Wing sailed catamaran

Hi everyone,

I’ve often looked up information on this forum, and now finally i registered, too.
I am studying Industrial Design and i've already made some designs for motor- and sailingyachts. Right now I’m working on my diploma, which is a 30-40 m sailing catamaran. Basically it’s a concept for a toy for rich people. The concept is to work with asymmetrical (cambered) wing sails on both sides. The ones which aren’t in use are supposed to be flapped in or onto the hull. I’ve made a lot of research but actually i’m still not an expert on aerodynamics. Racing catamarans with wing sails have symmetrical wings with complex constructions of flaps and stuff. Actually I’m a little overstrained with what would make sense and what could be useful, since the owner should not need a diploma to trim the sails. But still the whole thing should work well even though it won’t have to win any regattas since it’s supposed to be a cruising catamaran.
I’m not an engineer - I’m more doing the concept and design part. A problem is also that I have tons of airfoil data but just very little on sails, so that I’m not really able to compare anything. Thanks to Marchaj I have some basic knowledge, but still this is not enough to say how my wing sail should exacly look like.

I would be really glad if someone could give me some hints or ideas.
I’m really interested in your opinion!

Thanks!

 

The simple answer is, if you dont need to win races, then it doesnt matter what shape it is. You can go crazy with interesting shapes, and you will be hard pressed not to make something that will make the boat move - especially a light hull like a catamaran. eg the Crab Claw sails of hawaian canoes,

Some years ago, a mechanical wind sail was designed that was controlled by computer. To take the hard work out of optimising sail orientation and operation, you could probably develop a simple automated control system that would provide enough ease of use for the novice captain, without having to make the boat perform like an F15.

probably the only real constraint will be to keep the centre of effort of the sails from making the boat unstearable, and that isnt too hard to work out on a catamaran.

 

German 'sailing' technology

Being from Germany I assume you are familiar with a few technologies associated with Germay that that are receiving quite a bit of attention in the boating world lately??

Dynarig (modern square rig)
SkySails (kite-assisted vessel)

..if you utilize the 'search button' on this forum you will find considerable number of reference discussions about these two subjects (many be me). Hopefully I will find a client for this Dynarig motorsailer catamaran. But new ideas are hard to sell conservative sailors.

do a search for 'bi-plane' or 'bi-pod' rigs

 

thanks for you opinions!

@rwatson:
you are right, i already thought about this too, as I don't want to win races anyway.
And since I wanted the flaps to be controlled by electrical motors anyway, why not use a computer to do the exact trim (in case there is a possibility to put sensors on the surface of the profile which can measure the air pressure)

@brian eiland:
I'm familiar with those rigs. You did nice work on your dynarig!
I think that design can help to sell new ideas. With a good design you can sell all the emotion and new technology better. You can make things look like, as if they really work (even if they don't) If a new technology looks really cool, just like a "must have" I'm sure you can even sell it to some really conservative sailors. For example I think, that the dynarig of the Maltese Falcon looks really cool! And on Kite-Sailing some other Designers have already made good work. I've attached two pictures. But those are also still concepts.

 

I think the controlling computer can be quite simple. I have though about it for radio controlled yachts, and I think all you need for inputs is-.
1) Wind speed
2) Boat Speed
3) Heel
4) Wind relative angle.
5) Preferred Boat Speed * Input by the Operator as a)Zero, b)Maximum or c)1/3, d) 2/3 efficiency*

The internal logic will then apply the predefined controls to whatever situation is required.

I think that very fine inputs like air pressure detectors, gear positioning detectors would be useful, depending on the trickiness of the gear.

If the coventional bermudan rig was in use - then you could do what model yachts do and make everything self tacking and self vanging to reduce complexity.

The ultimate self controlling rig is the Flettner Rotor sail, requiring 2 controls - direction (clockwise, anticlockwise) , and speed of motor. The old metal rotor sails were never very aesthetic, but with see thru fabrics, maybe a good looking version is possible

 

Newbee,

I have worked in aerodyanics and aircraft design, and have been around sailboats most of my adult life. I am not sure there is a practical application for your concept.

If this is supposed to be a toy for rich people, why bother with a wing/sail? Just put a motor in it and forget the sail. It seems to me if the customer can afford an expensive toy, they will likely want something that looks like a traditional sail boat, or they would not want a sail boat at all.

I am not attacking your idea as a concept (I always enjoy seeing new ideas and inventions), it is only that there will likely not be a very large market for it. It has to be a viable product to be of practical value. Unfortunately these are the facts of the boating market.

Other than recreation there are not a lot of practical applications for a sail boat. So it is either for sport or for enjoying the way it looks (i.e. the prestige of owning a classic sailboat), neither of which a unconventional wing/sail cat will satisfy.

In my observation most wealthy yacht owners buy them because they want their 'toy' to look like a traditional sailboat. So either it has to look traditional, or it has to offer some significant advantage over a much less troublesome motor yacht.

I am not a naysayer, but you have to focus your creative talents in areas where there is a viable market for them. As a rule, before embarking on any new design concept the first question to ask, as objectively as possible, is "why built it?" Would anyone want it? If you want to build it for yourself, be satisfied with something small enough that you can afford and experiment with for fun. Otherwise it would just be a wast time and talent.

What you might consider is making a traditional looking sailing yacht easier to sail and operate by automating the sail controls. This can be done with an on-board computer that will continually teak and warp the sail and assist the captain in steering it to make optimal speed and distance for the various tacks and conditions. It is conceptually possible to install servos or tensioning devices within the mast, or the sail itself, to adjust the trim on the sail. But the whole rig has to look like a conventional sloop rig sail. That might have a market, a rick guy can look like he knows what he is doing without having to learn all the details of operating a sailboat.

Good luck.

 

KISS! Just to let you know that most designs available on the market will do a decent job. If you want to be on the edge look at Reynolds that addapted WindSurfing sails to cats. WindSurfers redesign their sails every year and adapt their boards to the new design. They also use a lot of composites which most companies don't manufacture very well (even for airplanes).

 

@rwatson: a already thought about Flettner in the beginning of the project, but actually I couldn't figure a out a way this could somehow look dynamic... I think such a computer would be the best solution, as guys like such things as toys, too. i don't really know if the computer will need input on heel, actually i suppose the cruising catamaran with 40m and approx. 100t displacement won't heel too much...

@petros
interesting suggestion. Probably you are right. I've already designed just motoryachts, but actually I think it's a little boring. I'm a sailor and could never imagine myself buying a motoryacht. However this is my diploma and probably the last chance in my life to do things I like. Afterwards I will always do, what the client wants ;-) And well I still hope that you just need to present rich people a really cool design and they'll like it as well. This project is just something I really want to do, also because it's a quite interesting design work, it doesn't matter if I can't sell the draft.

@chicago drifter
I've made a lot of research on windsurfing already and learned some really interesting things on that. But thanks for the suggestion.