavenge fiber material to make sails, the car seats might be good for fabric. Also, cars have carpeting and headliners (fabric on the undersides of car roofs).

A car's rack-and-pinion steering system might be usable as part of a steering system for a boat. The gearing should be changed, however, to a much more shallow steering ratio (you should make it so the wheel goes around perhaps dozens of times between the locks, as opposed to just a few times -- this makes it easier to steer a heavy vehicle like a boat).

Another idea would be to skip the windpower idea altogether and have the characters make alcohol or biodiesel to power an engine with. (If they have access to any kind of surplus food-carbohydrates, they can make alcohol -- unless there is no yeast in the air on that planet.) They could also modify their car engines to run on wood-powered steam. And finally there is also a way to run engines directly off of the fumes from gasified wood, but that might be too complicated for your prisoners to figure out.
google.com/search?q=wood+powered+truck

 

[Reb Bacchus]

Great Idea...

Are you sure this is fiction ??
kidding.. sort of...
for the propeller/s you could bend the radiator fan blades of some of the older cars..
how detailed do you have to get.??

I'm not sure why you said to skip the radiator fan idea in a later post. If nothing else it gives them a template to go from. I'm using plastic fan blades from air fans to generate trickle charges for UPS systems in the unit now, but I thought those would be too small. I'm sure they'd be able to pull a radiator fan to use as a propeller. One doesn't have to get detailed, but I wouldn't want someone who knows something about radiator fans to scoff.

These men and women have been free for a year... ever since they landed, but they can see their standard of living taking a nose dive soon.

 

[Reb Bacchus]

I'm not sure I understand...

A lot. That is one reason ships use sails. I would expect that a windmill powering a driveshaft on a boat would not work at all, as opposed to working merely with low efficiency. If it does work at all, it will only be once in a long while when a strong gust comes up -- say, in the 30 mph range. So the boat would run maybe for half a minute every half hour or so, if the characters are lucky.

Another reason boats use sails is that sailboats can sail almost straight into the wind. If you do that with a windmill-driven boat, you will essentially be manufacturing energy from nothing.

I know that someone build some large tankers or cargo ships a few years ago that had windmill assisted power. One's windmill looked like an old fashion kid's toy, the other like the windmills you see on wind farms. The idea on a ship is that the windmill rotates so that it always faces the wind, so the direction of the wind doesn't matter. I know watching our old windmill that even in a mild breeze it could rev up to, what seemed, several hundred RPM. All it powered was a sucker pump but when the wind was up it could fill that whole cistern in no time at all. I just have no idea what the horsepower of the thing was.

One of the problems I created for myself in the first book is that they are located on a peninsula with a huge tide. Think about something twice as high as the Bay of Fundy. That bay is only a couple of miles wide in several place at low tide. Given a good hull and keel, you can sail close to the wind, but trying to tack on in a narrow bay is murder. Toss in those tides... I had thought about letting them ride the tide out, beach and wait for the next tide, but that's tough too. I figured if a modern

If you want to have the characters scavenge fiber material to make sails, the car seats might be good for fabric. Also, cars have carpeting and headliners (fabric on the undersides of car roofs).

I hadn't thought about that, I just hate to tear up the cars... I hate the Mad Max view of the thing... still.

A car's rack-and-pinion steering system might be usable as part of a steering system for a boat. The gearing should be changed, however, to a much more shallow steering ratio (you should make it so the wheel goes around perhaps dozens of times between the locks, as opposed to just a few times -- this makes it easier to steer a heavy vehicle like a boat).

Great idea, I had thought of using an old fahion tiller, but this is much better.

Another idea would be to skip the windpower idea altogether and have the characters make alcohol or biodiesel to power an engine with. (If they have access to any kind of surplus food-carbohydrates, they can make alcohol -- unless there is no yeast in the air on that planet.)

They've set up a still, a very controversial project since alcohol and drugs are a major reason most folks are in prison. On yeast, I had no idea how hard it is to make yeast. Part of what I'm trying to do is to illustrate just how many common things we take for granted.

 

[Huckleberry]

I don't understand why they would want to use a windmill at all. A sail seems much simpler and more effective.

The force that moves the ship forward comes from resistance to the air. A sail catches the air and this moves the boat forward. A windmill turns and much of the air passes by it. The purpose of a windmill is to create energy for some other purpose. The prisoners would be much better off sticking that propeller in the water where it would have much more resistance and be more effective. They could create some mechanism to rotate the propeller for forward motion, and turn the propeller like a rudder for steering.

keels are nice because they help guide a boat. They are streamlined through the water and pushed less sideways by the wind. It is not necessary to have a single hull keel. A double hull is much simpler to construct and more of the boat is out of the water. This kind of boat has to displace less water and is faster and also more stable. Double hulled boats were used by uncivilized tribes for millenia. A boat doesn't even need a keel, but it would be difficult to keep it on course. Hmm, might be prone to overturning in large waves too.

A 2000mile trip is a long trip. I think water would be their biggest problem. Some method of desalinization might be necessary. The windmill idea might be useful here. IIRC there is a method using a flywheel and a thin stream of water that is evaporated. Check that out before using it. But any windmill used on a ship with a sail is inneficient. They are counter-productive because they are using the same source of energy.

 

[willib]

But any windmill used on a ship with a sail is inneficient. They are counter-productive because they are using the same source of energy.

i dissagree..think about it, some wind turbines like www.otherpower.com have 17 foot spans . three or four of these babies on a hundred foot ship might be able to power it in every direction but directly into the wind..
i am assuming these wind turbines in your story are geared , like a differential of a car, with the driveshaft entry point connected to the turbine , and the driven part connected to a shaft down to another differential driving the propeller?

 

[Reb Bacchus]

I don't understand why they would want to use a windmill at all. A sail seems much simpler and more effective.

Certainly true, most of the voyage will be under sail. However, there are two reasons for wanting something high tech but easy to do. The first is that I've done enough sailing to understand how hard it is to maneuver a ship in close quarters under sail. The will have oars, sweeps really, but if you've ever been around crew, you understand it takes a lot of practice to teach people to row together and it takes great strength if the vessel is heavily loaded.

Being able to use something like a windmill would all a boat to do thing impossible under sail.

The second is that it looks more like magic. I think it would impress the heck out of a stone age savage. It would also be harder for them to understand and duplicate.

The force that moves the ship forward comes from resistance to the air. A sail catches the air and this moves the boat forward. A windmill turns and much of the air passes by it. The purpose of a windmill is to create energy for some other purpose. The prisoners would be much better off sticking that propeller in the water where it would have much more resistance and be more effective. They could create some mechanism to rotate the propeller for forward motion, and turn the propeller like a rudder for steering.

If you have an idea for something that would generate the power to run the propeller, I'd be very interested. I agree the windmill isn't very effective, but I don't know of anything else that might work. I did think about a steam engine, but their only fuel is wood. Getting a boiler on line takes a lot of time, keeping it going takes a lot of wood. I don't see the cargo capacity for it.

Someone suggested batteries, I hadn't thought about that, they have many electric motors, that might be an option.

IIRC there is a method using a flywheel and a thin stream of water that is evaporated. Check that out before using it. But any windmill used on a ship with a sail is inefficient. They are counter-productive because they are using the same source of energy.

The voyage will take ten days to two weeks, I know because if I have to, I'll move the continents closer... ah the power!

I am very interested in trying to create drinking water. I was thinking about a solar still, but I don't know enough about that yet. I seem to recall black plastic and they do have just a little of it.

 

[Reb Bacchus]

I can do a 17' span

i dissagree..think about it, some wind turbines like www.otherpower.com have 17 foot spans . three or four of these babies on a hundred foot ship might be able to power it in every direction but directly into the wind..
i am assuming these wind turbines in your story are geared , like a differential of a car, with the driveshaft entry point connected to the turbine , and the driven part connected to a shaft down to another differential driving the propeller?

The problem is what to do with the windmill vanes when the ship is under sail? I had thought about collapsing them to a single vane and lashing that to the mast. That would take some pretty good engineering and manufacturing, so...

I'd never thought of using more than one, and then only for special situations. Thanks for the link, but why do you think you couldn't sail directly into the wind? Since the blades rotate 360 degrees, and they always face directly into the wind, I don't see why sailing into the wind would make any difference.

 

[Reb Bacchus]

i am assuming these wind turbines in your story are geared , like a differential of a car, with the driveshaft entry point connected to the turbine , and the driven part connected to a shaft down to another differential driving the propeller?

I'm planning on using the differential from a car or two to make it work... True confession, I know those things work, but I just take my car to a mechanic and say, "fix it." A fellow said I could use one to do this so I'm taking his word. He also suggested that I use the rear end of a car to make paddle wheels instead of a propeller. That remains a final option, but paddle wheels are so inefficient

 

[willib]

a solar still is simple , evaporated water condenses on the skin of the evaporator and drips into a container..
http://www.epsea.org/stills.html

 

[willib]

why do you think you couldn't sail directly into the wind? Since the blades rotate 360 degrees, and they always face directly into the wind, I don't see why sailing into the wind would make any difference.

I am not sure that would be possible ..
i don't think any sailing ship ever sails directly into the wind anyway ..you can tac close to it but never directly into it..

 

[Huckleberry]

Those windmill turbines create electricity, not a whole lot of forward momentum. Although you could possibly use a windmill to create electricity for any number of purposes. An important one might be desalinization. Sails are the way to go. Sails and windmills both used for propulsion are about useless.

Instead of rowing, having some sort of a pulley system attached to a propellor in the water would be a good way to propel the ship in addition to sails. Doesn't seem to solve any problems and requires a lot more mechanical parts.

Sailing directly into the wind would not work. The force of the wind is acting in the opposite direction of the ship. If the ship wants to move in that direction then it needs to provide the momentum to do so from another source of energy. Propellors or oars.

 

[Huckleberry]

On a long voyage like this one you might be interested in Hadley cells. Depending on the angle of the planet to the sun certain weather patterns form. I think there are 6 Hadley cells separated by latitude.
Here's a picture. http://www.newmediastudio.org/DataDiscovery/Hurr_ED_Center/Easterly_Waves/Trade_Winds/Trade_Winds.html

Some of these regions get more rain than others and have different trade winds. Merchant ships from the Brazils would often go way out of their way to the north to catch the westerlies to head for Europe. A wind is named after the direction it is blowing from.

The regions between these cells have unusual patterns too. The doldrums are at the equator. The heat causes the air to rise and there is little wind. The direct rays of the sun evaporate a lot of water which cools in the atmosphere. This area has a lot of rain.

But if you go about 30 degrees latitide north or south then you reach the division of the westerlies and the northeast trade winds. This area is called the horse latitude. It gets very little rain and is the area in the world where many of the deserts in the world are located. It is called the horse latitudes because when sailors ran out of water, the horses would be the first thing that died. I guess sailors would rather save the water for themselves and eat the horses.

 

[Reb Bacchus]

Thanks!

a solar still is simple , evaporated water condenses on the skin of the evaporator and drips into a container..
http://www.epsea.org/stills.html

I consider myself pretty good at finding stuff on the 'net. However, it's so much better when someone who knows something can recommend a site. When I began writing, I had no idea how many details like this would require research. It's the difference between knowing and knowing how.

Thanks again.

 

[Reb Bacchus]

Ahh the missing link?

Sailing directly into the wind would not work. The force of the wind is acting in the opposite direction of the ship. If the ship wants to move in that direction then it needs to provide the momentum to do so from another source of energy. Propellors or oars.

The idea here is that the windmill will, with gearing, turn the propeller shaft. Some energy will be lost in the gearing, but I don't think very much.

 

[Reb Bacchus]

Wonderful!

On a long voyage like this one you might be interested in Hadley cells. Depending on the angle of the planet to the sun certain weather patterns form. I think there are 6 Hadley cells separated by latitude.
But if you go about 30 degrees latitide north or south then you reach the division of the westerlies and the northeast trade winds. This area is called the horse latitude. It gets very little rain and is the area in the world where many of the deserts in the world are located. It is called the horse latitudes because when sailors ran out of water, the horses would be the first thing that died. I guess sailors would rather save the water for themselves and eat the horses.

Thanks for the link. I relied to this once and lost it when I spell checked, so if there is a double post forgive me.

I had planned on using trade winds, but I worried that they were caused by land mass and currents. This is the sort of detail that sci-fi readers love, and will murder you if you get wrong. I was just going to say they existed, now I'm going to have to add miles to voyage because they're going to have to sail south to pick them up. I think I may have to move the continents after all.

 

[Huckleberry]

The horse latitudes also have very little wind. Where the air in the doldrums is rising at one side of the Hadley cell it is decending on the other at the horse latitudes. The decending air warms. Warm air holds more moisture so this region gets very little precipitation. Little wind or rain, a very dangerous place for sailors. This site explains simply why this happens and how the regions shift depending on the season.

I notice it says that the reason that sailors threw the horses and cattle overboard is unclear. I would guess that the sailors couldn't eat all the animals in a short period of time. Keeping them all alive requires water that they don't want to spare. They don't know when they will have wind or rain and may be trapped in the region for some time. So they kill most of the animals and if they can't salt all the meat then they have to throw it overboard.

 

[willib]

Just because the trade winds are the way they are on this planet , does not mean that they have to behave the the same on another..

 

[Huckleberry]

True. It depends on the angle of the Earth to the Sun, the velocity of rotation and revolution of the planet. It also depends on how the water and land masses are arranged on the planet, assuming it is an Earth type planet.

Assuming the planet has an Earth-like atmosphere and is mostly covered with surface water at it's equatorial region and the planet has a similar tilt to the sun, then the trade winds over ocean regions would be similar. The velocity of rotaion and revolution would change the strength and frequency of the patterns.

 

[minger]

This is a great conversation, but I have a quick comment about the windmill thing. I think that the windmill would only work in very few instances. For me, when I'm thinking of a windmill on a boat, the first thing I think of it, well won't the wind actually push the boat back?

I mean, the blades redirect the wind giving the wind a sideways velocity as a straight forward velocity, this turns the blades. But, the majority of the force acting on the blades will be pushing them straight back. It just seems that you are trying to get more energy out of the system than what you are putting in.

Now obviously this is only the case when you have a headwind. If the wind is off enough to the side, then the wind would only be pushing you to the side. You must remember though that the blades will get the relative velocity of the wind (i.e. must add on the velocity of the boat).

It just seems like if this were to work, then it would be a perpetual motion machine. The boat gets going, and the propeller moves it making it faster, thus making the wind velocity faster moving the propeller faster making the the boat faster, etc, etc.

 

[Huckleberry]

I don't think sailing into the wind would work either minger. I don't even think windmills would be as efficient as sails in any case. The only things I've seen them on are a few photos of small catamarans.

 

[Danger]

I feel your pain, man. It took me over 20 years to design a fighter plane that could do 8 Mach for my book, and by then everything else was obsolete.
I'm not going to refer to any specific quotes here, because this thread is way too long for that. Basically, a windmill would essentially be a very low-efficiency sail, and therefore counter-productive as Huck pointed out. If you really want to use the propellor set-up, rather than oars, I would suggest that you look into providing a bunch of pedal set-ups all geared or chain-driven together. Paddle wheels are not really all that lacking in efficiency, though, and side-wheelers give the advantage of differential steering.
It seems to me, with my poor memory stretching as far back as possible, that the 'wind turbines' referred to on a ship were in fact experimental self-adjusting sails rather than being hooked up to some mechanical system of torque transfer. The theoretical advantage was about allowing a sharper tack angle than a conventional sail does.
A couple of things that I should mention as a reader and writer of the genre: Don't use the term 'sci-fi'. It's considered a serious insult, taken by an SF fan to be equivalent to calling his wife a whore. 'Godzilla vs the Smog Monster' or 'The Butterfly Effect' was 'sci-fi'. And real SF, as opposed to fantasy, does rely upon the scientific aspects being at least theoretically possible, so you're definitely working in the right direction by seeking tech advice. Remember though, that it is above all about the people. Technical mistakes are forgiven as long as you have a good story going.

 

[Ivan Seeking]

Flettner Rotor

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

Here are some Google hits

http://216.239.37.104/translate_c?h...rotor&hl=en&lr=&rls=RNWE,RNWE:2004-21,RNWE:en

http://naca.larc.nasa.gov/reports/1925/naca-tn-228/index.cgi?thumbnail1

http://www.tecsoc.org/pubs/history/2002/may9.htm

 

[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.