A Winning Strategy for Volvo 70 Design:

Saturday, 20 December 2003

Open 60 swing keel and daggerboard utilising CFD

The sound of the chainsaws ripping through lead echoed across the basin, cutting through the quiet of that December dawn one Saturday in 1986 in Western Australia. The azure-blue Indian Ocean stretched out beyond the quay. Inside the boat shed the designers of the gunsmoke-blue Twelve-meter Stars & Stripes were taking a calculated risk, reconfiguring the keel for the fight of her life against a remarkable piece of Kiwi ingenuity – Kiwi Magic. As with countless previous decisions, the designers of Stars & Stripes ’87 team were confident taking this chance because they were a team of naval architects, sailors, scientists, and engineers. From a historical perspective, the Stars & Stripes ‘87 program was arguably the first time the modern design team approach was implemented. US-55 went on to win the Finals against Kiwi Magic, and ultimately against Kookaburra to uproot the America’s Cup from the Royal Perth Yacht Club. Does such a design team philosophy provide an opportunity for a serious Volvo Ocean Race team to gain an advantage over their competitors who follow the more traditional design office approach? There are pro’s and con’s to each method, yet many of us who have been part of the design team approach over the years think there may be clear advantages for the Volvo Ocean Race competitors. The approach is simple, powerful, and efficient. It can be cost-effective and does not necessarily have to be big or expensive. It is project-oriented, “sailor-centric”, and “event-centric.” The method requires two or more yacht designers, and seeks to put together an elite unit geared for the client and for the event. The method has the experienced sailor as a design team member and as intelligent customer, and provides a growth environment for the junior sailors. In the larger teams, a design or team coordinator is a powerful addition. This approach is clearly not required for the majority of design projects, but maybe the perfect approach for many of the new Volvo Ocean Race Teams. My recent experiences with 140’ Mari Cha IV and a new-generation 90’ swing keel yacht Genuine Risk; as well as four successful America’s Cup programs.Stars & Stripes ’87, Stars & Stripes ’88 (catamaran), Team New Zealand ‘95, and Team New Zealand 2000 are good examples of the modern design team paradigm. Merf Owen, a principal in Owen-Clarke Design also believes there is an advantage to the design team approach. Merf and his group were responsible for Open 60 Kingfisher, Ecover and others. Owen-Clarke projects reflect tremendous attention to detail from start to finish of a project, including research, engineering, habitability and construction. After working together on various smaller projects, Merf and I realised that together we had an enormous amount of experience in swing-keel and moving-foil technology. So in June we formed a project design team specifically for this VOR. Our design team approach provides the Volvo contender with unique design tools, and the sum total experience of six America’s Cup’s, two Whitbread/Volvo races, a number of Open 60 projects such as Kingfisher and Ecover, and other recent projects such as Mari Cha IV and Genuine Risk. Early this year, we developed a research, design and construction program comprised of eleven tasks shown in Table 1. That table is an example of how to tailor a program for customers who may have different levels of funding and resources. It is divided into minimal, standard, and advanced levels of effort. Starting in June, we carried out three of these eleven tasks for a client who wanted a design headstart, even as he continued to evaluate the feasibility of an entry. In response, our team has developed a number of hull shapes, and along with a detailed weight study including results of preliminary structural design by SP Technologies, we have carried out performance predictions for systematic series of various concepts. We have fully worked through the mechanical systems, and further developed deck and sail handling systems after discussions with experienced Volvo sailors. Having done this work, we have isolated the key design factors that will separate the competitors on the racecourse. Table 1. Eleven task areas organized to provide “scalability” for the Volvo competitor 1 Concept/Planning/Strategy 2 Preliminary design 3 Preliminary Candidate Performance Studies 4 Rig/Sail Wind Tunnel Testing & Advanced Aerodynamics 5 Large scale (~ 6m) Tank Test for Appendages 6 Smaller Scale (~2.5 m) Tank Testing for Hulls 7 Appendage Wind Tunnel Testing and CFD of appendages 8 Final Performance Studies 9 Final Design and Engineering 10 Construction Monitor/Supervision 11 Launching and on-water development Some of the elements that characterise the modern design team approach are presented below. 1. More than one principal designer For the majority of racing yacht designs, a sole yacht designer or design office is ideal for the task. The design will be a manifestation of the individual experience, style and views of the designer or design office. It is a reasonable choice and is quite acceptable to may sponsors when the serious competitors are using the same design office, as has been the case in recent Volvo races. This approach might minimise the risk of a boat being significantly slower than her competitors, and so the team aspires to better navigation, routing, sails, sailors, and higher quality construction for an advantage. Sails have historically come from the same company, and many of the lightest, sturdiest hulls are produced by the same short list of boat builders. Looking for a design advantage, one approach we saw in the last Volvo Race was the Amer Sports team decision to build two boats, each designed by a separate and competing design office. But successful syndicates and owners are relying more and more on creating a single interactive, goal-oriented design team. In America’s Cup where the syndicates cannot use the same designers, winners like Alinghi, Team New Zealand, America3, and Stars & Stripes (’87,’88) all followed the modern design team paradigm. The concept not only brings together the strongest people in each area of expertise, it make the most potent use of financial resources. Successful and healthy teams bring together several designers with equal standing in the team, and ensure a dynamic and natural system of peer review. 2. Coordinate a more horizontal design team structure. A horizontal rather than hierarchical organizational structure is ideal for a successful design team as is the inclusion of a design coordinator. The traditional approach has the design office at the top of a hierarchically-structured design team, so when consultants are hired, for example to provide support and advice in computational fluid dynamics, model testing and experimentation, structures and rig, they will naturally report to the design office. In the design-team paradigm, consultants are cast into team members and participate in design meetings as a real part of the team. Although it may seem like a small difference, it is this difference that generates the most ideas, results in more efficient use of time, better communication, and more commitment to the actual sailing team. This means that meetings are organised and coordinated, in conjunction with the yacht designers by the syndicate design team coordinator if possible. These meetings include a broader group, including the assigned designer from your manufacturer of spar, sails, mechanical and structural systems. Perhaps most importantly, these meetings include the team’s key sailors. 3. Integration of sailors and designers Sailors are vital to the design team paradigm and ensure that the designers need to be part of the sailing team as much as possible. This has been one of the guiding themes at Team New Zealand since it’s inception, and has been adopted in various degrees by other teams, such as Mari Cha IV. The prerequisite is a sailing team that includes experienced veterans with views on performance and speed factors, and who know what they want to achieve. This includes sailors who can identify areas in which to “push the envelope”, and areas in which to stick with the basics. For a VOR team, this could be the skipper, key helmsman and trimmer(s). They are involved as early as possible and are included in general design team meetings. 4. Determine the key factors. An integrated team produces an integrated strategy. The team determines the key factors related specifically to the rule, the conditions, and the competition. The team then uses the best available analytical tools and data available to determine how the Volvo Race and Rule are different from previous events. They determine what elements of the big picture are perhaps more important to consider than others. Some of the key factors that have emerged from the design and research work carried since June are listed in Table 2 below. Table 2. Example of a few of the key factors for new VOR70 Rule/Race Factor Comments Powerful but flat righting moment curve with canted keel. A monohull with a stability curve like a trapeze dinghy (or a flying multihull!) will require a modified approach to trimming, crew attentiveness, and “forgiveness.” Limited sail inventory How will limited sail inventory affect our strategy, routing/performance, our operation Very high speeds are achievable Affects operations, handling & safety… speed and force of spray and shipped-green water will be higher than ever, with apparent wind speeds of 35+ knots in many conditions. What is the design answer for this? Is one needed? What is the operational approach? Conflicting demand of theoretical fastest shape vs. practical ocean “race-ability” Theoretically faster boats are narrow, and more forgiving boats are wider with a range of flare options. Where is the right mix? What tools are available to determine this? Where will the other competitors be? Where do we position ourselves? Offshore and Inshore Point System Accurate performance prediction, race modeling and game theory will yield a better understanding of the difficult decisions of offshore vs. inshore race boat. Aerodynamic models are rudimentary compared to hydrodynamic modeling Beam and/or stability issues are frequently miscalculated in even the most sophisticated design studies. Reason is yacht aerodynamics and sail models are not adequately developed. To create a competitive advantage with these key factors requires advanced tools, data and experience. 5. Advanced tools and data. Although a design office will provide the benefits of the tools, data, and experience of that particular office, alternately a design team approach often provides an opportunity to bring together a much wider variety of tools, data and experience specific to the VOR design and race key factors. In our case, here are a few examples: (a.) Tank and Wind Tunnel Testing Working with design teams over the last 20 years has provided me with the opportunity to test over a hundred tank models. The majority of these sessions have been large-scale models with Andy Claughton and the Wolfson Unit in Southampton, England. Merf Owen also has had the opportunity to carry out Open 60 tests with the Wolfson Unit. Both of us have carried out numerous winds tunnel tests in Southampton and New Zealand “Twisted Flow” tunnel as well. The experience from this kind of testing is crucial to a competitive campaign. Experience we have gained from our more recent tests is directly applicable to Volvo 70 design issues. (b.) Performance Prediction Tools As the author of WinDesign VPP which is sold and maintained by the Wolfson Unit and used by over 100 designers and naval architects around the world, it has been important to find ways to solve some of the most difficult problems in yacht performance prediction. The new generation of yachts with canting keels, multiple appendages, moving appendages, water-ballast, wing masts, and canting rigs have provided constant incentive to remain state-of-the-art. As a result our design team has the tools to be at the forefront of performance prediction, time-domain simulation of yacht physics, race modeling, and game theory. Manouverability of multiple appendage configurations, heel response of canting keel boats, seakeeping and surfing prediction are problems that first can be approached in an analytical way, prior to trying models, or ultimately full scale. (c.) Computational Fluid Dynamics Our team members regularly use and apply to yacht design/analysis the following tools: · Potential flow codes with and without free surface hydrodynamic analysis (See Figure 4 below) · Reynolds-Averaged Navier-Stokes codes (RANS) · 2D Potential/Viscous Codes Section Design Codes (e.g. Xfoil) · Vortex Lattice and other methods for aerodynamic analysis · Links to Sail Designer Codes for flow analysis, aero elastic membrane loading and response. Most of these tools provide some guidance, but most experienced teams would not be comfortable making important hull sizing or shaping decisions based on drag results from such tools. While often used to suggest “trends” of how a design parameter might affect drag, they are particularly instructive by providing off-body and on-body streamlines, pressure maps, and characterisation of the flow. There is still a lot of work to do to achieve generally reliable drag prediction with panel codes, and even RANS codes at the level of accuracy required for racing yachts, particularly high speed yachts with transom sterns like VOR70’s. The computational tools are important because they enable the modern design team to make informed decisions so when you are on the starting line of your first leg, there is no uncertainty or questions about why and how you and your team arrived at your “best” design. Only a few of the areas affecting the success and competitiveness of your VOR70 team are presented here. There are obviously quite a few more, but hopefully these points make a clear case that the modern design team approach would be very effective for any Volvo team. As it has been for most of the successful America’s Cup teams since that warm December morning in Fremantle seventeen years ago. *****

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