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Chesapeake Sailing Yacht Symposium 2009 — A Summary by Dudley Dix

[Ed: Noted designer Dudley Dix recently attended this symposium and kindly sent in a report. Although most of the papers at the Symposium dealt with issues affecting large monohulls, the following papers might be of general interest to our 'technical sailors', so Dudley's summary is included here.]

The symposium

The Chesapeake Sailing Yacht Symposium takes place at St John's College in Annapolis, every second year. It is sponsored by a group of sailing bodies that have a deep interest in technical research and development in all aspects of sailing boats and ships.

The sponsors are:

Summary of the 'generically-interesting' papers

Two researches (Keuning & Verwerft) from Delft University in Holland presented a paper titled "A new Method for the Prediction of the Side Force on Keel and Rudder of a Sailing yacht based on the results of the Delft Systematic Yacht Hull Series". This dealt with development of ways to more accurately calculate the independent effects of foils and hull in the overall evaluation of sailboats when heeled. With methods currently in use the accuracy falls off as heel angles increase. Included in their research was interaction between keel and rudder(s) and the yaw moments of hull and foils.

This was followed by a more technical paper by Fabio Fossati and Sara Muggiasca of Politecnico di Milano in Italy, titled "Sails Aerodynamic Behavior in Dynamic Conditions". They researched the behavior of sails and the flow patterns around sails with the rig moving to simulate pitching at sea. They did this work as a first step toward anticipated development of performance prediction programs at some time in the future. Performance prediction programs will predict dynamic speeds of boats with accelerations and decelerations due to wave action taken into account. In contrast, velocity prediction programs predict sailing speed in a stable condition on flat water.

Before lunch break on the Saturday there was an excellent guest presentation by Britton Ward from the Farr Yacht Design office. He showed us a presentation about high performance sailing, as it exists at present, covering all types of speed sailing in both monos and multi-hulls.

Next was a paper titled "Tacking in the Wind Tunnel", presented by a group of researchers from the Yacht Research Unit of the University of Auckland in New Zealand. The purpose of their research was to evaluate loss of speed when tacking and compare the results with the theoretical numbers obtained from Dynamic Velocity Prediction Programs (DVPPs). It also evaluated the results on the speed through the tack of different methods of tacking the headsail, i.e. freeing it early, keeping it trimmed as long as possible and backing it to push the boat through the tack.

Bill Beaver and John Zseleczky of the US Naval Academy Hydromechanics Lab presented "Full Scale Measurement on a Hydrofoil International Moth". They used the ship towing tank at the Lab to measure hydrodynamic resistance of a foiling Moth hull and three different foils, at various attitudes and speeds. They also used the towing tank to measure aerodynamic resistance of the hull with racks and helmsman upwind in flying mode.

The last paper was "Alpha and Rocker—Two Design Approaches that led to the Successful Challenge for the 2007 International C–Class Catamaran Championship", presented by Steve Killing of Steve Killing Yacht design in Canada. This covered the comparison of conventional and foiling catamaran designs tested in the run-up to the successful Canadian challenge for the C–Class cup. He presented their findings in the spirit of sharing information, which the author feels is important to the continued survival of the C–Class catamaran.

For those who wish to follow up on these or any other of their interesting papers, print or CD versions are available from the organizers at www.csysonline.com

As reported to www.smalltrimarandesign.com by Dudley Dix, April 15, 2009.    Website:  dixdesign.com


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