Finally - the Bruce Farr design Open 60

The Daily Sail catches up with Jean-Pierre Dick and the radical new Virbac

In early 2002 Farr Yacht Design was commissioned by a French client to develop an Open 60 design targeted at winning the 2004-2005 Vendee Globe, widely regarded as the most intensive and extreme single-handed around the world race. The Open 60 class, as its name implies, is a development class that has spawned a wide array of new technological developments in yacht design including the use of wing mast spars, PBO & aramid rigging, canting keels and water ballast. Farr Yacht design is thrilled to be able to apply our design philosophy and depth of experience to the development of an innovative Open 60 design.

The principal design brief for this project was to develop a state-of-the-art Open 60 specifically designed for winning the 2004-2005 Vendee Globe Race. Beyond that, our desire was to develop a safe, easy handling design capable of achieving a high percentage of its theoretical performance potential while being sailed single-handed.

Having not designed a modern Open 60 we were starting with a blank sheet of paper in terms of our understanding of the rule space. After a series of debriefing sessions with the client to understand their desires and learn from their experiences with current generation Open 60’s we undertook a series of conceptual sessions where the entire team at FYD identified particular areas of the design where we felt significant design/construction/system or operability gains could be made.

Research Program

Parallel to the development of these conceptual ideas we embarked on a significant research program to allow us to analyze designs and predict their relative performance. Modeled after our successful Volvo Ocean 60 research efforts our research explored seven areas:

- Velocity Prediction Program Enhancement & Validation
An accurate means of assessing the performance potential of a candidate design is a fundamental piece of our design process. Our proprietary VPP has been in continual development over the past 10 years, and has a number of capabilities specifically tailored for use on ocean racing yachts. For the design of an Open 60 we made extensive modifications to the hydrodynamic and aerodynamics models in the VPP to cater for the unique aspects of these designs. These new formulations have been verified with publicly available data sources and the final performance numbers agree well with full scale Open 60 performance numbers.

- Weather Model & Analysis
Critical to optimizing an around the world race boat is developing an accurate performance profile of the boat around the course. Ten years of global weather data files were obtained from Chris Bedford of Sailing Weather Services covering the typical Vendee Globe race period. Fleets of designs were then analyzed using custom router software for 30 start dates in each of the 10 years. The results were then processed to develop an average mileage table distribution. Combining the mileage table with VPP performance information allows both the computation of the elapsed time over the course and a means of identifying sail set and flotation cross-over information critical to the design of sail plan and yacht systems.

- Sizing Series Exploration
A series of 9 base Open 60 designs exploring variations in beam and displacement were developed and evaluated using the VPP and weather model. These designs produced a systematic series from which the effects of various design parameters on elapsed time could be compared. Analysis of these results over various course weightings lead to the selection of a target set of hull parameters.

- Appendage Configurations
One of the design areas with the most freedom is in appendages and we have spent significant time evaluating the merits of different appendage configurations. The interaction effects of dagger boards, canting keels and off-center rudders and their impact on the boats performance can be dramatic. To understand these effects we have developed detailed computational models and integrated them within the VPP framework to capture performance effects. The fin design and canting mechanisms have been designed to exceed the rule structural requirements while being optimized for weight and stiffness. At Farr Yacht Design we continuously improve the foil designs incorporated into the appendages. This design contains our latest foil and bulb designs produced in-house using advanced CFD tools many of which are descendant directly from our involvement with America’s Cup design programs.

- Balance and Handling
One of the critical design goals was to achieve an easy-handling, responsive design. This is intrinsically related to the appendage and sail plan positions and loadings at various points of sail. A detailed review of existing Open 60’s and Volvo 60’s combined with an exploration of the hydrodynamic loading changes with various appendage concepts was undertaken prior to locating the rig, refining the rig proportions and positioning the appendage elements. It is our belief that significant performance benefits can be achieved with a well-balanced design and our appendage and rig layouts reflect this.
§ Ballasting Options
The Open 60 rule allows significant latitude in the use of additional ballasting capability whether through canting keels, water ballast or a combination of both. FYD has extensive experience with the use of water-ballast on boats such as the VO60’s and we have capitalized on this to develop a unique ballasting system for this design which we feel will produce a significant increase in performance over the current generation of designs.
§ Sail-Plan Sizing & Sail Selection
Significant design effort was placed in developing the rig sizing and proportions. Utilizing the performance predictions and weather models we were able to develop a sail plan concept that we feel is well suited to the Vendee Globe race but can be easily added to for other not-so-reaching oriented courses or short-course racing. By tailoring the rig concept to the expected weather profile of the race it is possible to target the sail sizes to produce a more even usage profile for each sail which is important to extend the longevity of the entire sail set. Part of this rig development package included the development of predicted sail set crossover angles and windspeeds that reflect the ballasting and performance capabilities of this design. This information was then conveyed directly with sail designers to assist in the construction specifications of the sails.

Design Development & Construction Support
FYD prides itself on our ability to provide the complete design package from research and conceptual development through to detail design including all of the primary structural elements. By achieving complete integration of structural design requirements with performance and operability requirements we are better able to develop optimized solutions. In few designs is this more critical than on an Open 60 where weight savings will result in significantly improved performance.

Detailed 3-D modeling of internal layouts, decks and cockpit arrangements allowed us to more efficiently communicate concepts to the client and builder resulting in a more accurate weight tracking and the avoidance of interference problems that can plague designs with complex space claims such as this. The detailed geometric representation of the design allows for very detailed assessment of rule compliance, specifically with regard to the amount of residual buoyancy in the structure and the levels of damaged water planes. The net result of this is a lighter, more highly optimized design that meets all of the IMOCA rule requirements. Optimization of ballast tank systems and volumes was all completed in 3D to achieve the maximum benefit from water ballast additions. This further let the ballast system be integrated into the structural design to produce a well-integrated product.

The sailplan is quite a departure from other current generation Open 60’s and reflects detailed optimization studies using the course and weather models. The selection of a conventional carbon rig with PBO rigging was the result of internal research studies that traded the weight, VCG and windage penalties of rotating wing mast spars and conventional spars. Further we feel it may be easier to achieve full performance potential from the sail plan using a conventional spar.

Reproducing the design appendage shape is critical to the performance of the boat so the keel fin, bulb, rudder and dagger-board surfaces were developed as Pro/Engineer 3D models, which are then supplied directly to the builder.

Operational Aspects
It is critical that the onboard systems allow the solo sailor to realize a large percentage of the achievable performance of the yacht in any condition. To this end we have worked extensively with the client and builders to properly integrate the yacht’s system into the design.

The deck-layout has been optimized around the requirements of single-handed sailing and has been augmented with an additional driven utility winch to ease handling of many lines, including all mainsail reefing controls which can now be manipulated from the cockpit. This minimizes the amount of time required on deck and thus improves safety. The cabin shape has been adjusted to maximize its effect on the limit of positive stability but shortened to allow a flatter deck area around the mast for reefing to minimize the danger of standing by the mast. Significant effort has been paid to the requirements of maintaining optimal visibility for the sailor when on deck.

Safety concerns are paramount in the design of a solo Open 60 and as such we have placed emphasis on access ways throughout the boat. As the Vendee is a no-outside assistance race significant importance has been placed on survivability in the event of collision. This is reflected in the hull structural layout and in the design of the appendages. The boat is fitted with two asymmetrical dagger-boards that can be inverted and used on the opposite side in the event of damage to one board. Structural support for the dagger-boards has been developed to avoid damage to the hull in the event of an impact. The keel canting mechanisms have been integrated into the design to produce a low weight solution but maintain redundancy in the event of a ram failure. The rudder and steering system has been designed to allow kicking-up in the event of a collision and to allow the windward rudder to be removed from the water when not in use to improve performance. Significant effort has been placed on refining a steering system that minimizes the number of linkages and connections to maintain a high level of helm response while hand steering.