Tuesday, 19 June 2018 - About Llsc | Rss

Sailing Committee implements RYA recommended PN changes for the Autumn series

Race data from our various handicap series has been input to the RYA website and their systems have analysed the data and produced suggested PNs for classes at L&LSC

UK Dinghy Handicap Racing – The Portsmouth Yardstick Scheme. The Adjusted PN numbers for L&LSC which will be used form Autumn 2012 are at the end of this articleDecades ago, the RYA adopted a scheme to allow boats of different classes to race ‘on handicap’ against each other and that scheme is still used today. It’s based on Portsmouth Numbers (PNs) where every boat is assigned a PN based on its comparative performance. So if a boat with a PN of 1000 takes 1000seconds to complete a course, then a boat with a PN of 1200 should take 1200 seconds.

The RYA publishes updated PNs annually through the Portsmouth Yardstick Scheme together with a method for amending handicaps to suit the conditions and type of racing of a particular club. Clubs have always been encouraged to return these amended handicaps to the RYA who consolidate them into the update for the following year. However these returns have always been sparse and 75% made no changes despite knowing that changes were needed.

Everyone knows that Handicap racing is never fair in the same way as class racing can be, but the RYA and the club are striving to achieve the fairest system practicable. Some boats will always perform well in certain conditions, some in others. However, in an ideal situation, in a series sailed over the full range of conditions, no boat or type of boat should have an advantage. So it should be possible for reasonably talented sailors in any class have a reasonable chance of winning over a series.

Recently the RYA has provided an on line system through which clubs can return their actual race data for the RYA to include directly in their analysis and Leigh & Lowton SC participates in this.

There are several reasons why using the ‘standard’ RYA PN handicaps is unsatisfactory. The RYA recommends the use of ‘club specific’ PNs – because:

1 The RYA PYN handicaps are an average of all returns from all venue types including rivers, gravel pits, small lakes, sea, tidal estuaries and large lakes. The ‘average’ of all these cannot properly reflect the situation at the Flash.

2 It is often the case that some boats benefit from the space available i.e. the slower more tactical boats can gain an advantage because of their manoeuvrability while the faster boats are at a disadvantaged as they don’t have enough room to stretch their legs.
So, the ‘standard’ PNs do not reflect the true performance of many of the boats sailed on our water.

3 It’s long been recognised that for some Development classes there is a massive lag between any increase in performance and the necessary change in RYA PN – potentially giving them an unfair advantage New classes or even those given a ‘makeover’ by a new manufacturer sometimes have a generous handicap either from their manufacturer or inherited. It’s rare they push for a change as it’s usually in their interest to get the class noticed through good results.

The New RYA recommended Handicapping Method at L&LSC

Race data from our various handicap series has been input to the RYA website and their systems have analysed the data and produced suggested PNs for classes at L&LSC. Basically, the RYA compute the average corrected time for a race and then for each class within it. This shows what change in each class handicap would be needed for their average corrected times to all be the same. Poor performers (outside 20%) are automatically excluded before class handicaps are computed by the RYA. That is intended to prevent undue influence from those who were late to the start, having a really bad day or simply new to the sport or the boat. Movements in class PNs are weighted so that a small the number of results for any class do not have an undue influence compared to those with large numbers of results.

After inputting all the data available, for all the series’ back to 2007, the RYA has produced a list of Leigh & Lowton specific Portsmouth Numbers – for all those classes with sufficient data available.

They have also give a confidence level. ‘Confidence’ refers to the stability of the number – not its accuracy. Confidence in the stability of PNs obviously rises as more race data is input and as we are in the first year of this process we decided to recognise the likelihood of increasing confidence, and so the Sailing Committee has agreed that the changes recommended by the RYA for L&LSC will be ‘damped’ by applying a % adjustment. Depending on the confidence level the % of any change applied will be as follows
0.0 = 0 % 0.1 = 33.33% 0.2 = 66.67% 0.4 + = 100%

The Adjusted PN numbers for L&LSC which will be used form Autumn 2012 are at the end of this article

Classes not shown did not return enough data at L&LSC to provide an accurate ‘club’ number. They will largely remain on the RYA ‘standard’ number. The Sailing Committee reserve the right to adjust PNs in the interest of fair racing – for instance in the event of a boat new to the club with known performance characteristics that affect likely PN at L&L. Where possible, this will be done using reliable sources of data-led information.

RYA club specific PN list for Leigh & Lowton SC

Data from 2007 to 2011 (completed 2012 series have also been inputted) with resulting RYA recommended PNs.

Numbers might slightly change when implemented in Autumn once Wed B & Late Summer Series have been inputted


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