Multihull correction factor

The “Multihull Correction Factor” Most sailors are aware of “Yardsticks”. These are time correction factors that are applied to dinghies to enable mixed fleet race results to be meaningful. If all sailors sail the identical boat then producing results would be easy. But to compare different classes it is necessary to provide a “time correction factor” to apply to the elapsed times for each boat.In theory this Yardstick adjusts the corrected times of all classes so that if two equally competent (and very good) sailors were to compete in different classes over say 6 races then both should have won 3 times out of 6. The number of 6 races is not important but merely used for illustration purposes. The use of yardsticks aims to provide sensible results across classes in a common race at Clubor Regatta events. These yardstick values have been arrived at by studying the relative results for different classes over many races. In all cases the relativities are only considered for known very good sailors. As a consequence, if a race has a particularly good sailor then that sailor should head the results irrespective of what class of boat he sails. This equally applies to if there areseveral particularly good sailors in the race and the rest are good to average. The yardsticks are rarely questioned by sailors as they appear to provide reasonably sensible results in most races.? BUT when two very dissimilar classes are compared such as Monos and Cats or Monos and Sail Boards then the Yardsticks do not provide sensible results for many races. In an attempt to overcome this problemthe VYC “Multihull Correction Factor” was brought into being. Like the YS it is a measure of the relative performance of say Monos and Cats BUT this is done just on a race by race basis. This then takes into account the wind and sea conditions for a particular race and provides a further scale factor to apply to all the Cats in the combined fleet. The major problem here is that unlike the YS whichare based on the relative performance of the best sailors in a class the MCF can only compare the results of those sailors who sailed in the particular race under consideration. It is a virtually impossible task to compare the “competency” of sailors on such different classes. Even if you tried to set up races where they both sailed the same class to see how close in skill they were, that wouldnot work as the experienced Mono sailor would have an advantage in Monos and conversely. The YS system endeavour to establish relative comparisons to provide “fair racing” between classes. So must be the endeavour of the MCF. As the MCF is applied on a race by race basis then the question becomes what is needed to provide fair inter class racing for this particular race. I suggest the aim is that(as per using yardstick) there is a fair and equal chance that the first place will go to a Mono sailor or to a Cat sailor and likewise for the second and third places etc. That is, the results are not biassed to a particular class because of the prevailing wind and sea conditions. Now consider your local club. Presume that your club’s Mono fleet is a group of competent sailors and that on a race byrace basis one of number of sailors is likely to win or come second or third etc. That is, there is not one sailor who dominates and is likely to win most races. Presume likewise that this is equally true of your Cat fleet. So it is fair to say that the front (say) half of either fleet is quite competent. To generate the MCF for a race you take the average YS corrected time for say the first 6monos and divide this by the average YS corrected time for the first 6 Cats. I.e. MCF = Av (first 6) Monos / AV (First 6)Cats. You then multiply each cat’s YS Corrected time by this scale factor to arrive at their MCF corrected Page 1 of 5

time. Intuitively and by studying some results this provides fair comparisons for mixed fleet racing provided there is no standout sailors in either sub...