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My research is focused on the automation of the design process for sailing yachts. When the optimization can be done on the computer, optimal designs become available to every cruising sailor and not only to race-syndicates with million dollar budgets.

A numerical method that is successfully applied in yacht design are the genetic algorithms. The computer is used to improve a design in an evolutionary process through many generations. I presented first results of this method at the Second High Performance Yacht Design Conference 2006 in Auckland. The validity of the optimum depends heavily on the accuracy of the predicted speed potential of the yacht. The speed must be calculated from the geometries of hull and sails, where the resistance of the hull can be predicted on the basis of the research at the TU Delft. All influences on driving- and resistance-forces are still not known though. Of great help were the towing tank test data of a Dehler 33. They were thankfully supplied by the SVA Potsdam. The status of my work as of 2012 is described here.

Since the beginning of 2013 all test results from the towing tank of  the TU Delft are available on their web-site. This is a new invaluable knowledge base. Based on this experimental data and an additional boundary-layer calculation, I have developed a new correlation for the residual resistance. A prerequisite for this task is explained here, the theoretical background and the results of the regression analysis can be found in this report. The database was increased by adding the towing tank results for the Delft-372 model. UliTank is a computer program that incorporates all the newest findings. In 2015 the Sailing Yacht Research Foundation published on their website towing tank results that were conducted in 2003. I used these results to increase the database of the regression analysis for the new version UliTank_3.3.This new version computes the resistance with appandages in the heeled attitude and with leeway. UliTank_3.3 can be downloaded  here.

The next step is the modelling of the sail forces. These are based on the aerodynamic characteristics of the 2D sail sections. A first step is the program Sail2D.

One of the tasks in optimization is the creation of a lines plan for the hull, based on the optimization parameters. The program UliLines was written for this purpose and can be downloaded at UliLines.

In April 2011 the Yacht Research Unit Kiel allowed me to use their circulating water channel for the determination of the different resistance parts of hull and appendages. Unfortunately it turned out, that a CWC cannot compete with a traditional towing tank, the accuracy and repeatability of the results is not sufficient (report in German).

To define the constraints for the optimization it became necessary, to estimate the weight of the yacht for a given design. The structural weight can be calculated from the scantling rules of the classification society, but there is a gap if it comes to the design load for the keel-hull junction. To get reliable data for this design task, drop tests with a model-yacht were conducted in the summer of 2009. The results are available as pdf-file. These results show, that for yachts with a low ballast ratio conventional scantlings might result in a structural design that is too week.

E-mails will reach me at "ulrich[a]"
September 2022
Preparation of drop tests at lake constance

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