Bob (Robert E.) Perry wrote a very good, easy to understand article in Good Old Boat Issue: 83 - March/April 2012, Pages 24-25 explaining the detail of just what Andrew stated below.
The C&C 38 Mk.3 is one of the best examples I know of of this "designing to the rule's measurement points" which explains why the 38 Mk.3 has such sharp corners and flat sections in its underwater profile. By the time Rob Ball designed the 37/40 and the 34/36 these corners and flat sections were being smoothed out but are still obvious if you know what you are looking for. IDIOSYNCRACIES OF THE IOR BY ROBERT PERRY How rating-rule number crunchers shaped sailboats. I have been looking forward to writing this. If your boat was designed between 1970 and 1985 it probably shows the effect of the International Offshore Rule (IOR). Even if your boat was never intended as a “race” boat, the effects of the rule probably show. What is current on the racecourse usually creeps into the mom and pop boats. Kind of like a rear-deck spoiler on a Toyota. For this reason, it might be of interest for you to understand how the IOR worked and why it produced the hull shapes and rigs we have come to recognize as IOR types. *Article Number:* 5387 *Issue:* 83 - March/April 2012 *Page No:* 16-19 *Read Online:* Not Available Online Ken H. On 4 November 2014 13:40, Andrew Burton via CnC-List <cnc-list@cnc-list.com> wrote: > That flat area forward of the keel on many 70s and 80s C&Cs, including my > 40, was there as a way of fudging an IOR measurement point. The purpose was > to make the rule think the boat was slower than it actually was. The boats > do pound if you motor straight into waves, but heeled the hull presents a > much nicer shape to a seaway. > > Andy > C&C 40 > Peregrine > > Andrew Burton > 61 W Narragansett > Newport, RI > USA 02840 > > http://sites.google.com/site/andrewburtonyachtservices/ > +401 965-5260 > >
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