The two handicap systems most widely used for club level yacht racing on the West Coast of Scotland work in slightly different ways. CYCA (Clyde Yacht Club’s Association) corrected times are calculated by multiplying elapsed time by a TCF (Time Correction Factor) but PY (RYA Portsmouth Yardstick) corrected times are calculated by dividing elapsed time by a thousandth of the Portsmouth Number.
This converter works by dividing a constant of 687 (or user-supplied value) by the CYCA Time Correction Factor (which is itself calculated by deducting the CYCA handicap in mins/hr from 60 and dividing the result by 60). It can be used to calculate PY equivalents for a range of CYCA handicaps and/or to calculate the ‘constant’ for known CYCA and PY handicaps, but should be treated as an aid to setting handicaps and not as an oracle.
The form calls a PHP script to print a table of PY equivalents for the selected range of CYCA handicaps (provided these are between -20 and 40 mins/hr) and any constant from 670 to 700.
The original default constant of 685 was established by comparing the published CYCA handicaps and Primary Yardsticks for ‘cruisers’ from the early years (1996 onwards) of the ‘new-style’ Portsmouth Numbers to provide a reference point for allocating numbers to boats listed by the CYCA and not by the RYA. Only Primary Yardsticks (being the best attested category of Portsmouth Number) were used, producing an average PYxTCF of 685 and a spread of 675–697.
Taking both Primary and Secondary Yardsticks from the 2002 ‘cruiser’ and ‘keelboat’ lists into account to offset the shrinking number of classes with Primary Yardsticks, but discarding the highest and lowest results (the Anderson 22 at a rogue 735 and either the J 24 or the Super Seal at 675), the average PYxTCF still came out at 685 and the spread at 675–702.
My latest update (based on 2008 figures) produces the revised constant of 687. With only four keelboats and cruisers (Flying Fifteen, J 24, Sigma 33 and Sonata) still allocated Primary Yardsticks, it naturally also takes the Secondary numbers (of which there are twelve) into account, but includes both J 24 and X 332 at 675 from a spread of 675–697.
Alternatively, if you know both the CYCA and PY handicaps for a boat, you can use this second form to calculate the ‘constant’ for that boat and analyse its meaning. Lower numbers (< 687) suggest that the boat does better off CYCA and higher numbers (> 687) that it does better off PY.
Neither of the PHP scripts will accept values outside a sensible range!
Current CYCA handicap listings (NB this paragraph written 2002?) range from about -12 (very fast, eg Volvo Ocean 60) to about 30 (very slow, eg Fisher 25, Kingfisher 20), but there are only three boats I know of below 0 and very few below about 5. My conversion script accepts handicaps from -20 to 40 (rounding them to the standard 0.25 min/hr increments) and constants from 670 to 700 (to the nearest whole number). Simple transpositions of fast and slow will be corrected.
The second script accepts CYCA handicaps (as above) from -20 to 40 and Portsmouth Numbers (to the nearest whole number) from 500 to 2100. Simple transpositions of the CYCA and PY numbers will be corrected.
For me, the 2008 update gives Fly a PYxTCF constant of 689, with the Impala’s current 956 Recorded Number being much closer than the old Primary Yardstick of 943 to its CYCA 16.75 . :-)
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