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Professor Linda Wolstenholme creates new, fairer sailing handicap formula

Wednesday, 19 August, 2009

A new formula for sailing handicaps has been created by Linda Wolstenholme, Professor of Applied Statistics at Cass, which uses simple boat measurements, rather than results of past performances, to generate a simple, fair and transparent system for sailing races.

The method aims to address the problem at the competitive club level of sailing whereby handicap numbers are decided in a subjective manner by club officers or are based on previous performances.

Boats at many cruiser racing events range in length and design. A handicap system takes account of these differences and allows the performance of the sailing crew to be measured, independent of the boat.  Sailing handicaps have a long history with most theories based on past performance, which are limited by the need to actually have some performances to draw from.

Worldwide, a variety of ad hoc past-performance measures and formula-based approaches have been used to determine yacht handicaps, but no unique and universally-adapted model has evolved.  A significant problem for those at club level trying to set handicaps is the degree of secrecy in the procedures adopted at international level, and also the complexity of the boat data required.

The new measure is based purely on the basic boat measurements that everyone has listed in their boat literature.  These include the water displacement caused by the boat, the length of the waterline, the area of the mainsail, the area of the largest foresail, the draft of the boat and the width of the beam.

The development of this formula showed that the draft of a boat, and hence the keel, was critical.  The keel has a strong influence on sailing performance because it acts in water as a sail does in air.  It also provides resistance to sideways movements in the water.  The formula relates to boats with a classic fin keel.  Some cruising yachts have relatively short twin keels, which has a significant effect on sailing performance, particularly in the ability to sail against the wind.  Professor Wolstenholme has developed a separate routine that takes account of multi-keels.

Professor Wolstenholme says: The benefit of my new formula is that not only is it easily understood by club members and sailors who are not necessarily statisticians, but it also fits in with the Portsmouth Number system favoured by the Royal Yachting Association.  Importantly, it provides a quick, transparent and impartial way to assign a handicap number.

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