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Size Counts

New Rules

Size Counts

A study of findings from the proposed National Keelboat Rating System

Having run the fleet ratings against IRC #’s, there is a trend with the 40 ft yachts creaming it on IRC “mark-up”. The pattern seems to be IRC plus 5% for most Pre-2001 C/R’s in mid size range 30 to 35ft., with larger 38-42 ft. range in a comfortable 7 to 9%+ mark-up. But then past 43 ft upwards, the mark-up drops sharply back down to 4-5% range unless has radical SA/D relationship such as the TP52 class.

As discussed in previous chapters, most post-2000 models of 34-45 ft Performance Cruisers * already have terrible “mark-up’s” in range 1 to 2.5% due to “deemed IMS/IRC speed” being greater than actual achievable with rated SA/D.

If run a normal model, with yachts of different size but similar DLR and SA/D, would expected them to rate with similar relationship, and not fluctuate on size as per IRC mark-up. It is not consistent, and asks the question why is happening? It would require a bit of reverse engineering as slows down the 38/42 ft’ers but speeds up the < 37 ft & > 43 ft + yachts, but goes back to earlier comments that IRC was designed for 30 to 40 ft yachts…..It cannot be to adjust for wind pressure, as proposed rating # already has already allowed for same. Perhaps the reasoning was for the top of [then] fleet with most expensive & prestige yachts with big campaign costs, being guaranteed that would not be taken out of the silverware by a mom & pop 34 ft weekender! Also would help to ensure that big teams pay their certificate and re-validation costs…

What factor would do this, as is ending up with a bell shaped graphical curve? It could be on lines of:

Secret factor (metric) = sqrt ( (Immersed waterline -12)^2)

This would give results per below, and would be likely outcome of said formula if included in rating!