sentences:  The International Offshore Racing (IOR) rule supplanted the previous rules in 1970 to provide a fairer basis for handicapping racing yachts.This rule promoted the use of fin keels and blade rudders.This rule was augmented with the International Measurement System (IMS) to assure safe designs for extreme conditions, following the disastrous 1979 Fastnet Race in which only 86 of the 303 participants finished owing to failed equipment and loss of 19 lives and five boats.