Plans are available (I think) through Gougeon Brothers plan service, but hull is really an "A" Boat design - and needs a bit more displacement to support wider beam and bigger rig. John Lindahl lives in Fennville Michigan and you can probably do a search and contact him directly. Denis Palin from Houston Texas is another who had recently build an 18 Square. Bobby Bergstedt in New Jersey might still have contact with Brad Johannson who was also a custom builder. NACRA ended 18 Square production in the late 1980's - early 1990's due to slow sales and an influx of "custom" boats. Originally they were SolCat hulls, then they moved to the 5.2 hulls at 10 feet of beam, and as the class grew, the Roland Brothers started building their own hulls called NACRA which eventually were bought out by Performance Catamarans (Frank Butler). Class sails were made by Skip Elliott, Henry Bossett and Randy Smyth - with a few home-growns ones included. Coyote molds were purchased and produced for a short period of time in Texas by Chris Kilbourn (last phone number I have for him is 214-224-8441 - work number). Not sure what he did with the molds. Gino Morelli and a few other west coast sailors did some one-off's back in the early 1980's - but never knew if they kept the molds or not.
The 18 Square IS NOT a 5.5 - or a 5.8 set of hulls.
They are specifically designed 18 foot long and the beams started at 10 feet and grew to 13 feet, then settled back at 11-12 feet. Masts were usually 30-32 feet and mainsail was 18 sq. meters or about 194 square feet. Weight of boats ran from ultra-light 260 lbs. up to about 400 for glass production boats. Class had Category 1 and 2 and raced together. Solid Wing sails were allowed and WILD TURKEY owned by Craig Riley of Calfornia was our class "poster boat". Lack of new builders also contributed to the decline of the class. Boats were either taken apart or tilted for trailering. Large fleets were located in the North East, Michigan, Virginia, Florida, Texas and California. A few others were scattered around the country - Tennessee, Carolinas, and even South Dakota ! There was also a bit of 18 Square activity in Australia and in Europe for a time. Germany, specifically, had a group of Squares as did the U.K.
As former Class Secretary I welcome any questions.
