For those who may have an interest in the 18 Square, please feel free to contact me, as I was the Class Association Secretary from 1983 until (approximately) 1994.
Yes there were two (2) categories of Square.
Category I was any boat under 330 lbs. all up weight - or any boat whose mast circumference was greater than 21 inches.
Category II were boats that we 330 lbs. or more in weight.
At the time the class was active - late 1970's through the early 1990's, several production boats were available, as well as a series of homebuilt boats. NACRA and COYOTE were the "production" boats - with NACRA being the only "factory" production boat available. The COYOTE was a design that was produced in very limited numbers, and by several different owners of the hull molds.
As noted, the hombuilt boats were built by various people, and the most prevalent were the boats (3mm ply and ply/honeycomb construction) by John Lindahl of Michigan. John's designs still live today and as I recall a set of his hulls might still be available on the "A" Class Association classified ads. His plans are also still available for home building through the Gougeon Brothers (WEST System) library of plans. Brad Johannson (a builder from Maine and the Northeast at the time) also produced a series of boats that were often sailed by himself and Bob Bergstedt. His boats were eitehr ply or cedar strip. David Ward, Denis Palin, Ted FLack and a few others were involved to some extent in home building during that time. On the west coats, Gino Morelli, Fred Roland, Bill McClellan, Ken Wellman, Craig Riley and John Brink round out a series of early builders/designers. By the way - for the record, it was the Roland boys who initiated and fostered both this class and the NACRA (factory, at the time).
Because the class was an "Open and Development" class, boats were made from Kevlar, Klegecell, Orcon S-Glass, wood (ply and strip). Contrary to previosu posts - carbon fiber WAS NOT the norm and only near the end of the class heyday, did it begin to appear - but in the form of rudders and boards.
Tom Roland, Fred Roland, Skip Elliot, Roy Seaman were all involved in the effort to build this class, Fred being the dominant developer of the actual 18 Square Class.
CLIMAX was the Morrelli boat, and Jim Hansen was teh designer of the COYOTE. Also a point of interest .... Gino Morelli was the first (known) builder to cant the hull boards. At first it was suggested that the tilt to the boards was to offer a way to make the boat point better - but later confirmed by Gino they were simply tilted to clear the side shrouds when raised !
Today, the thin NACRA spar would need to be replaced by carbon or a stronger wall section if the boat was to be fitted with a spinnaker, and there might be aneed to further reinforce the bows of any boats since NACRA (at the time) simply used half tubes of cardboard to run forward to stiffen the hulls. Also NACRA (then) was known for oil-can sides that weren't corrected until about 1987-1988 when NACRA started using foam sandwich construction.
I still have my old 1983 SQUARE, and while it hasn't sailed in a few years, it still can scare the bejesus out of you when the wind picks up. Optimal performance for a Square is flat water and 12 -16 mph winds, as that is when the wider beam comes into it's own. If you have ever sailed a Tornado, just imagine an extra 1 or 2 feet in beam width. Makes choppy water very flat when hulls are that far apart.
Also - contrary to the theory that the "WING" did in the class - it was eventually beaten boat for boat by John Lindahl on a soft sail Lindahl Catamaran Design (LCD)boat, the two major impacts on the class were 1) the NACRA factory pulled out of making it a production (special order) boat, ..... and 2) the decision by many owners NOT to trailer their boats - either to the next lake or to the Nationals due to beam size of 11 to 12 feet.
That's a brief history and background. Please feel free to contact me for specific questions relating to the class.
Dick Lemke
Dick.Lemke@co.dakota.mn.us 
