S/Y BrunelSunergy

Early in 1996 we were approached by Mr. Benno Wiersma of the Senergy Company about designing a Whitbread 60 yacht for the Whitbread Around the World Race in 1997-1998.

He asked us to work together with the Judel-Vrolijk design office in Germany. Rolf Vrolijk and Peter van Oossanen defined a work programme for this project in April 1996. We were responsible for the study of important hull form variables through use of our VPP and all of the research and development work that had to be carried out.

The first part of the VPP study was completed in July 1996. Rolf subsequently prepared the first linesplans based on the outcome of this study. Three 1/8th scale models were then tested in August and September 1996, in the Southampton Institute towing tank by the Wolfson Unit. We co-ordinated this test programme and assisted in the analyses and interpretation of the results. The impact on performance of different various water ballast configurations were studied in the towing tank.

The tank test results were used to fine-tune the VPP and a special version of our VPP was prepared for Whitbread 60 type boats. The second part of the VPP study was then completed, including the race analyses work, comprising race simulations for each of the VPP designs, for a number of different weather scenarios as provided by the Netherlands Meteorology Institute (KNMI). We were able to define the optimum beam on the waterline of the hull, alongside a number of other important design parameters. The design of the hull was completed by Rolf after these tests and SP were given a contract to do the structural design.

The study of different keel geometries was also carried out by our office. We performed a series of Computational Fluid Dynamic (CFD) studies utilizing our Doublet-Source Aerodynamics code. Both ?L? and ?T? type keels were investigated. We also carried out viscous flow analyses calculations using our boundary layer code. This work was completed in December 1996, on the basis of which an L-type keel was designed and built. The yacht was launched in April 1997.

In May and June 1997 sufficient funds had been found to test the existing keel and 4 variants thereof in the low-speed wind tunnel of the German-Netherlands Wind Tunnel organization in the Netherlands on half scale. During this series of tests we found that a specific T-type of keel had a better performance than the keel that had been designed and built. Unfortunately, insufficient funds were available to then build and fit this keel to the yacht, as had been intended. The crew had elected to use reserved funds for this purpose for buying additional sails. Our analyses of the final race results showed that the boat would have performed markedly better had this keel been fitted.

Finally, we prepared the initial target polars for the boat and sail selection charts, based on our specially-tuned VPP. These polars and charts were fine-tuned during sail testing sessions on the North Sea (the boat was based in IJmuiden), in the summer of 1997, before the start of the race.

After the race was over, we received the structural analyses report on Brunel Sunergy that had been prepared by the Wolfson Unit. The Wolfson Unit had been contracted by the Race organizers to check that the participating boats had been built according to the requirements of the ABS Rules. This report showed that the structural weight of Brunel Sunergy was about 500 kg heavier than the other boats participating in the race (all of which had been designed by Bruce Farr and his team). This meant that the boat had significantly less stability than the competitors. This, combined with the fact that the boat had not been optimized for the Code Zero (mast-head) genoa that appeared for the first time during the race, meant that the boat was less competitive in strong wind conditions. Nevertheless, the boat was able to win one leg and come second on another leg of the race. It is still unclear whether the 500 kg of extra structural weight of the yacht was due to a less-optimum structural design by SP (SP only engineered Brunel Sunergy for the 1997-1998 Race), or whether the builder of the boat (Holland Composites in Lelystad) was too extravagant with resin, micro balloons, etc.

During the Sydney stop-over, Peter van Oossanen assisted in the re-fairing of the keel and rudder, after the fitting of templates had shown that the finish of both keel and rudder were not up to the required standard.

  • BrunelSunergy
  • 18.2 m
  • Holland Composites
  • Design together with Judel/Vrolijk, R&D, testing and analysis