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A right to protest (PY Content avoid if bored)
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sargesail View Drop Down
Really should get out more
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Posts: 1459 		Post Options Post Options   Quote sargesail Quote  Post ReplyReply Direct Link To This Post Topic: A right to protest (PY Content avoid if bored)
    Posted: 16 Apr 15 at 10:39pm
Originally posted by chrisg

Originally posted by turnturtle

http://www.rya.org.uk/racing/Pages/NHC.aspx

So this is a formula based system based on boat variable right Chris, not based on CSF?  So theoretical exactly what Grumpf is after?
 
Interesting to see what differences it makes to individual race results.... are you publicly publishing them?

NHC for cruisers uses a base number that is calculated using a formula yes. Because there are so many variables in one "class" of cruiser from rig to keel configuration to engine inboard/outboard, feathering non feathering prop it was getting to a point where the RYA couldn't publish any reliable numbers for cruiser classes. So there is a simple formula to get a base number.

For our personal handicap series that base number is the national PY number. BUT, this base number then gets adjusted on a race by race basis using the same formula as the NHC system. This is a personal handicap so the whole point is each boat gets a different number not each class. This number takes into account CSF as well as anything else that might affect it such as older boats in a class perhaps.

Yes its available for all to see on the menagerie results page of the website. I don't think it's making "that" much difference to series results yet but will be interesting to see as the season progresses. Currently lasers range from approx 1054 to 1120 so it is making some adjustments!

And that Laser range sounds about what I would expect.  In fact it would be interesting to compare that spread with the times in a few club's Laser fleets, it the data were available.
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Chris 249 View Drop Down
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Posts: 2041 		Post Options Post Options   Quote Chris 249 Quote  Post ReplyReply Direct Link To This Post Posted: 17 Apr 15 at 12:31am
The list of base numbers looks awfully like the Irish ECHO numbers used to when they were pretty obviously base off IRC, or at least a simplified form of IRC.  In many instances they are too close to IRC for its to be a coincidence IMHO.
 
The base list also shows the weaknesses of a formula system.  Take the International dayboats - the Flying 15 is listed at an extremely slow .804 (slower than a Hunter 19!), the Etchells a bizarrely low .879, the J/24 comes in at .905 and the Dragon may as well not bother to start at .910.
 
In the systems that use the enormous database of performance that has grown up over decades for these classes, the Flying 15 is normally rated at a very similar performance to a Dragon, with the J/24 about 2+% quicker and the Etchells another couple of percent quicker again.
 
The Dragon is 50 years older than the Etchells, heavier than the Etchells, shorter than the Etchells, has more wetted surface than the Etchells, carries less sail than the Etchells, and has been proven to be slower than the Etchells for 50 years.  The fact that it is rated as a faster boat under this system just indicates how hard it is to arrive at a proper measurement rule for monos, and dinghies would be even harder to rate because they have more variation in planing characteristics, righting moment and other features.
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