Yacht Research Unit Kiel

Computational Fluid Mechanics and Experimental Flow Investigation for Yacht Designers, Sailmakers and Sail Sport Campaigns

Yacht Research Unit Kiel is a commercial spin-off of the Univ. Appl. Sciences Kiel providing flow investigation and optimization services for the sail sports community.
YRU-Kiel carries out CFD-based aero- and hydrodynamic analysis with subsequent form optimization. In addition YRU-Kiel operates a Twisted-Flow-Windtunnel to be used within the sail design process of sailmakers as well as yacht designers, and a hot water open water circulation tank for cost efficient tank testing of small models.

In a recent study YRU-Kiel carried out full scale flying shape measurements of a symmetric spinnaker on a 38' sailing yacht. The measurement techniques is based on photogrammetry: simulaneous images are taken with digital cameras from different views. Special markers (so called coded targets) fixed to the spinnaker are identified on any image by a pattern recognition algorithms. From the 2D-coordinates on three to four images the 3D-location of the coded targets in space are calculated by a special software implementing the photogrammetry algorithm. This technique is used in our wind tunnel on a regular basis, however using this method in full scale was new. For the full scale measurements images are taken from 4 tenders sailing around the yacht at predefined locations.

The motivation behind the study was twofold: firstly we wanted to compare the flying shape as acquired on the water with the one obtained in the wind tunnel. The main motivation however was to get some data for validation of a fluid structure interaction simulation code, which is able to calculate the flow around a spinnaker in full scale and take into account the structural behavior of the spinnaker with the real fabric properties.

While the photogrammetric method was easy to adapt to the full scale measurements by recalibrating the cameras to the dimensions of the sailing yacht rig, the real challenge of this investigation was to cope with the instationary of any measurements in natural environment.

The study has been carried out by Julien Deparday of ENSIETA/Brest, FR and Johannes Mausolf of FH Kiel. Special thanks to Thomas and Manfred from the local sail club PTSK for their tireless help and support, to the Kieler Yacht Club for providing two RIBs and to all the students forming the team. Kiel 21.6.2010, Gr