Wind turbine powered boat Design

We are a company who is designing a new type of wind turbine. In order to generate PR and marketing activity, we want to make a boat that is only powered by wind turbines and is running on electric motors. In the first phase we want to cruise in Europe and maybe later on try for more ambitious destinations. This is in many ways similar to first solar powered yacht project that went around the world in 2012.

We are a small company and with limited financial resources so we try to get as much information before going ahead with this and I will be thankful if you could give us any kind of possible help and advice. I have done some sailing when I was younger but other than that have very limited knowledge of boats.

1) If we are thinking of a crew of 4-5 persons and running on electric motors, what is the best boat design for such configuration? The solar yacht used a catamaran design, what do you think? What length do you recommend because of the length of cruise time?

2) Where can we find such a design or can you recommend a designer and what is the approximate cost?

3) What is a good material to use considering the weight, strength and cost?

4) Where can we find the crew for such project?

As i mentioned, I am an amateur so anything else that I have forgotten about and you can help us with is highly appreciated. Thank you.

 

Windpower, welcome to the forum.

Yours sounds like a complex project, and so you will likely need some significant professional help to design and build a proper craft.

First, I would imagine that the general understanding of wind power is rather like solar power in that it is a low-energy source. Boat performance relies heavily on power-to-weight ratio, and since the power is low, so the weight should be low. This also speaks to having a hull that is very low drag. Therefore, like the Solar boat project from Switzerland, your boat would most likely be a catamaran for light weight and low drag. If the vessel is, say, under 60'-65' long (18 to 20 M), then carbon fiber composite would likely make the most sense-very light and strong. Going larger, carbon composites can get pretty expensive for the shear amount of material that you would need, and so for really large craft, I think aluminum could be a suiable alternative. Of course, if you are really successful at fund-raising and sponsorship, raising a lot of money for development, there may be sufficient funds available to really build an optimum vessel.

It will be difficult to suggest a size of boat at this stage because we don't know the power output of your wind turbines. Therefore, you should look at first doing a feasiblity study with a naval architect who can help you determine the most appropriate size vessel for the right cost. You may want to do a smaller prototype first, perhaps buying an older used boat that can be adapted with your gear to prove your concept. Then with the testing and success of the prototype, you can move up to a more sophisticated custom vessel.

Since this is a rather undefined project as you have posted it, it is going to take some thought and some inquiries to come up with design cost. The cost for the design will depend on the scope of the project and the size and complexity of the boat. And some of those questions aren't answered yet. You'll have to ask around to some naval architects to see what they can offer you. But to do that, you should create a business plan and a Statement of Owner's Requirements (often refered to on this forum as an SOR) which specifies precisely what you want this project to do, what it should look like, and how long you think it will take. Suggest a budget if you can--how much money do you want to spend? How much sponsorship can you raise? The more you can define your requirements, the easier it will be for a naval architect to respond with a reasonable reply.

As for crew, there are plenty of crew placement organizations and businesses that can help you find crew. In the megayacht world, you can look to the centers where large yachts gather, such as Ft. Lauderdale, FL, or Newport, RI, for crew agencies. In Europe, I would imagine you would find the same along the Mediterranean coast (Barcelona, Majorca, Monte Carlo, Athens, etc.). In northern Europe, look to the west coast of France or Paris or London.

I hope that helps.

Eric

 

For maximum speed vs. power input, there is tons of great stuff in the http://www.boatdesign.net/forums/boat-design/pedal-powered-boats-23345-38.html#post621519 thread. I really liked Coach Dave's 28 ft long boat with a very simple skinny main hull and twin small stabilizers. You can see that one guy pedaling away can push this boat with tons of gear on board boat at an amazing speed at http://www.youtube.com/watch?v=oxwTNn_7OKk.

Somewhat successful wind turbine powered boats have been made (mechanical drive). Back in 2010, we had a poster (Thomas T. Bradshaw posting as High Tacker) with first hand experience. He described his boat, Catbird Suite, in http://www.boatdesign.net/forums/boat-design/sailing-directly-windward-27000-2.html

He also has his own web site http://www.damsl.com/ that has a page with more details.

Also in the same http://www.boatdesign.net/forums/boat-design/sailing-directly-windward-27000-2.html thread, there was some good technical discussion (especially by Ingmar Hendriks posting as SpiritAmsterdam) about the advantages of using turbine powered high efficiency generators to power high efficiency motors in their wind turbine powered land vehicle effort. With the right electronic controls, this arrangement allows operating the wind turbine and motors at optimum speeds that are independent of each other.

 

As to the around the world solar boat...

The above boat was funded by many and promoted solar power in general, so even competing companies worked together on it. Your project will be funded only by you to promote your product over others. Of course cost depends on how big the boat has to be and that depends on the conditions it will encounter but also on how big and the configuration of any wind turbine electrical generator that will go on it, how many batteries, etc. Nothing is offered as to that, so it's hardly possible to estimate a cost when nothing is known about what is needed.

Is this a wind turbine for powering boats or one for powering cities? If for land use, I wonder if money might be better spent elsewhere than plowed into what is more or less a promotional 'stunt'.

 

An interesting project! You'll have to be careful though with power losses. Converting wind power to electricity to make a boat move maybe less efficient than having a sail boat.

Obviously it is also hard to prove the efficiency of your system on a boat, rather than in a static load situation, even when comparing it to a rival system. Afterall, not everyone sails the same boat at the same speed.

Having said that, you may want to check out the Ocean Twins 36 catamaran that was built in Millbrook, UK and featured a 12m/40ft dia windmill driving a propellor. I have sailed against that boat and it did sail directly into the wind at 6knots vmg, so was better than the sail rigged boat

You might also want to check out the Ecocat solar panel powered day charter catamaran, also built in Millbrook

Boats are not just moving vehicles. They have to be practical as well. The 40ft windmill blades were very scary for the crew, even though the tip was over 6ft above deck. And coming alongside was also fraught with difficulties - never mind drying out

The weight of the windmill might be greater than a sail rig, which will have serious consequences for pitching etc

So I tend to agree with SamSam's last comment

Richard Woods of Woods Designs

www.sailingcatamarans.com

 

The observations about efficiency are spot on, and one of the biggest problems to overcome with such a project.

For example, a 25m diameter wind turbine can generate, at the turbine hub, around 2.5 to maybe 2.8kW in a 10 kt relative wind (i.e the wind flowing through the turbine disc), despite the power in the wind at this point being around 6kW or so.

The turbine electrical power output might be between 2.1 and 2.4 kW under these conditions, and the mechanical power output at the propeller shaft (allowing for controller and motor losses) might be only around 1.8 to 2kW.

It's difficult to build a wind turbine that can extract more than around 45% or so of the power from the wind flowing through it, especially as you want it to work well over a wide range of wind speeds, Similarly, it's hard to get better than about 85% efficiency from either the turbine electrical generator or the electric motor at the propeller shaft.

It's certainly an interesting project, though, and one where the efficiency issues become somewhat less important in terms of design limitations as you increase the scale of the boat. My guess is that the overall efficiency would be somewhat similar to a conventional sailing boat, but without the disadvantages associated with only being able to sail with the wind abeam or astern.

I have a variable pitch 6ft diameter carbon fibre blade set that I keep meaning to experiment with on a small boat, but as always other projects seem to get in the way!

 

I recall the last Vendee race included Team Acciona, which had a yacht powered by sail (of course), but also included wind, hydro & solar power. The yacht did quite well overall, but dropped from the race after its keel failed and the boat capsized. No fault of the power system though!

http://www.tecnotalasa.com/Vendee_Globe_Acciona_EcoPowered_en.html



In my opinion the power system for this yacht serves as a good benchmark for future designs. The varied power systems provide a redundant source of power. So long as the sun is shining (solar), the wind blowing (wind turbine)and boat moving (hydro generators) you've got power. Maintaining and balancing all of those renewable power sources is your holy grail.

Good luck with your project!

 

Looks like they had a hydrogen fuel cell as back-up/emergency power as well.

 

I don't think the OP has any plans to offer a power source for boats, but wants a boat powered by their 'new design' as a gimmick to sell the idea of their new design wind turbine. A wind turbine powered boat is not practical, there would be no market for one. Unless the OP has a revolutionary design that would make it practical for boats, and also not butt ugly, I just wonder what it proves to power a boat with it. But, maybe it doesn't have to prove anything and only has to catch the eye and grab attention.

 

As I have previously stated in other threads, I think a wind turbine powered boat does have potential for one specific application.

This is for use in a cruising application where the system is coupled with a decent amount of energy storage and the anticipated trips between the "stop and charge" periods is either small or you are not in a real hurry.

With a good highly automated wind turbine and a decent power storage scheme, the objectives would be to

1. Allow living comfortably at anchor with no shore power.
   
2. When it is time to move, you pull up anchor and take off using either stored power along with the ongoing turbine generated power.

The actual turbine is probably an easy part to figure out, but getting it to do what you really want is not so easy. In order to make it work well, the turbine needs to be able to self align with the wind, self adjust for optimum rotating speed and auto feather as required if the wind is providing more power than you can use. This kind of technology is not un-heard of (again see the posts by Ingmar Hendriks posting as SpiritAmsterdam discussed in my earlier post) but is not simple or "off the shelf" at this time.

The generator and prop drive motor both probably need to be much better than the typical 85% efficiency. 90% - 95% is probably achievable, but not currently available as "off the shelf" items in the sizes required. As such, they are not high volume items that are cost effective.

Storage has gotten much better and continues to improve. However, items such as cost, life expectancy and environmental considerations are all continuing concerns.

And then there are the power conversion and transmission devices. This is an area where reasonable technology is probably not out of reach, but it probably will require the right smart guy to find all the right pieces that can be assembled and made to work together.

The above seems like a nice list of challenges. Probably a bit much for any small team to work out.

It is a shame that we can not break them up and get a bunch of different teams (possibly university / grad student kind of efforts) to work on the different pieces as advancing the technology for each piece has significant merit. However, the real plus would in getting enough progress on all but one such that there would be a payoff for some one to take on the issue that remains.

 

Besides efficiency, a big problem with rotating machinery is gyroscopic moments in a seaway. Bradshaw says on his website,

I think the issues Bradshaw talks about are fundamental to any rotor rig. An efficient rotor needs to have a large swept area, whether it has a horizontal axis or a vertical axis. This can be verified using momentum theory - it is more efficient to slow a large volume of air a little bit than it is to slow a small volume of air by a lot. Pitching motions will cause yawing (horizontal axis) or rolling moments (vertical axis), and rolling motions will cause pitching or yawing moments from the rotor. The result is dynamic loading on the support structure and control mechanisms, leading to as many fatigue cycles as there are waves on the ocean.

It's not an insurmountable problem, but can be a design driver. Aluminum is has poor fatigue resistance, so is probably not a good choice of material. A catamaran hull form is probably a good idea from the standpoint of minimizing the rolling motion.

It would be an interesting question as to whether it is better to have one large rotor or several smaller rotors comprising the same total swept area. The smaller rotors mean more parts and failure modes, but they might be more manageable and provide some redundancy for more graceful degradation due to failures. Contra-rotating rotors would also cancel out some of the gyroscopic effects. Smaller rotors might be easier to confine within the footprint of the deck, which would make the boat more friendly when tied to a dock.

And then there's the issue of upwind vs downwind sailing. On a reach, a rotor can operate as a rotary sail (like an autogyro rotor) without being coupled to anything in the water other than a fixed hydrofoil (keel). Downwind, it may be better to use it as an air propeller driven by a water turbine. Variable pitch and possibly variable twist would be important to shifting modes.

 

I just think powering a boat with a wind turbine would be a poor and expensive way to show the merits of a 'new design' over what's already available.

 

The main issues have been well covered above.
The issue that comes to my mind is what type of turbine you have developed and how that will relate to the design, if it is a horizontal axis turbine with the generator up high my guess is you will need height to obtain clean airflow and hence weight aloft and a larger craft.
If however it is a vertical axis turbine with the generater down low and is omnidirectional then you have a better chance of operating with a lower "mast" and hence less weight aloft and a smaller (cheaper) craft.
So cough, which is it ?

 

OP,
I suspect you are underestimating the challenges of your proposal if your wind turbine is similar to the current industry. If your design is not much more robust than typical land units and is not designed for marine environment this could easily turn into an embarrassment. The project assumes that you have great capability but need to draw attention to that fact. My gut feel is that the task is more demanding than the target audience appreciates.

I recommend you characterize your turbine and do some virtual prototyping of loads due to pitching and rolling. Any of the NAs that use CAD can characterize their designs for moment of inertia and force/deflection floating. Add the inertia and gyroscope properties of your turbine along with the sea states likely at differing wind levels and you will get a good indication of what you are up against. Personalty I doubt it is within the factors of safety of your production unit if it is for fixed terrestrial use.

 

From a marketing point of view, an emerging segment in the workboat field are vessels designed to service offshore wind farms. Again, from a marketing point of view, what better vessel to provide this service than one powered by...a wind turbine? :idea: