another idea

LL
Post 47 above has a good example. It roughly agrees with what I have determined although both the turbine and prop are larger diameter than I believe is required but then it looks a heavy boat.

I made a model boat many years ago that would make slow progress to windward but discarded the idea as ineffective. However that was before I knew how to design efficient blades.

Overall I believe the combination of solar and wind via batteries in an electrical system provides the best solution for a cruising boat. With decent batteries you can store energy to make real speed when required or average out the energy collection to set good steady speed. Placing the batteries low means you can build an easily driven narrow hull and still have ample stability.

Fitting a turbine to a deep keel boat would not make a lot of sense. Fitting a turbine to a catamaran would be better. You can do away with keels/dagger boards and big rudders as leeway can be compensated for by just sailing more directly into the wind.

The electrical system gives great flexibility. Of course all the components need to have good efficiency as each link in the power transfer chain robs a little power.

You can design turbine blades that do not require much force to generate useful power. I have designed a 2.2m diameter turbine that will produce around 1500W with 150N of drag in 12m/s (say 25kts) wind. So the best blade design is somewhat different to a normal land-based wind turbine where you are not too concerned about the force to hold it against the wind.

Rick W.

 

I remember a concept from the 50's that involved vertical windmills a la Calypso II. The idea has been around a long time and does not violate any natural laws.

Given that it will/should work, the question then becomes, why bother? It looks complicated, expensive, risky and unseaworthy. The only advantage I can see is the ability to negotiate narrow waters without tacking. I doubt if it is as efficient as a sailboat and imagine having to take in a reef ...

On the other hand (as the guy in Fiddler on the Roof was fond of saying) it looks like a lot of fun and allows one confound the sceptics, something that always gets my vote.

 

I am sure it is possible to go against the wind with such a device as shown.
When the wind is incident on the rotor vanes, it does exert a pressure on the hull, and the rotor, depending on the frontal area.
However, its the kinetic energy of the wind that make the blades go round and that rotary motion can be translated into a propeller rotation. The energy that is delivered to the propeller after the losses, should still be enough to overcome the air pressure, if the wind speed is high and the wind mill is efficient enough.
A Savonius type wind mill could trap wind from any direction, including dead ahead.

I think I will make a model and try it out

 

The designer is ¨Windmaster¨. He is a member of ¨Boatdesign.net¨ and a frequent contributer. He is very knowelgable about WT boats and if you need info look him up here. I have always found him very helpful.
And yes, these boats DO go up-wind very well. They preform great too.
Richard Miller; Chile, SA

 

Introduction and initial comment

Hello everybody,

Since this is my first post to this forum, I would like to offer my credentials for posting comments here. I am 61 years old and have been sailing around 8 years in conventional sailboats that must tack to make headway to the wind, and as an engineer I have often wondered, as I was sailing, why some way of heading directly windward wouldn't be a lot better since the force of the wind is maximum at that point. Recently, during a discussion with other sailing comrades the subject of direct windward sailing came up, and of the 5 participants all of them without exception made the usual claim that such a feat was impossible, some in an insulting fashion that irked to the point of creating a strong desire to prove them wrong. I rushed to the machine shop and furiously cobbled a small vehicle together from hobby components that laid waste to their ignorant claims, and settled a gentlemens bet to everyone's satisfaction. This took the form of a small wheeled car that had a wind turbine driving a belt to the wheels. A small rudder vane keeps it automaticaly pointed directly windward. It zips along quite briskly into the wind, and actually accelerates once moving because it generates a large relative wind as a result of it's new forward motion. There is no reason why this would not work with a boat hull as the vehicle. The argument most often heard is that the drag on the turbine would kill the whole idea, but that is nonsense, because in this situation the drag is tiny fraction of the thrust (torque) developed. Another point worth mentioning is that that the force of the wind increases as the cube of the wind velocity, so going faster only makes it even more effective.

One more comment I would like to inject, and that is that an airfoil is a mechanical amplifier, converting a small pulling force (against drag) into a relatively large lifting force. Few people realize that this lift is actually energy liberated from the atmosphere in much the same way as energy is extracted from expanding steam, the only difference being that the venturi effect does the expanding, and the atmosphere is the 'steam', which technically speaking is the superheated gas of liquid air. Sails, wings, propellers and windmills all extract caloric heat from the atmosphere and leave a 'cold wake' behind. This energy is what creates the lift, not the drag forces or engine thrust.

If anyone is interested, I would be glad to attach designs and further info as to my current efforts in this direction.

 

MP
Welcome aboard.

I am interested in basic data from your vehicle. Some pictures would be useful to enable an estimate of drag. The type of prop, gearing, wheel diameter and performance such as speed in different wind conditions.

I am after data to verify my engineering model of the system.

If you are interested in refining the design and putting it on a boat I can help you with hull and turbine/prop design.

I just have too many things to do to test all these things out to optimise their performance.

Rick

 

Question about designs

I am new to this forum, so if this has been discussed, I am sorry to put you through it again.
I am building a light weight 18ft electric boat, and am in love with a stern shape that is called a "ducktail".
I would imagine that because it is such a bear to build, there must be a purpose to it other than its looks alone.
As a woodworker, I almost have to build it just to prove to myself I can.
Does anyone know its original purpose, or is it just for looks.
It is clear of the water, but adds length, and weight. does it do anything usefull so that I can justify building it on, or is it just added ballast?
I don't know which catagory this question would fall under, but the people on this page seem to know their stuff.
Can any one help? Thanks in advance.

 

You need to consider the boat in operation to appreciate the merits. As the speed increase the hull will squat and the transverse wave will create a trough that the ducktail squats into. This increases the waterline length. There wake is left less disturbed than if there was a transom leaving a low pressure trench behind the hull that adds extra drag.

So it does make sense for a displacement hull. Less energy is lost to wave making and turbulence.

A canoe type stern where the sides come together at an acute angle similar to the bow will also leave a clean wake.

Rick W

 

My next step...

Rick,

Thanks for the quick response. My next step may seem not related, but I am building a bicycle sized version of my first stab at this. My first model was not sophisticated enough to gather useful data, but was more to recover my good name as an engineer, and to make sure that my friends did not think I was crackers. One thing I figured out is that it is not really the actual wind that matters, but the relative wind the rotor perceives. In principle if it is possible to feed some of the wind energy back into forward motion, the turbine would have a hard time separating that new wind that was caused by the forward motion from any existing wind. I reasoned that what the bicycle version might be able to do is to use muscle power to bring the vehicle up to 'flying speed' of the turbine, after which a small residual rider imput might be sufficient to keep it rolling along. I realize this starts to sound like free energy, but that is not true, because there is a fantastic amount of caloric energy trapped in the atmosphere at all times, it just takes some form of machine to extract it. We plan to run some tests of this idea soon out here in the California desert at El Mirage dry lake, which has an almost constant wind condition. We are using bicycle components because they are extremely well developed and very reliable and available. In a nutshell what are building is a bicycle trailer with 5 ft diameter 8 bladed wind propeller driving the wheels via a standard bicycle chain and sprocket.

 

That looks good. Clever simple test set up.

One of the problems with small scale, low speed turbines is their poor performance at low Re#. The bigger you go the better it gets. So scaling up as you have done will improve things anyhow.

I made a 2.2m diameter 2-blade horizontal turbine mounted on a right hand gearbox with a vertical shaft. I waited for a nice windy day to test and I could not stop it once it got going. The tip speed was around 8 times wind speed. I had to jam the blades into bushes to stop it before it took my head off. The gyroscopic force was amazing. The blades were only fibreglass over balsa with an aluminium former but they developed a huge amount of energy. Damaged the tips when I stopped it.

I am not sure there is merit in going to more than 3 blades. The aim is to get the most efficient turbine not to maximise the energy recovery from the stream. I am only using 2-bladed turbine. I aim to work with low velocity ratios over the prop so I get high efficiency. This application is quite different to a static turbine where the aim is to get as much power out of the air stream as possible. You need to extract the power at high efficiency so the drag or thrust force on the turbine is low.

I used an MA409 foil section for my blades as I have found them to be a very effective foil for low Re# applications. What you have drawn look like standard wind turbine blades and I do not believe these provide the most efficient result. If you have a section profile I can have a look. A slightly simpler foil to make is an E193.
http://www.ae.uiuc.edu/m-selig/ads/afplots/ma409sm.gif
http://www.ae.uiuc.edu/m-selig/ads/afplots/e193.gif

I am certainly interested in your testing and results.

Rick

 

My reasoning for the 8 bladed prop....

Rick,

...is so that I can remove blades from my design and reduce it to a 4 or two bladed version for comparison. Adding blades to a 2 bladed prop would be harder. Also, I have tried to focus on developing torque rather than rotor speed, so that more of the effort is directed radially and not axially. I know what you mean about the power these things develop once they get going, running without a load is as dangerous as hell. If I told you what I am using for blades you would probably laugh, and because they are shaped more like curved scoops rather than foils. I made them from sections cut from large diameter new Schedule 40 ABS pipe that I cut along a spiral path on the tube. This material is made with a skin and a foam core, and is flexible and virtually indestructable. It is thick enough to dress a very nice leading and trailing edge profile on it. And it is dirt cheap, so easy to modify and make more blades. By cutting along a spiral I can vary the amount of lead change further out on the blade. At the base I have a relatively large area exposed to the flow so it has some considerable startup torque. I'll try and get you a picture of the propeller soon.

 

Rick,
Thanks for the fast response.
My boat will indeed be a displacement type hull, and very slow speed at that.
Should the ducktail be located at a certain height in relation to the waterline, and should it be flat in profile, or slightly "V" shaped like the hull.
Considering that the ducktail will be a semi circle the width of the transom, It will add about 24" of length when submerged.
I will also be putting the propellers near the end of the transom step, so they will be about 24" also from the end of the ducktail.
Will this have any adverse affect?
I am using 2) 50# trolling motors slightly modified as the power for the boat.
They will also do the steering.
The boat is 18 ft LWL, with a 60" max beam, slight vee bottom for stability, and the ducktail will add about 2 ft more if it hits the water.
I am using using a rounded chine, and want that old boat look.
Is the ducktail worth all the work?
It sure does look cool.
Thanks in advance. Tom

 

Maybe, but the boat in the picture is not sailing to windward -- it is motoring to windward using a water prop for forward propulsion instead of the wind.

It is not sailing, it is motoring by using the wind INDIRECTLY via the water prop for propulsion.

Maybe, but motoring into the wind does not and that's all that's going on here.

Right, it may not work if the drive were in the air but it is not.

There seems to be a couple of guys here who like to argue and theorize and confuse the issue rather than paying attention to the simple facts. What's so hard to understand about extracting 10 HP from the wind and using it to spin a water prop that moves the boat into the wind?

Sounds like a good application for a continuously variable transmission.

 

Tom
Have you got a picture or drawing of what you have in mind.

To my mind there is not much point having something unless it affords benefit. Agreed that could be just to get a certain look.

I would need to see more detail on what you have in mind and hope to achieve overall with the boat. Even a simple sketch would improve my understanding.

The overhanging stern really only comes into play when reaching hull speed. It does not sound like you will have the power to get there in the first place.

Unless you have a good idea of what you are building it will pay to buy proven plans of something that looks like what you want. There are thousands of plans for small boats and a lot of people here who can guide you in selection.

Start a new thread regarding your boat and see what comes of it.

There are no dumb ideas or silly questions.

Rick

 

Ken
Your use of the term motoring is misplaced. A motor motors not a turbine. The term sailing might be misplaced but motoring makes less sense.

Maybe wind powered water propelled boat.

I agree with a CVT. It would be really nice. Variable pitch on the turbine or prop are alternatives but the CVT is probably the best way. It is just like tuning sails then. You can keep pushing speed until the turbine begins to stall. With fixed speed transmission you have to set the gearing so it will make way in light air and this is not optimal once you get moving. The efficiency of the turbine really picks up once it develops speed.

Rick