VPP4 is a conventional VPP for Cruiser/Racer yachts. It is based on a hydrodynamic model using Keuning’s regression of the Delft Systematical Yacht Hull Series, and an aerodynamic model based on wind tunnel tests from the University of Applied Sciences Kiel Yacht Research Unit. Results similar to the ORC Designers VPP can be generated, albeit with a lesser degree of detail. The advantage of VPP4 over the ORC designer VPP is, that it does not need any existing line drawings of the hull. The Keuning regression method allows to predict the hydrodynamic forces and moments only from principal dimension of the hull. It is thus capable to optimize principal dimensions of a yacht in short time in the priliminary design phase.
Main dimensions of hull, rig and sails are provided using human-readable commented JSON files. Here is an example of a commented JSON file, defining the yacht’s rig dimensions (The Visual Studio Code editor is an excellent choice to edit the JSON text files).
JSONs for various sail set types exist: Mast Head, 15/16 fractional rig, 7/8 fractional rig, 100% jib and 130% jib and conventional mainsail and squarehead main sail. Example files for some hulls and rig types are provided.
VPP4 features a user interface, allowing to load a larger set of JSON files for the hull, the rig and sail set configurations. These can then be set for a particular combination of hull, rig and sail coefficients.
The use of VPP4 is quite straight forward, please try to figure out. A short manual is in preparation, please remain patient. The published version of VPP4 uses local optimization of the sail trim (depowering). The results may depend on a proper choice of initial values (guesses) for boat speed, heel angle and so on.
You may download an installation package for VPP4 right here.