OOPs, I skipped MORC which is the Midget Ocean Racing Conference. The MORC is a measurment rule has actually produced some of the big advances in yacht design that has filtered out into cruising boats. The whole concept of the early MORC rules were to produce racer cruisers. The rule required minimum headrooms based on length and real accomodations down below. (IMS started out that way as well.) The MORC rule produced such wholesome designs as the Tartan 27, J-24, S2 9.1, and Laser 28. More importantly, the J-24 was so revolutionary in its day that it spawned a whole series of non-rule oriented higher performance boats like the J-30, J36 (J-35) and Express 37. The idea of producing fast boats that were not designed to any rule quickly became popular and some of these non-rule oriented performance boats of that era were really excellent boats. (My own Farr 11.6 while not derivative of the MORC was still designed in that time when in the wake of the J-24''s success designers began designing fast boats without regards for any rule. In the case of my boat, many of the features that characterize the early IMS typeform show up in early form.)
MORC boats are less than 30 feet, and tend to have long waterlines, and a fair amount of interior volume. They do have expecially fine entries and so give up a bit going upwind or in a chop. Middle period MORC boats tend to be fractionally rigged but most are masthead rigged. Early 1970''s MORC boats have very small mainsails but most have very nicely propostioned sail plans. Really early MORC boats are often centerboarders (Tartan 27 Morgan 24, Soverel 28 being classic examples of that trend). Middle period MORC boats look like J-24''s, Kirby 25 and Kirby 30''s, Capri 25 and 30, Schockwave 30, J-29''s. Late period MORC boats look like S2 Grand Slams, 7.9,and 9.1, Capo 30''s, Schock 30/30 and so on.