“The Box” our first boat and test platform.
The rudder worked very well in all ranges as long as the angle of attack wasn’t to high, in that case it was terrible and stalled easily.
I think some of this was chord thickness (only 5mm) and also flexing.
This boat was tricky to sail, SUPER fast upwind and good running but not a great reaching performer.
Thank you John,
ClaudioD
To me, the rudder is way too small. The aspect ratio is too high. There is not enough area. As a result you have to turn the rudder more, increasing the angle of attack and it stalls. I would guestimate a width of about 3 inches at its current length. Also a very thin (5%) thickness is more prone to stall than a 7 or 8% blade. I think a larger, fatter rudder will give more control and may significantly improve reaching performance by reducing the drag that keeps happening as the current rudder stalls. Control would also improve (less twitchy) if the rudder were moved further back, increasing the distance between the fin and rudder.
On a separate theme, I don’t understand why the rig and fin are so far forward. If they were more centered, the COE would be further back and there would be more buoyancy forward of COE to resist nose diving in stronger winds.
John
The rudder was plenty big for the setup. The stall issues had more to do with the the balance of the sailplan when reaching than the size of the foil. Our new boats (shown earlier in the thread) actually reach much better than “The Box” with a rudder that has 10% less area.
“The Box” has a rig and fin position that is fairly far forward due to where the center of buoyancy is. We were testing a hull that would move the bow wave as far forward as possible with the hull shape, making it a very “long” boat. In the simplest sense we had to support the weight, since the volume was very far forward the weight also needed to be in order to get it to float correctly.
Our new design running in medium conditions:
I remember John one of your first video with the “box” and I was really impress about the stability with strong winds and no “nose down” tendency.
I do not recall the tread, will be interesting to propose it again !
ClaudioD
PS: I found it, http://www.youtube.com/watch?v=yoVGA5NdyNQ
Hi John,
My point is that it is not the surface area of the rudder that is the issue, it is the aspect ratio. A rudder of 12 inches by 4 inches has 48 sq in of area and a 24 inch by 2 inch also. But the shorter wider rudder will be less prone to stalling.
John
a different observation from the pics is that the jib foot looks quite tight on Alinghi compared to Prada which looks deeper and more powerful, any reason for this ? a different jib cut ?
G.
Good eye, yes the sails were different. “Prada” had a fuller jib & main than “Alinghi”, mostly for testing purposes.
fair enough 
A little video from Yesterday, 10-12 knots “B” size sails.
gallery of some 2 boats testing, have a look 
http://s1249.beta.photobucket.com/user/carbonboats/library/2m%20AC%20Sport%20Scale%20%202012
Hi John - I get a “broken link” to your video.
Dick
HMM thanks for the heads up, not sure why I just clicked it and it played.
Try this one:
http://s5.beta.photobucket.com/user/evelyn32/media/IMG_0233.mp4.html
Thanks John - that one seemed to work for me.
Dick
Cool. Questions, comments, thoughts welcome
linked worked ok for me - looks great. Though not sure if it was because you didn’t stay long on port or the angle of the “waves” on the hull but it looked the boat was more at ease on the std tack then on Port ?
Have to say though - SANTA can I have one for Xmas - been a good boy this year I promise !!! 
looks great !
G.
don’t mean to be off topic but I see on your video that you’re using the T6J futaba system - how do you find it ?
2 weeks ago I had the first glitch with my spektrum system : lost control of the boat at what didn’t seem a far distance. Sail regularly at that distance before but twice I lost control with the winch going in safe mode and no response to the rudder. Second one was just few metres away from me. :mad::mad::mad::mad: and of course it was during the race I was leading after a mixed day.
Had the system for c5 years now, working each time like clockwork. not sure what happens - heard since that some people suffered from same issue but on more regular occasions…
G.
Thank you we’re really happy with the progress of the project.
The waves were easier on STB for sure, and to be honest I was trying to drive and hold the iphone so my helming wasn’t spot on…
I’d be happy to make you one for Christmas…! We actually just wrapped one up for a new owner last week.
We hope to have 6- 8 out sailing this summer, it would be great to have the One Design take off.
Since we have very few boats our size and speed to race I take the boat over to lineup with the 420 frostbite fleet.
We found that in light conditions they are dead even upwind. They let us start with them in a race and we rounded the top mark overlapped for 3rd!
As for the radio we’ve had good luck (knock on wood) I do run the 2 antennas up and out of the hatch, not sure if that helps.
I am always a little worried since the entire boat s carbon.
interesting actually to race them against dinghies as upwind should be fun - I gather that downwind once they put the kite up they leave you in their wake ?
just out of curiosity do you know what speed you get upwind in 10-12 knots of wind and on a reach ?
cheers, keep it coming
G.