It was originally designed so that it could be home-built by individuals.
Each hull is made from two pieces of plywood glued together in a vee shape position,
then forced into a jig that bends them into a gracefully curved hull.
The technique is called "tortured plywood".
These are the detailed building instructions from Houlton Boat Company 1979
If you are Jerry Houlton I'd love to hear from you
Step 1: Tornado Catamaran Olympic Trials 1967 AYRS Report
It was a major leap forward in performance, outsailing the other contenders by a wide margin.
After 40 years, many believe that the design is perfect for a two-man cat to be sailed in somewhat rough water.
The boats built today have a rig that's larger and lighter, and the hulls are usually made from carbon and honeycomb, but the shape of the hulls hasn't changed at all.
It's the standard by which 20 foot catamarans must be judged, and you can build your own from plywood.