Farr Open 60

We've featured a lot of designer's work here at SA, but one that we've not (but always wanted to) is Bruce Farr. We've always admired his work, and though we have printed other's criticisms of Farr, we remain fans. When the forum talk recently centered on a new Farr Open 60, one of the few Farr's office has not done it was time to get in touch with Farr's office. Dave Millett, former PHRF weenie (ha!) and now Design Sales & Marketing Manager for Farr provided us with the following designer comments, pictures and movie.

While this in no way is anything other than what Farr has to say, it does provide some interesting insight and information about what promises to be a closely watched boat. Thanks to Dave and the Farr office, and we look forward to bringing more of their work for you to see. - Ed

In early 2002 Farr Yacht Design was commissioned by Jean Pierre Dick 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. 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.

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:

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 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.

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.

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. 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.

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 sail plan 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.

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.

Principal Characteristics Design 498 – Open 60

04/15/2003