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

Yes, that's also true but I didn't mention it. Thought I said enough already!

 

That might seem obvious but the difference is not that great. My turbine is 2.2m in diameter. Compare the swept area with a laser sail area. Not much difference.

In practice the laser would ghost along when I was stopped. The mechanical friction in my system is not high but compared to none it is huge. So a sail has an advantage here.

The other factor is the Re# of a sail with a chord over 1200mm for much of the height versus 120mm on my blades. Even with a tip speed of 10 times wind speed only the tip has similar Re#. The rest of the blade is lower and less effective until the wind speed is sufficient to get the Re# up to where the L/D for the blades is less dependent on Re#.

The depth of the sail can also be adjusted whereas my blades have fixed thickness. This means the sail can be tuned to the wind strength.

I was just getting in steady convincing motion around 4kph when the laser was being pressed hard. In conditions where both boats were pressed, say above 30kph, I might be competitive going to windward and maybe even reaching. I would need gearing to go faster downwind.

Rick W

 

I can very easily feather my turbine or adjust the amount of power using the spider. I can stop it spinning and go in reverse if I want to.

On the safety aspects the spider sets a distance of approach. You have to reach in over the spider to get to the blades. Also my turbine weighs 1.5kg. It is made from foam and fibreglass with a carbon fibre skin. It does not have much kinetic energy.

I can feather the turbine at any time by turning it off the wind. Variable pitch results in a compromise on the blade pitch. It would need to be weighed up against a CVT for a mechanical system. The simplest is to use fixed pitch with electrical transmission and battery storage.

If you do not run with high tip speed then the Re# is very lower and L/D very poor compared with conventional sail.

Any out of ballance force caused by blade weight is minute compared with the out of ballance caused by varying strength wind across the blades. I have not bothered balancing my props or turbine blades.

You will be hard pressed to validate your assertion that low speed blades are better than high speed re point 6. It is nonsense.

I have some speed data and video of what I have done so for now the challenge is 5kph. I know I could go better in higher wind without risk of anything breaking. Maybe up to 7kph directly into the wind and possibly 10kph on a reach without risk of capsizing. With CVT and slightly larger prop I might give a sailing dinghy a go in a good breeze. However with an electric system and battery storage I would kill most sailing dinghies.

One advantage that the boat certainly has is that it can be carried by one person. Heavier than a sail-board but easier to manage than any dinghy.

So the challenge is there - who can do better than 5kph?

Attached clip is at a distance and the camera does not follow the boat so it is easy to assess speed. It takes 7 to 8 seconds to make a boat length of 7.2m so close to 1m/s or 3.6kph directly into the wind. This was very relaxed on the drive system so it is capable of much higher power transfer and somewhat better speed.

Rick W

 

well, wikipedia (http://en.wikipedia.org/wiki/Laser_(dinghy)) says the standard main is 7.06m2, almost twice your 3.8m2. I see your other points though.

And power/area isn't the main issue with the practical issues of turbines (unless one picks an arbitrary limit). Total power/drag and related power/moment define performance potential. Not to mention the fear factor...

It is cool to watch though. Thanks for doing the work and posting videos

 

The sail area is in the ball park with the swept area. It is the Re# that is the performance killer until the turbine gets up a few revs. Both lasers had an adult and kid plus a lot more boat and drag than I had. With a 2 to 3sq.m wing sail I expect my V11 boat would eat them. I can easily beat them around a course when I am pedalling.

It is a fascinating system and with proper design and manufacture you could arrive at something that would challenge a dinghy. It is a great sensation to turn up into the wind and power on.

I know for a fact my 2.2m long turbine blades are much easier to handle than the mast of a laser.

The little turbine could inflict a bruise or cut but so can the boom of any sailing boat. I also notice smart windsurfers use crash helmets. A friend at the lake now wears one after he found himself gulping water from being knocked out momentarily with the mast when he went over. He could have easily drowned.

My control spider works well as an approach guard. It is not as effective as a cowling but that would sap performance.

My turbine blades were very easy to make - about 6 hours work in total plus epoxy curing time. The most expensive bits are the two gearboxes. I would like to work out something with less friction but then why not use electric and battery and make something that works really well.

Rick W

 

Rick
I'll ignore the insulting aspect of your final comment.
I do know this, since I have done practical tests. It think your assertion is based on theory alone without actually trying it out.
You can easily check it out using models, without going to the expense and difficulty of building fullsize. You should be more open-minded about this!

 

If it is more than nonsense then show me the test data.

I have demonstrated 5kph in quite mild conditions. That is hard data.

You seem to think all those Aeolus people apart from the trike are on the wrong track. Funny how the trike achieved maybe 1kph and the others were around 18kph. That it solid evidence of what works best. Plus you must believe all the wind turbine designers are on the wrong track.

An argument without facts is nonsense. So far you have not offered any factual evidence.

Rick W

 

I'm not saying anyone is on the wrong track. The Aeolus machines work ok, so does yours. You proved it. I'm just saying there is more than one track, and the track I'm on makes for a better all-round machine. Yours doesn't work any better than mine in 1995. To say it's "nonsense" when you have seen videos of it working is really silly. Have you seen my model videos? I don't know why you're trying to make a ridiculous competition out of this. You must know that 14 years ago we didn't have the technology available for gps traces etc. that's unfortunate, be fair.
I'm sure you also know that the "wind turbine designers" are designing for a different thing than we are (fixed base) so really your comment there is not relevent.

 

The purpose of the majority of small boats is to travel. That requires to cover a certain distance in a certain time. Many boating activities are based on this simple objective. It is no good saying you can move if you do not know how fast you actually move. You had the tools in 1995 to measure the speed of the boat simply by letting it passage past some object. As I said my best estimate of your speed is 2kph. I have already more than doubled that and yet you still believe a large pitch multi-bladed turbine is better than I have.

You need data to prove a point.

The land based turbine designers are concerned with the forces as they have to be managed. It gets down to the cost of the structures to handle the loads.

Anyhow you have your video with no attempt to measure the speed and I have both video and GPS data. Any observer can see which turbine is more effective at traveling over the water.

You said your models prove the point you make. Lets see the side-by-side comparison if that is so easy to demonstrate.

This reminds me of the nonsense Hobie use to sell their flapper drives. Have you seen the tug-of-war video:
http://www.youtube.com/watch?v=CKlvY5vDrL0
Makes the gullible want to rush out and get one. They are lead into believing that they can get out on the water and beat olympic kayakers with their brilliant flapper boats. They get sadly disappointed when they compare their speed over the water with anything other than a 6ft long sit-on.

The lesson here is that bollard pull has nothing whatsoever with actually travelling over the water. The only relevance is for towing. I doubt that many human powered craft will be called on to tow and likewise for wind turbine powered boats.

I think you are deluding yourself about what performance is. It is not only a matter of getting from A to B but time to do it is also a key factor. I could make a tubi-prop boat with my existing turbine that could drag you off your feet. It is a matter of gearing. But thrust is not the objective. Travelling over the water is the objective.

Rick W

 

I have a very simple demonstration model. Single shaft, 14 inch diameter windrotor. This is for sailing direct into the wind. It's the one in the video I recently uploaded to youtube. http://www.youtube.com/watch?v=iygLgI25WOg

If you could make one of yours with the same rotor diameter. That would be interesting.
I'm not sure if it would be easy to compare them, but it would be a start.

As a matter of fact, I'm intending to put plans on the Internet for this model or "toy". Very soon.
....

 

From what I can see in that video the boat is not actually moving. It is pulling on a piece of string or wool. The purpose of most boats is to actually move. You need to measure the time taken to travel some distance. The force is simply the urge to move. If it is not actually moving then it is useless for the intended purpose.

You need to start thinking about MOVING - actually travelling somewhere. A wind turbine boat is never going to be used as a tugboat so the pull is meaningless. It has to be able to move with some speed. That means distance in a given time or time to travel a given distance. It involves time AND distance - not force.

You need to set the model free and see what terminal speed it can reach. The best would be to buy a 14" model airplane propeller, mount it in reverse on an identical boat and run them side-by-side. I know which one will go fastest if they are both set up most advantageously. It might give you a better understanding of force, speed, power and efficiency. You will soon see why I seem anal about the system efficiency.

By the way I did analysis of the Hobie flapper efficiency and at normal cruise speed the flappers on a Hobie Adventure get 36% efficiency. At full effort for the average person the efficiency lifts to 50%. I can get 85 to 88% for a propeller on my boats for the same power level. However I would be pressed to outpull the Hobie. If that was my objective I would make a very low pitch prop about 1200mm in diameter and then I could take on two or three Hobies. But my objective is to move across the water not participate in tug-of-wars on pedal boats.

My current folding prop on the pedal boat has blades with a 25mm chord and 3mm maximum thickness. If I applied full power at zero speed I would bend the blades:
http://www.boatdesign.net/forums/at...51015850-pedal-powered-boats-folding_prop.jpg
But my objective is not sprinting. It is to cover long distances in the shortest time I can with an early model engine.

Rick W

 

So are you saying that when they measure the thrust of a jet engine, it has no relation to the speed of the plane?

 

There is absolutely no correlation between the thrust and speed. It is absurd to think there is. This is the way they con the gullible into buying the various electric outboards. The static thrust gives a number that looks signicant. 54lb looks a lot better than 0.3kW. It is the power that counts not the thrust.

On jets I have attached details on two examples to show what I mean. One has combined thrust of 1380kN and does 430kts. The other has thrust of 289kN and does 1740kts. The ratio of power to speed in one case is 3.2kN/kt compared with 0.166kN/kt. The thrust has no correlation to the speed at all.

Measuring force is pointless if your objective is to move. You need to measure speed.

Rick W

 

"There is absolutely no correlation between the thrust and speed." - you said it!
So therefore, if a jet is flying slowly, and the pilot opens the throttles to increase the engine thrust, you are saying it makes no difference to the speed.
Well they certainly needn't bother with reheat then!
Similarly, opening up a speedboat and increasing the propthrust does not make it go faster.
Quite surprising, I never knew that!
...

 

Let me help you, what you really mean to say is that thrust and speed don't necessarily correlate because there is another factor involved - load.

A high thrust may not move a heavy load as fast as a low thrust with a light load.

Simple isn't it!