the top of a current Waszp section? We did that – on both front and back. And the front one was better than the carbon Mach 2 one. SH: The key point? AM: The key was to try to make this work as a retractable foil. But the front wing-foil one was significantly better that the carbon one – then I started doing some torsional measurements and aluminium was way stiffer torsionally – even though it was a similar flexibility. Aluminium has no ‘direction’ whereas with carbon you have to think how much torsional stiffness you are putting in so you tend towards stiffness. It was a bigger section – and it was faster… SH: And the combination you have decided to run with is, what? AM: Staying with the verticals… I wanted to have a small inner section, and a sleeve that went over it which fitted into our current rudder box, and that all slides up. If you look at the video on our website, that is where we have ended up. From all the experiments we did with various sections some were too draggy, or not stiff enough. I knew the stiffness and length we needed on the rudder, so we kept shortening it until we noticed the difference, then went back a tiny bit. It was also tricky with the longer test rudders, as it was difficult launching in waves – and so it was about getting it right, without compromise. It is now almost 60mm longer. SH: When did it become available and how was it received? AM:We can’t make enough rudders! The first batch were available for the Waszp Australian Championships in January. The bulb area thingy in the joint connecting area needs to be sub-0.1mm accurate, and so some very fine tolerances. We have 600 pre-orders, and some people are irate that the Australians got their first. Sorry, guys… and the rudder comes out at under AUD$1,000 – that is both the vertical and horizontal, so under £500. SH: Next? AM:We are having discussions with World Sailing to try to become an international class. We are trying to navigate the terms we want – we may get there, but I won’t compromise and we will stay agile. A lot of countries need us in World Sailing to be eligible for funding from national associations. So it is about educating why we have written our rules the way we have, and how we can change our rules quickly. Agile but smart. And we’re not giving that away. Blue Robinson


USA Back to school The latest 25th edition of the Chesapeake Sailing Yacht Symposium at the US Naval Academy in Annapolis prompted a perhaps overdue introspective look at how our sport has evolved in design and tech- nology since the inaugural CSYS in 1974. For those of us who try to pay close attention to how science and technology influences our sport, this event has always offered a welcome intellectual recharge. In its inaugural edition in 1974, it’s interesting to note the range


of topics and who was presenting them. Out of 12 papers, five involved rating rules, timed as this was at the dawn of the new IOR rating system. Daniel D Strohmeier’s paper entitled simply Yacht Rating started with a timeless quote from Nat Herreshoff: ‘Yacht measurement and its necessary companion, time allowances, form the spice of the sport of yachting and cannot be overlooked.’ Indeed this is still true, yet Strohmeier concluded his work by


stating, ‘The complex laws of yacht behaviour preclude the prob- ability of a perfect handicapping system under which skill alone will determine the winner among dissimilar yachts.’ Hmm… 50 years later the struggle to disprove this adage goes on. Olin Stephens presented his thoughts on the importance of


Measurement Parameters of the IOR Rule, while Dave Pedrick spoke on The Performance of Sailing Yachts in Oblique Seas, and in a pre- monition of the distant future there were already studies on foiling control by WS Bradfield and the Aerodynamics of High Performance Wing Sails, presented by Otto Scherer. Scroll ahead 11 years to the seventh CSYS and there was an interesting mix of experimental, analytical and more subjective papers. Among them was a paper from JA Keuning on five keel-hull configurations studied in the test tank at Delft. Keuning’s compre- hensive work in this field provided the test tank data that still forms the basis of most hydro models in modern VPPs; only in recent years has this work been more fully updated as hull shapes have


evolved to planing forms and curved foiling appendages. It was also 11 years ago that Peter van Oossanen described the


development of the breakthrough America’s Cup-winning design of Australia II, giving an account of the design process and technology used under the direction of Ben Lexcen at the Netherlands Ship Model Basin in Wageningen. Another paper focused on stress loads on 12 Metre transverse


and longitudinal framing structures, presented by the design team from the YC Costa Smeralda’s Azzurra challenge at that same 1983 America’s Cup. They used calculations from classical naval archi- tecture and compared them to results using the emerging new field of Finite Element Analysis (FEA). Among the authors were designer Andrea Vallicelli, along with Bruno Finzi and Nicola Sironi, two of the most formidable forces driving the development of ORC. These and other technical papers were in contrast to what must


have been an entertaining presentation by Ken Court which was described as a follow-up to his sea stories presented in the second CSYS in 1975 of a four-year cruise around the world on a 28ft ketch. ‘The 1975 paper reflected my background as a naval architect, combined with my experience as a sailor,’ he said. ‘I told of things I learned from others. I analysed log data, presented photo graphs, drawings and tables, and wrote a series of “yarns” such as sailors spin about their travels.’ No doubt this was a welcome break from endless slides of graphs and differential equations. After a lot of focus on the ‘new’ IACC America’s Cup class the


12th edition of CSYS remained heavy on technical presentations but now with some content around the design and build of non-IACC yachts! For example, with carbon spars becoming more common in the mid-1990s, Paul Miller presented a timely paper entitled Design Criteria for Composite Masts. Brian Jones spoke about the design, construction and performance of his 27ft MORC boat Problem Child (still racing locally in Annapolis), and Ken Court returned to speak about the design of an Open Class BOC 60. Scroll forward 16 years to the 20th CSYS in 2011 and, while day


one is still heavy on technical and theoretical content, it is being presented this time not by AC programmes but by undergraduate and graduate students and their faculty advisors, along with tech- nicians from facilities that offer bespoke research services to sail- makers, designers and the like. Studies presented in this edition also focused on topics such as FEA optimisations for composite struc- tures, free-surface effects on bulb keels, RANS flow codes, etc. There were also papers to appeal to a more general audience,


such as Rob Ranzenbach and Bill Lasher’s To Twist, or Not to Twist? – A Scientific Attempt to Understand What We Think We Already Know About Sail Trim. Their conclusions were interesting: suggesting that it is indeed (as all Kiwis know!) more efficient to reduce power by keeping the main sheeted hard and lowering the traveller than by keeping the traveller up and easing the sheet. They concluded that the lift distributions for all sail trim combinations studied were underloaded near the masthead relative to an elliptic distribution, and that any additional twist in the main increases the induced drag, and that the difference in performance is almost entirely attributable to differences in the induced drag. Who knew. Scroll forward to this year’s 25th CSYS and the format is broadly


the same – ranging from highly technical papers on computational methods to help, for example, unravel the complex CFD modelling of wave influences on offshore yacht VPPs, yet tempered with some seat-of-the-pants relevancy. An example of the latter was New Zealand-based designer and builder Rob Shaw’s engaging presen- tation on how his intuitive approach to modifications in hull, rig and sail designs has upgraded the performance in existing sportboats without the need for complex analysis methods at all! Another feature of the 25th CSYS was the high percentage of


the audience who were students, from the US and elsewhere, who seemed fully engaged and enthusiastic about wanting to tackle the neverending challenge of scientific problem-solving in sailing. It is great to see this high level of enthusiasm, especially for the US students whose future support in academic research seems at risk given the toxicities in our current political climate. A now triennial event that for all its ups and downs continues


to provide an invaluable infusion of thought energy to the sport. Dobbs Davis


q SEAHORSE 31


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