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PY Numbers for 2017

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Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Topic: PY Numbers for 2017
    Posted: 10 Mar 17 at 11:54am
Originally posted by transient


Is Sailjuice et al forcing the move or is it a response to grass root needs.....not that it really matters I suppose.  


I think that's a very good point and the truth is we don't know, concentrating a group of results around a particular type of water that favours fast boats thereby forcing slower handicapping of those they would wish to swell their ranks to compete equally, does this influence the overall handicap, is it the reason the Laser for example is getting slower, dragged there by the 1115 they recommend?

They (the PYAG) say not so, or I seem to recall that denial a few PY threadyears ago, but I still have my suspicions.

Does it matter? Well along with the lack of transparency generally I think it does, don't we all look for a scapegoat or a 'conspiracy' or is that just me?
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Post Options Post Options   Quote Cirrus Quote  Post ReplyReply Direct Link To This Post Posted: 10 Mar 17 at 12:15pm
.. It is just you  .... as usual Wink

It is not 'Sailjuice' btw that you should refer to - they simply sponsor/promote a winter series .. it is the 'Great Lakes' handicap system thqt is used by the clubs and events involved (and many others outside this particular series as well). 

It works.  Well it works a lot better than the raw PN approach whether you are into the theory or not.  IF the idea behind handicapping is to reflect the relative speed capability of classes - and that is very obviously NOT the same as the average of all results for any class it simply does a better job.   The SJ series does attract a lot of good currently very competitive examples of many classes.  They all race on the same water on the same day.  It effectively provides a more relevent or structured sampling basis to consider.  The 'front' of each class tend to get nearer the true capability out of their respective classes.    The critical thing is you don't kid yourself and others that the mantra of  'more is better' all other things being equal when looking at the available sample as seemingly the crude or 'raw' PN system does...   
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Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 10 Mar 17 at 12:47pm
It certainly works for you, do the Sailjuice management like their new Halo's? ;-)

But seriously of course it works for them they have a tailor made system for generous flat benign water.

The point I'm asking is how badly does it skew the system for those of us with different conditions.
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Post Options Post Options   Quote jeffers Quote  Post ReplyReply Direct Link To This Post Posted: 10 Mar 17 at 12:56pm
Originally posted by iGRF

It certainly works for you, do the Sailjuice management like their new Halo's? ;-)

But seriously of course it works for them they have a tailor made system for generous flat benign water.

The point I'm asking is how badly does it skew the system for those of us with different conditions.

I dont believe it does aside from the raw data (elapsed times and class) going in to the PYS system.
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Post Options Post Options   Quote Cirrus Quote  Post ReplyReply Direct Link To This Post Posted: 10 Mar 17 at 4:39pm
The GL numbers are not just  used on 'flat' fresh water .... anymore than Portsmouth numbers are just useful for the salty stuff.  Many of us have raced under the GL numbers in coastal sailing weeks and other sea based events and it works fine. 

The difference is that classes at the SJ events are more frequently represented by more good boats and helms from a lot of active classes.  If you compare the performances of good boats/crews from each class racing on the same water and in the same conditons you are more likely to be able to differentiate 'class performance potential'.  The good boat /crews in each class get much closer to the top performance capability of each type of boat. The raw PN in effect just 'weighs' all inputs from all clubs.... (slow tired old clunkers .. and their boats etc Wink) it does not purport to produce boat 'performance potential' comparisons at all nor would it be easy to do so however large the sample.  In effect it is much blunter knife !  To be fair it is not really trying to either .... which is why the increase in major handicap events is putting so much pressure on this 1st generation approach.  It was not really intended to be used in real anger imo.  When developed it was more about the occasional club menagerie race .... 'a real local system for local people'.  

As for different conditons having an effect - well of course it does.  But that is another point.  If you sail in choppy lumpy stuff you need to be able to generate  plenty of  power (in 'Clarkson' sense of course) ideally coupled to longer waterline length all other things being equal.       

   


Edited by Cirrus - 10 Mar 17 at 4:42pm
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Post Options Post Options   Quote tink Quote  Post ReplyReply Direct Link To This Post Posted: 12 Mar 17 at 11:30am
Out of interest I sorted the list by number of returns, logical the more data the more it is going to iron out any anomalies. 

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Post Options Post Options   Quote Eisvogel Quote  Post ReplyReply Direct Link To This Post Posted: 13 Mar 17 at 9:47am
Originally posted by tink

Out of interest I sorted the list by number of returns, logical the more data the more it is going to iron out any anomalies. 

The basic assumption underlying that is that the data has a normal distribution, ie it follows a bell-curve. There are a few very good sailors, a few very bad ones, and the majority is in the middle. I don't know whether that assumption holds for normal club racing events. If you have skewed data, then having more skewed data will not improve it.

As Cirrus mentioned in a previous post, just taking data from events where the better sailors compete eliminates one big factor: variation of individuals' ability. If every sailor is at the top of their class, then you won't have too many extreme outliers. So that's one important variable eliminated. We still have plenty more, such as course suitability for the class, and weather, but these are different at every event, so we can't really account for them in a one size fits all yardstick value.

After following this thread over time I have come to the conclusion for myself that no handicap system does account for all the variables, certain courses and conditions will always favour some boats over others, so I agree with whoever said that you just sail your best and compare yourself to the people who usually come close to you... If, as it will undoubtedly be the case, some classes always seem to win, then lobby your local sailing committee to penalise them a bit. After all, it'll make racing more interesting for that class too, as they will have to work harder to keep winning ;)


Edited by Eisvogel - 13 Mar 17 at 9:49am
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Post Options Post Options   Quote jeffers Quote  Post ReplyReply Direct Link To This Post Posted: 13 Mar 17 at 10:32am
Having attended a few of the winter events, yes there are some top helms there but there are also a fair number of mere mortals there too.
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Post Options Post Options   Quote Cirrus Quote  Post ReplyReply Direct Link To This Post Posted: 13 Mar 17 at 11:43am
    Having attended a few of the winter events, yes there are some top helms there but there are also a fair number of mere mortals there too.

But you can now also bias or further select  the sample from these events  .... that is if you simply want a number more representative of potential boat capability.   Selecting the specific sample to crunch meaningful numbers for from the overall mass of boats is what it could be about.  The PN 'way' is much much simpler - and implicitly has to assume too many assumptions about distributions and relevance.   In short 'more' is not necessarily 'better' - sampling has to be more selective if you want to get closer to the potential of any boat - one way IS to look at events like the SJ ones and weight the sample towards the front.  Not the only way of course but it can get closer to reality.

Consider a class, any class you like, that has become very popular at club 'n' ... it grows and inevitably attracts a lot of the 'better' sailors amongst others from other classes at that club.   Other pre-existing classes now don't seem to 'win' as many events and the new class gets to partly dominate in the club results.  The handicap returns from this club (under the PN approach) seem to indicate that this new class is really quite fast ... and in aggregate it gets 'adjusted' to reflect the perceived speed and pace of the boat.   The pre-existing classes could, again in aggregate, get a bit of 'help' in the subsequent years handicap numbers.  Now the new boat is relatively penalised when in reality it is very likely to reflect the migration, disproportionately, of 'better' crews at maybe just a few clubs.  And this is just one possible outcome  !  

There are obviously other potential problems with just looking at a 'mass' of data in any statistical examination - using all the raw numbers available don't always help.  Sampling when at least some of the 'crew' effect can be reduced should be considered imo – more often.   The PN method and all other systems can never be perfect - however they can be improved.  The GL (alternative) approach partly goes down the path of relevant sampling - given their declared objectives it should not be a surprise to anyone.....



Edited by Cirrus - 13 Mar 17 at 11:45am
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 13 Mar 17 at 2:47pm
But you still need a number of helms racing a given class, the 32 races returned for the Dart 16 could have been a single keen helm or a dozen guys sailing two or three races a year. Neither will be a true representation of either the average performance of the boat or it's best potential (unless a single top helm choses to race the only active D16 in the country.
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