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Post Options Post Options   Quote Oli Quote  Post ReplyReply Direct Link To This Post Posted: 12 Nov 12 at 4:44pm
Originally posted by RS400atC

Originally posted by slop_idol

looking at the numbers id say that either the river/courses are very biased towards symmetric classes, and/or that the better sailors are in the symmetric classes.


Looks like the RS700 figures would challenge one of those possibilities?

It seems to me the current adjustment scheme really does not work in the real world where ability varies from class to class.
 
there is always one that breaks the rule Wink, but compared to how much the symmetrics move (60ish points) its only half the adjustment.
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Post Options Post Options   Quote RS400atC Quote  Post ReplyReply Direct Link To This Post Posted: 12 Nov 12 at 5:39pm
Originally posted by slop_idol

Originally posted by RS400atC

Originally posted by slop_idol

looking at the numbers id say that either the river/courses are very biased towards symmetric classes, and/or that the better sailors are in the symmetric classes.


Looks like the RS700 figures would challenge one of those possibilities?

It seems to me the current adjustment scheme really does not work in the real world where ability varies from class to class.
 
there is always one that breaks the rule Wink, but compared to how much the symmetrics move (60ish points) its only half the adjustment.

But with a high confidence level a 30 point shift ridicules the idea that the courses are somehow biased in favour of conventional spinnakers.
I am concerned that making such big changes as a result of the different abilities of the sailors will remove what credibility the PY system has.

How does that stretch of water differ from the national average in such a way as to make these changes justifiable? I can understand strong tides suiting faster boats, or waves suiting certain hull shapes, or high banks working aginst low rigs like mirrors. But a  tidal estuary where RS700's go well does not really suggest a strong bias favouring Scorpions etc. It seems much more credible that there is a strong Scorpion fleet sailing to a higher standard than the club average, and the RS700 sailor is also one of the better sailors.
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Post Options Post Options   Quote Peaky Quote  Post ReplyReply Direct Link To This Post Posted: 12 Nov 12 at 8:02pm
That's because the confidence thing is smoke and mirrors. If ten Lasers race one Solo you don't have any more knowledge about the Laser handicap than the Solo one, irrespective of any personal handicap issues that the Solo may have.

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Post Options Post Options   Quote craiggo Quote  Post ReplyReply Direct Link To This Post Posted: 12 Nov 12 at 8:27pm
Originally posted by RS400atC


and the RS700 sailor is also one of the better sailors.


Why thank you! (I'm one of the 700 sailors!!!

For interest, the club is situated on an extremely tidal estuary. Results are predominantly from two fleets with approx. 5-10 races a year where the fleet is totally mixed.

The Scorpion was sailed by an extremely good sailor and won most of the slow handicap series (He's now sailing a floating caravan though). I think the results tend to show that fast kite boats sail better than their PY while fast non kite boats struggle. What I think can also be seen is that boats that are fast upwind and tack quickly for their PY do well.

My point in sharing the data with you was to highlight the differences you will see locally with a broad range of skills, and to show why it is important for all clubs to use the scheme to enable us to get a good average.
Its also partly why I am a little sceptical in locally changing the numbers given the large changes needed.

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Post Options Post Options   Quote RS400atC Quote  Post ReplyReply Direct Link To This Post Posted: 12 Nov 12 at 8:49pm
I think what it may really show is that the PY concept breaks down in tidal conditions when the boats are too disparate.
For instance I won a race yesterday, I (RS400) was able to go fast enough to beat the current and get around the course, the other boats (PY1140 or so, keelboats) did not. A pleasant little farce in the sunshine, but not a workable PY race. Had I been racing with comparable boats, it would have been valid. Obviously that is taking things to extremes, but I believe that PY is trying to work across too wide a range of boats (to too serious a standard) and in denial of skill variation.
It's great for Scorpions vs Ents, or RS700's vs RS800's but mix that up and it starts to fall over.
The problem is we need to collect the Scorp vs Ent (etc) data and lose the distortions that come from comparing B14's with Miracles.
I'm all for racing all-in handicap now and then, but we need careful comparisons of like boats and similar sailors to generate the handicaps.
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Post Options Post Options   Quote craiggo Quote  Post ReplyReply Direct Link To This Post Posted: 12 Nov 12 at 9:59pm
RS400atC, you miss understand my comments.

With the exception of 5-10 races per annum the remainder of these results are comparing the boats within the slow handicap fleet >1015 or the fast handicap fleet <1015. So it is comparing Scorps against Ents etc. and not against the 700s etc.

There are certain classes in both of our fleets that seem to perform and there are those that do not. We have a real end to end skill range, and unfortunately we that range does not exist in any single class, instead certain classes have the bulk of the experienced sailors, while others are entirely made up of novices and for me this is what is really captured.
My own personal view is that these trends when used as part of the statistical averaging by the RYA to generate new numbers are fine, but to adjust locally to suit serve no purpose other than providing a personal handicap based on skill, so the best sailors get penalised. This is off course a local issue where no class exists which contains a broad skill range. At inland clubs with 25 RS200s of various skills this effect will not be visible.

At the end of day I do understand that the local adjustments will lead to closer racing locally, and in the absence of a decent measurement system we have little choice.
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Post Options Post Options   Quote Peaky Quote  Post ReplyReply Direct Link To This Post Posted: 13 Nov 12 at 10:09am
Originally posted by Peaky

Not for the first time in my life, I am a little confused.

To keep things simple, consider a two boat race. These boats, A and B, race each other 1000 times. Although different classes, A and B were initially given the same PY. 1000 races later (high confidence index) it is clear that A is faster, even when the helms swapped (so not a crew skill factor thing). In this latest version of the PYS, how do you know whether A should have its PY dropped, or B's increased? Perhaps a bit of both?

How do you ensure that you don't get the situation whereby Club X drops A's PY and Club Y raises B's?


Anyone? Is there a standard boat that is benchmarked off?
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Post Options Post Options   Quote RS400atC Quote  Post ReplyReply Direct Link To This Post Posted: 13 Nov 12 at 11:01am
Originally posted by Peaky




Anyone? Is there a standard boat that is benchmarked off?[/QUOTE]

Apparently not.
I don't think the RYA handle the data properly regarding returns from clubs where most of the handicaps are changed either.
For instance HISC change the numbers, every boat in the fast py races are running on lower py's.
The slow fleet may have increased PY's but 99% of the time they are not in the same race.
So if they get some data that says B14 should be 750, they need to rebase that because the B14 is racing against a Flying Dutchman at 810 or something.

So the info they have is B14 should be 750/810 of the FD PY

The data is being mangled by both clubs and RYA.

Since clubs like HISC do the same thing to their numbers every year, the effect is that boats like the RS400 keep dropping by the same amount every year. But, the Merlin is dropping faster.
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Post Options Post Options   Quote Peaky Quote  Post ReplyReply Direct Link To This Post Posted: 13 Nov 12 at 11:18am
Exactly. The PYS only rates boats relative to each other, not in absolute terms.

There is a risk that some clubs will pick and mix from other clubs suggested PY's - especially those that have been designated as having a high Confidence Index. For example, take Thornbury's Topper PY, Yorkshire Dale's Vortex PY and Hayling's 400 PY, because the clubs have a lot of 'confidence' in those numbers. But that would be mathematical nonsense.
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Post Options Post Options   Quote moomin Quote  Post ReplyReply Direct Link To This Post Posted: 14 Nov 12 at 9:53am
Can anyone answer this question that is confusing me at the moment.  I thought the new PY system was supposed to ensure the PYs were based on a good sample spread across a fleet i.e. the confidence factor, and avoid personal handicapping.  What I'm reading now is that if I am the only person sailing a particular class then to start off with the CF will be low (due to low number of appearances) but as more races are sailed will the CF rise or does the system recongise that it is a single boat and prevent personal handicaps? 
If the CF based on the stability of the PY then surely a single boat will actually create a higher CF faster than a small group, as the boat will be sailed to a more consistent way. Hence the high CF relating to the Scorpion in previous posts which seem to have been generated by a single good sailor.
Before you start I know PY sailing is not perfect and if I don't like it  then buy a different boat and go fleet racing etc etc.  I enjoy sailing my choices of boats and won't be deterred from sailing based on a PY, more of a stats/data geek interest!
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