After many years of work we were able, late in 2006, to complete the development of a new Velocity program (VPP) for the calculation of the speed of all sorts of ships and yachts under sail. This new VPP has features not included in other VPP's such as the possibility to calculate the equilibrium rudder angle to check the steering balance, the inclusion of a host of different keel and rudder configurations with or without bulbs, winglets, trim tabs, dagger-boards, lee-boards, etc, and a new mathematical description of the aerodynamic performance of different types of sails and sail combinations.
A lot of the development work in bringing about this new VPP went into the mathematical modelling of the performance of traditional sailing vessels such as can be found in Dutch waters. Often referred to as sailing barges, they feature gaff rigs and lee-boards. The mathematical modelling of the hydrodynamic side force and resistance of these traditional vessels was fine-tuned using the results of tank tests carried out at the Delft University towing tank some years ago, with a systematic series of Lemsteraken. The work for traditional sailing vessels is not yet finished. The present mathematical model is yet to be used to identify improvements in the design of these vessels.
Part of this work was sponsored by Hoek Design Naval Architect and they now have a version of this VPP to assist them in their own design work.