Hi Dick
a sketch will help.
Rigid sail not allowed on M.
Some good beers and a book of ideas !!!
Actually 32°C outside. Thank to AC.
Ciao
Claudio
Claudio
Not a great sketch - but should work. From previous discussions “somewhere” on the web. 
I haven’t posted for a couple of days as this has picqued my interest and I’ve been busy with AutoCAD.
I guess at some point I’m gonna have to put this stuff into practice and decide whether to go wingmast or wingsail, at least initially. At the moment the temptation is to be really adventurous and go with the solid wingsail.
I’ve sketched out a design for a wingsail to equip my 2metre catamaran - I’m being conservative to start with, conscious of the fact that I don’t know how to sail a wingsail, and have a heigth of 1.8metres, a foot of around 0.6metres and top of around 0.3metres - total area of around 0.9sq metres.
Other considerations are how to control it, it feels as though it needs something more direct than a conventional sheeting arrangement.
Ray
Of course, there other possibilities other than wing masts or wingsails.
One of the reasons we’re exploring these is to minimise the inefficiencies of a conventional mast arrangement. If you talk to fullsize boat sailors they’ll tell you about how a boat powers up when you deploy the headsail - they generate more drive than the main stuck behind its pole. One of the reasons for this is that their entry is so small, essentially just the firestay, eliminating all the mast issues.
So why not just use headsails, like this…
http://runningtideyachts.com/sail/
Of course its never that simple as you still have the drag of the pole and its bracing but at least the sails work more efficiently - in principle!
Ray
A little OT :
I was developping this Cat boat some 6-7 years ago.
When I presented the project, the simple objection was : 'If you don’t see such boat around is because they do not sail well ", etc…
Since that times, some design like that, begin to appear around , one day, they will 50% of all… Fashion take time to change !
This is a very old design born around 1924 , a long story…
The much regretted Phil Bolger, passed away very recently, described this design in one of his books, and there is when I picked up the idea.
It is my intention to describe the construction of one boat like the CD-CAT as I did for the AC33 or CD65.
For the moment observe these pictures just taken a couple of hours before the boom break !
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I should open a new discussion, but there is still a lot to says about Mast, Wing , Rotating Mast, etc.
Ciao
Claudio
:scared: Boy - you guys are keeping me busy - finding all that old stuff I put away a few (???) years ago.
My apologies to whomever sent this to me, but an interesting concept using a single, unstayed mast as leading edge, but with a wire luff for the second foil (sail).
I have no idea how ( or if) it would work, but recall this appeared during an old discussion on masts and sails.
Ray -
here are a couple of photos of a 2 meter cat ( circa about 2002) built by French sailor Jean Margail (WATER RESIST) in which he used a single element solid wing, that he only controlled angle of attack. Notice how short the wing is compared to what would be “normal” for a soft-sail 2 Meter boat.
I’m not sure of construction, but at times when I look at the various photos he sent me, the wing almost looks like “foam board” kids use for school projects. Glue to a round carbon tube (leading edge), knock out some holes to reduce the weight, cover with clear sticky film and give it a try.
Claudio - note in one of the photos, all shrouds and forestays (total of 4) lead to a small tab mast hound sticking slightly forward of leading edge of mast, which allows wing to rotate into the apparent wind.
Claudio, thanks for sharing your cat boat project, really interesting. Fashion is a big inhibitor to development, the ‘me too’ mentality, but the rule makers also take a lot of the responsibility as many class rules restrict rigs to those that are already known and which were possible technically when the rules were drawn up.
Dick, thanks for the wingsail images - clearly the rig works! I have also considered a single element design as it keeps things very simple to start with, though there do seem to be distinct advantages to multi-element (and disadvantages - weight). It also helps to address some of the questions I have about how big the rig should be as I would guess that one to be a little smaller than my design, though it’s difficult to gauge the wind speed its sailing in.
Ray
The Sailing different :
The Past : …Once there was a “Stars & Stripes”
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The Present :
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The Future
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Claudio
Ray - I have a few photos of that 2 Meter cat in various positions of disarray! (capsize)
Claudio - thanks for posting the various stages of development.
I do want to call your attention to the Stars & Stripes catamaran photo. See how far forward the leading edge of the wingsail is compared to the location of the point of rotation? The wing set on a ball located in the middle of the front cross beam, so there is quite a bit of sail area forward of rotation point to help the wing rotate more easily. In fact, the mainsheet probably only handles the maximum angle of attack, with a secondary line that handles the camber adjustment. By keeping the wing (or mast) forward of the rotation centerline, it should rotate much more easily than if mounted directly at the leading edge of sail/mast. Kind of like a balanced rudder which requires very little deflection to cause steering to take place.
Now I really have to give some attention to the “future” boat ! 
This design is sitting in my desk since ages. Is a Cat with dual jib. The Stays replace the mast. The pseudo balestron help keeping the CE close to the center line during running.
One day …meanwhile if someone like to try !!
This design came out before the Tackon 40
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Claudio
Here’s another interesting development, back to square riggers, but with a twist - literally, it has rotating masts.
http://www.symaltesefalcon.com/photos.asp
check out the photo’s about half way down.
http://www.symaltesefalcon.com/design.asp
Ray
Hi Ray -
I dug out a wing mast made for my F48/Mini40 size multihull. Basically spruce core, covered by shaped foam and then epoxy/glass. Was originally designed for a cat platform. Forestay was a single short “pigtail” from mast, splitting into two front forestays (one to each bow).
Drawing shows approximate location for shrouds and forestay - but mast was pretty “soft” so diamond wires would be necessary to provide added side stiffness. Mast crane at top was left longer than needed until final mainsail shape decided. Originally it was to be rigged as a uni-rig only. Since it was designed for a 1.2 meter multihull, perhaps you can use dimensions to further your thoughts on wing or mast design. Original thought was to use a double-luff main to wrap around mast - but use very soft material instead of still material to better take on the shape as mast rotated.
On the practicalities of constructing wingsails, where weight reduction without compromising strength will be important I’ve been pondering different approaches to constructing the ‘wing’ ribs.
The obvious approach is to get them laser cut from lite-ply, and that is how I’ll start, but I’ve been wondering about a different approach using carbon fibre/epoxy and whether it would result in a stronger and/or lighter rib.
My thinking is to get the layout of the rib profile and suitable X bracing CNC routed into a suitable base material so that you end up with grooves (say 3mm deep and 2mm wide) in the shape of the finished rib. Having applied a suitable mould release agent I would then lay wetted-out carbon fibre tow into the grooves. Then apply peel-ply, breather fabric and a vacuum to consolidate and suck out the surplus epoxy. Problems I can see are that it will be labour intensive and getting the cured rib out of the mould (grooves) might be interesting (but doable, use a flexible base material), benefits would seem to be, potentially, strength and lightness. The main question I have is ‘how much carbon tow?’
When I can I’ll try an experiment but in the meantime I would welcome any pointers/advice? Surely someone must have done this already?
Ray
Ray -
what about buying carbon plate of minimum thickness and sending it out to have ribs laser-cut? While it might cost a bit more, you eliminate a lot of personal labor time tring to lay them up. You could send a CAD drawing along with 1 or 2 sheets of thin carbon and in a few days (and exchange of money :mad: ) have the ribs ready to lay up tot he carbon tube.
Just a thought.
Dick, that is a possibility, though I haven’t seen anyone this side of the pond saying they’ll lasercut carbon sheet.
My reasoning behind the appraoch I described to to get all the carbon fibres aligned to get the most strength where it is needed.
You mention a carbon tube, I would use this approach for a simple single element wing but for a dual element you need a hinge arrangement and I’ve got some other ideas for that on the basis that it’s good for weight reduction if you can get the same component to perfrom multiple roles in the structure - I’ll return to that in the future.
Ray
Stimulated by this tread I decided to recover an old idea and removing some dust.
It consist to increase the sail effinciecy of a Class M taking into consideration the Rules limitations or about in view of potential other applications. The basic idea is the “dual luff” where the main top shall not be larger of 40mm mast included.
Borrowing the airplane wing tecniques, I draw a sail plan rather different from the usual ones where the main is actually covering 85% of the total surface while the jib is reduced at 15% and should act , according to my fantasy, as a sort of Slat. The Rig is a swing-rig
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I look to the papers of TSpeer, without understanding very much, but I collected a drawing as the top one here. I drawn a couple of profiles one a little “fat” and the other rather “slim” and oriented to an incidence angle of 10° and 13° and observing the overall geometries and immagining the possible air pockets or separation bubbles, etc.
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It may be wrong, but the figure E appears to be the one wich has less “pocket” and “separation bubble” here a couple of pictures from a mockup, I used also an air blower to force the curved shape of the ribbon simulating the main.
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with retaining Pin
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The problem I have now is the construction of the ‘sleeve’ or ‘fairing’ that should be 200cm tall, 4cm wide at the top and 11cm wide at the bottom.
I’m preparing the wooden mockup on wich I shall later laminate a semi-rigid FBG fairing.
The longitudinal shape is also conical and thick 15mm at the base and 11mm at the top. 0.2% slope only !!!
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That’s all for now ! Any comments ?
Thanls
Claudio
These batten arrangements look just like the ones being used on Formula class windsurfer sails.
http://www.formulawindsurfing.org/viewer.php?f=090310&id=12
and one cam design:
http://rsracing.neilpryde.com/index.php?option=com_content&task=view&id=29&Itemid=41
Use batten tension to get the cam to push the sail to leeward and reduce the pocket on the leeward side.
The tension would not work on a model sail as it would prevent the sail from “flopping over” when tacked. On boards, the sailor can tack, then pump the sail to get it to pop over.
Hew,
I don’t think my design is similar to what you says.
In Class M only 4 battens are permitted and limited to 10cm only.
In my approach no battens will be used, only a long sleeve and one sail mylar cloth.
Cheers
Claudio
PS: to complete my answer this is what could be the main sail set up principle
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