Darryl,
You guys down under have always been 20 years ahead of the rest of us when it comes to spinnakers. The 18s are just as fast as beach cats so the spinnaker design technology developed on them is directly appilicable to beach cats. I put a spinnaker on my first RC27 in 1983. The sail would fill and look pretty but the speedo and compass said nothing happened. I tried a few different sailmakers over the next ten years but no success. Finally in the 1990s a much flatter and narrower spinnaker began to work and today the spinnaker is a hot ticket. The Tornado going with the spinnaker has really educated the sailmakers about spinnakers for beach cats in the US.
Bill