Windmill or Wind Turbine- powered boats: how many are out there, and are they viable?

You misunderstand me. By "direct" I mean connected to the propeller directly with shafts chains gears or whatever in the same way as the pedals of a bicycle are connected to the wheel or the engine of a car is connected to the wheels. I did not think electric transmission would qualify as "direct"

 

Windmaster
Just to be certain I have this right as far as what is excluded and what isn't on a turbine to qualify for this thread.

Are freewheeling hubs allowed as on most bicycles or must they be locked gears. Is any gearing allowed. Or ratios fixed 1:1.

Are clutches allowed as in manual cars. I guess torque converters as used in automatic cars would definitely be disqualified.

Assuming gears qualify; must gear ratios be fixed or can they be multi-ratio - I guess they would have to stop to change gear as cluches are not permitted. I suppose CVTs would definitely not be allowed as these are getting very close to the flexibility of electric systems.

Using varaible displacement hydraulics would be far too indirect to be allowed. These are getting way too close to the flexibility offered by electrical systems.

Using variable pitch props/turbines would be like changing gears so it could never be classed as "direct" either. So these must be excluded.

So the only thing that qualifies under your definition is where fixed blades are mounted on a common shaft. This then qualifies:
http://main.org/polycosmos/silicbar/sailscrw.htm
Everything else needs to be excluded as it is not "direct".

I am aiming a little higher on the technology scale.

If you go through the analysis for all points of sailing you can determine that the best results come from having variable gear ratio. Into the wind you need the effective pitch of the air turbine to be about twice the water prop. The ratio can get closer in stronger wind - maybe 1.6:1 if the system efficiency is high. Downwind you want the speed ratio to be 2 water to 1 air and beam wind is somewhere in between like 1:1 - again depending on wind strength. With my system I do not need to worry too much about all this as the wind turbine will continuosly hunt out the maximum energy recovery and the boat will be set at a fixed speed. Any energy excess or shortfall will be averaged by the batteries.

I have chosen electric transmission because it gives very wide range of speed ratios very simply, can be easily automated (trimmed), results in a lightweight system, has little constraint on positioning devices, has fair overall system efficiency, is cost effective, is clean, is easily adapted to efficient energy storage, can store energy at rest and can be automated easily to continuously maximise energy recovery while the boat holds a constant speed.

I have not constrained my thinking to a single form of power transmission. I have made a selection on the most suitable for the application. If you limit horizons to only fixed mechanical transmission then you limit the possibilities tremendously. My goal is practical use of the idea; not some narrowly defined demonstration that the idea works - of course it works. It is just that it is obvious when you use electric transmission but much harder for most to comprehend using mechanical transmission.

Rick W.

 

Apologies, I guess every kind of drive is "direct" then.
I would like to discuss the differences between the electrical drive system and .......... (what term should be used for a drive that is not electrical?) Can you help here? - how about "mechanical drive" would that be ok?

 

I'm not an electrical engineer, can you clarify.
Electrical transmission means this: the wind-turbine drives a generator, power is fed through wires to an electric motor, that drives the water propeller?
This will provide power to drive your boat directly upwind with no additional power.

Or, the above, plus extra power from your batteries that you have gained from the wind-turbine whilst moored, and solar power obtained all the time (in daylight that is).

Which are you aiming at? The first one where you don't use stored energy? or the second, where you use stored energy. Or maybe it will work in both cases?

Sorry to be a little slow, but I just want to visualize how your system will work.

 

The way I see it, a wind turbine serves well as an electrical generator, which is it's most common use. It seems crazy to me for anyone to consider using one without the ability to store a charge aswell.
I don't want to sound like Rick's groupie or anything...but I think the combination of solar panels, batteries, electric motor and wind turbine, is a very tidy system. The solar panels are space efficient. So is the wind turbine. The batteries double as ballast. The electric motor is far more reliable than a piston engine. The power supply is regulated and not wasted, as wind is by no means reliable. As I say...a very tidy system.

As for wind turbines being used on large freight ships or passenger ships....I think that it would need to be a scaled up version of Rick's design. Reliability is the magic word. However, I wonder if this would ever happen. When the oil supplies run out, nuclear power will become very attractive for large ships.

I hate the idea of having an ocean full of nuclear powered ships. They become targets, and have the potential to spread radiation. USA submarines and warships carry nuclear power plants which are supposed to melt down into a self contained blob with no radiation leaks. Yeah right.

Hydrogen power is not realistic unless we have an efficient way of extracting the stuff. Refined vegetable juice is not an option.

Because large ships are so inherently efficient due to their size, perhaps a battery powered ship that recharges at each port is an option???

I still like the idea of a solar/wind turbine ship best of all. We would need to convince the economists that it's better than nuclear.

Hang on....we still have heaps of coal. That's cheap, and green if you compensate by planting trees to help the atmosphere. Hmmmm.....I think wind turbine ships could be something for the very distant future.

 

In strong wind I can recover excess energy from the turbine and store it when on any point of travel relative to the wind.

The amount of energy stored or expended will depend somewhat on the selected boat speed as both drives have the same peak power limit. For example the turbine will generate 1.4kW in 12m/s wind while the boat only requires 0.5kW to do 5kts. At design speed of 7.5kts the water prop requires 1.45kW providing the wind turbine is not contributing to drag, so apparent wind is beam on say. The physical limit for both units is 9.6kW so there is a large reserve relative to the design condition.

At full power to the water prop, the boat will do 11+ knots. I have not looked at what speed is possible with full power on both water and air props. If I could achieve this condition the battery charge would only last about 30 minutes as total demand would be 19.2kW. The drives are speed limited as well and peak speed for the water prop is just above the the peak power point so it is unlikely that I could ever get to full power from both drives at the same time.

In summary I am not constrained to an energy balance in any point of time. With suitably strong wind I could be storing energy while making good speed on any point of travel relative to the wind.

You could do what I propose with a mechanical power transmission but you would need a decent flywheel with wide ratio CVTs connected to both wind and air blades. Not as nicely packaged as battery electric.

Rick W.

 

Rick
I imagine a flywheel would need to have a magnetic bearing and spin in a vacuum, or it would need to be a very large, heavy flywheel. Doesn't sound practical for a small boat (as I'm sure you would agree), but maybe it could work on a big ship. I guess it depends on how long the flywheel will need to hold it's spin. CVT?? I assume you mean mechanical continuously variable transmission? Do you know much about that? Has that technology become viable?

Back to your boat now....In a worst case scenario, you will be sailing in windless, overcast or rainy days, and windless nights. What sort of distance would you expect to travel, if the batteries are not being charged? (assuming they are fully charged at the time when you are becalmed). Sorry if you have already mentioned this.

 

Correct with CVT. There are some reasonably nice units made for vehicles but I have never looked for units sold separately. I am very comfortable with electrical systems so no need to look.

The range is very much a function of speed. The wave resistance does not kick in until over 10 knots so below this speed the power consumption is related to velocity ^ 3. In calm conditions it will take 500W to do 5knots. This will give usable range on battery alone of 100nm.

Even in overcast conditions the solar cells will collect power.

My goal will be to hold around 7 knots for point-to-point coastal cruising overnight where I am able to start with a full charge and end a run of a day or so with little charge. This will be the fun part working out what speed to run at. In the tropics I would expect to be able to do at least 7.5kts most of the time using both wind and solar energy collection. The six solar cells have rated output of 220W each so in the midday sun I can hold around 7knots on solar alone.

Rick W.

 

sounds good

 

Rick.
I see where you are coming from. I also took a look at your website. Your figures add up.
I must comment on something: You say the turbine will generate 1.4kW in a 12m/s wind - that's about 2hp right?
Do you think the actual (mechanical) power (bhp) of the turbine is the same or do you think there is a loss in the conversion to electrical power? If so how much?

 

The figure is based on force limit of 250N and electrical efficiency of 85%. I have not yet settled on the generator. The best I have looked at get an overall conversion efficiency, including controller, of 90%.

Rick W.

 

Rick, I've been looking through your website. Your original concept drawing looks seriously cool. It looks like one of those fast prehistoric sea creatures. Really, it has nice shapes and it's very interesting to look at. A real work of art.
And then you had to go and make it all super-practical and efficient...and seriously compromised it's looks!!!
Feel free to tell me to piss off! regarding this matter. I understand that functionality is more important...but can't you have the functionality and look good too? I'm not suggesting the latest design looks bad. I just think the original one looks fantastic. The magazines would love you for it.

 

Richard
The first one was capable of 12kts with the same full power and 8kts with 1.5kW. The raked windscreen looks better than vertical but I intend to mostly operate from inside so I need good visibility. Raked windscreend are not good once they get a bit of water and salt caked on them.

The other problem was the stability and tight accommodation. I had trouble fitting in two bunks with a passage way.

The stability is quite impressive now for such a narrow hull. The batteries weigh 260kg and their CoG is below the bottom of the hull. The detail hull design is not yet complete so it may still go through further evolution of the shape.

Rick W.

 

Fair enough, Rick (regarding the styling).

I can't see the point of making anything demountable, other than the wind turbine. If it's on a good submersable trailer, why would you want to pull the whole thing apart? Getting it in and out of the water could still be a one man job, using an electric winch? Or am I overlooking something?

 

Design of the Solar Wind Boat

Rick

Having looked at your design, I have the following comments to make:
Positioning of the wind turbine:
You are mounting it on the extreme stern of the boat I think this may lead to handling problems. In a beam wind. Using two blades - which is what you intend - you are running the turbine a high-speed (8x windspeed?). The disc of a high-speed turbine presents an almost total obstruction to the wind (remember Lin Olen's comment that a fast-rotating windmill pulls better than a spinnaker downwind) - If you don't believe this you only have to think how an autogiro (gyrocopter) works.
So what it really amounts to is the equivalent of a sail the size of the swept area of your turbine mounted at the extreme end of the boat. With this running so far aft of the CLR in a beam wind you are going to get a considerable yawing force away from the wind at the stern, and you will have to use considerable rudder authority to counteract it and I notice the rudder shown on your drawing is absolutely tiny! You could get round this of course, by mounting another turbine at the bows. Or mounting the turbine on or near the CLR.
Going directly into the wind however the drag from your rear-mounted turbine will serve to keep the boat going head to wind - however you could have a problem when you want to turn away from the wind!
Maneouvrability: You seem to have designed the boat purely for high speed without any regard for handling - the turning circle would be very large indeed and there is a total lack of "rocker" on the hull which is the feature that allows a boat to "come about" more readily. You could certainly be embarrased when you attempt to turn in a harbour or narrow river.

I think the purpose of these forums is to share ideas and constructive criticism and not to just complement each other.

It would be nice to hear the comments from any others who are interested. Whether they agree or disagree about my understanding of Rick's design which he has shown to us and therefore invites us to comment.