The assessment of sail area was subject to its complex series of measurements, although much of that complexity arose by the myriad of formulas that had to be established to equitably rate a wide range of rig types (fractional versus masthead, and single masts versus two masts). In its most simple form, the rule component S was the square root value of total rated sail area (RSAT), itself a combination of mainsail and foretriangle measurements.
|The 1986 Half Ton Cup winner Cofica - the broken spinnaker pole was not a rating device!|
|l'Effraie (left and above)|
|Cascade during the 1983 SORC|
|The ketch rigged New Zealand Endeavour during the 1993-94 Whitbread Round the World Yacht Race|
|The typical rig of the early IOR years|
|The J41 Dazzler dropping her spinnaker at a leeward mark during the 1984 SORC|
|Wai Aniwa and the infamous 'shooter'|
The ubiquitous fractional rig first came to the fore on light displacements yachts from the mid-1970s, and had their first real success on the Farr 727 in the 1975 Quarter Ton Cup. But masthead rigs still remained popular through the 1980s, and maintained parity with fractionally rigged yachts for many years before technological advances and greater reliability saw the more flexible and adjustable fractional set up become integral with success at the top end of IOR racing in the late 1980s and 1990s.
|A fleet of IOR 50s displaying a mix of fractional and masthead rigs|