IC (DC) Yardstick

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Christian AUS
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IC (DC) Yardstick

Post by Christian AUS » Sat Jan 12, 2008 11:01 pm

Okay I have worked out a Yardstick for the DC's based on the results of the Invitation Race and the 6 heats sailed at the Worlds. I have used the top 6 IC's vs the top 6 DC's (I know this can create areas of error but the top 6 in both fleets were the most consistent results statistically over racing) and then used the current and pretty accurate Australian IC Yardstick of 93.5 to calculate a DC Yardstick.

In all bar Heat 2 and Heat 3 the IC's were outperformed overall by the skinnier lighter counterparts, and a yardstick to take back to clubs and combined events is 91 (over a triangular course).

Looking at the UK Portsmouth Yardstick (and basing conversion calculations on Lasers, 505's and Fireballs) it would appear that 860 would be a good Yardstick starting point for DC's in the UK.

However, Yardsticks are continually evolving (especially in a boat so early in it's development) so the more data we can keep providing, the more accurate these numbers will become.

jimc
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Re: IC (DC) Yardstick

Post by jimc » Sun Jan 13, 2008 12:40 am

Christian AUS wrote:it would appear that 860 would be a good Yardstick starting point for DC's in the UK.
On the other hand your 91 : 93.5 ratio would put the DC at 880 in the UK. The AC is at 873 in the UK, and I don't think the DCs will want to be gving them time just yet.

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Christian AUS
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Post by Christian AUS » Sun Jan 13, 2008 1:13 am

But that is chalk and cheese as the AC's sail windward return courses and hence their yardsticks really can't be compared over a triangular course. For a parity check with AC yardsticks we'd need to find average elapsed times around triangles or put DC's on windward returns quite a number of times to get relevant data.

Phil Robin
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Post by Phil Robin » Sun Jan 13, 2008 3:39 pm

Thanks for analysing the data Christian. Based on the UK Portsmouth Yardstick of 905, I calculate the DC number to be 881. This compares to Portsmouth numbers of 901 for the 505 and 879 for the FD. The UK IC committee are meeting early Feb and one of the agenda items will be to agree the initial PY number for the DC. It will be a starting point only as the PY number will evolve through returns made by clubs for races where DCs compete.
Phil
K 41 Conquest
GBR 328 Little Scarlet

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Christian AUS
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Post by Christian AUS » Sun Jan 13, 2008 8:20 pm

cool, well I was never confident with the portsmouth number (as I don't sail in that system) but I'm reasonably happy with 91 as a starting point for DC's in Australia (though more results will tell).

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Christian AUS
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Post by Christian AUS » Sun Jan 13, 2008 8:20 pm

cool, well I was never confident with the portsmouth number (as I don't sail in that system) and several people have corrected me now :oops: but I'm reasonably happy with 91 as a starting point for DC's in Australia (though more results will tell).

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PN for DC

Post by petermclaren » Thu Jan 31, 2008 3:39 pm

I have done calculations of a PN for the DC using the standard RYA method and assuming a number of 880 for the DC, compared with 905 as is published for the IC. I used all 6 races during the World Championship, but not the Invitational Regatta.

This method takes all boats and then discards the "poor performers" who are more than 5% slower than the mean of the top 2/3 boats. These poor performers are not counted in the later calculations.

My calculations showed the IC at 912 and the DC at 870. The PN for the IC is changed because the boats on average sail to their PNs, and so as the DCis faster than I had assumed then the IC appears slower.

However it can be seen that The DC would be around 860-865 for an IC PN of 905. As the IC PN is now "Suggested Trial Number" (due to few Returns in recent years - we've all been saling ACs!) any number relative to it is only going to be approximate.

860-865 is apparently faster than the AC at 873, but as Christian notes results are needed from both DC and AC sailing the same race on a variety of courses in a variety of wind conditions before any real comparison can be made. So much depends on the windspeed, angle of reaches, legth of legs etc. that which boat comes out on top is likely to be down to the conditions on the day. just the problem we already have in trying to compare boatswith asymmetrical spinnakers and those without, dinghies and catamarans, dinghies and keelboats etc. etc. etc.

The first step is to establish a number from which DCs can race, andthis looks like arpound 860-865.

Regards,


Peter

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