Feb 18, 2014

A-Class Worlds: Ashby Rudder setup

Last week Dario Valenza from Paradox told us about the L foil Ashby and the part of the TNZ was using. Worth posting it again as it was the winning rudder setup on the Dnas. Daggers were standard factory J shape.
Report sent by Dario Valenza / Carbonic Boats:


"Hello from Takapuna, It is certainly a very interesting regatta with a lot of diverse and good ideas being tested by many in the great spirit of the class.
As you may have seen, Glenn Ashby, Peter Burling, Blair Tuke and Ray Davies have fitted rudders, stocks and gudgeon systems from the Paradox V2 by
Carbonicboats. To clarify, this new setup has the angle between the vertical and horizontal at

90 degrees (Mayfly and V1 Paradox had a more open angle). No coupling is sought between sideforce and vertical lift.

Another crucial characteristic is a custom high-speed section optimised for the application.
The section and plan form are designed by Dario Valenza and construction is by Tim Makepeace using tools machined by Carbonicboats.

The collaboration with the ETNZ sailors came about at the last minute when

the detailing and potential of the Paradox V2 were noticed at the AUS Nationals in early January.
In the lead up to the Worlds Carbonicboats prototyped some experimental adjustment systems and helped to develop the geometry and settings required to prolong the periods of 'damped' flight that offer some significant gains.

T rudders were also tested. They seem to provide a bit more damping in strong conditions but the Ls have less drag around the course.

We also have two identical prototype boats at the Worlds. Our development has been slower than ideal due to issues with contract builders, but, now that we have extremely competent guys like Tim on the team, we are now moving all production in-house and we intend to persevere in developing a fast, beautiful and affordable production A Class cat.

- CSN: How are the Ls rudders performing in calm weather though? Any test yet or we have to wait for racing?
Most testing was in some breeze. Forecast for racing is light so we will see. For sure the L has less drag than a T or + Winglet because there is only one free end in the flow so basically no junction drag. It is just like having a deeper rudder, if you 'unfolded' the foil and made it straight down with the same area... Also with the ALS we can put the vertical rudder blade further outboard. This moves it away from the wake of the foils because with leeway the wake passes by the inboard edge of the transom.

Will keep you posted on developments here and at home."

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