Pete, those were 505's, they use a symetrical spinnaker (and pinhead main) because....they never updated their class rules to the new technology? Very fast boats back in their day, the 49'r has overtaken them in speed but they are still quite popular.
It is harder to run their setup, so maybe they like the challenge, ie. only the really good teams can handle it. They have a single trap, the crew is really busy with the spinnaker work. I had one a long time ago, 1978-1980 or so, loved it, but my girlfriend (crew) hated it. I finally sold it for a Flying Scot, which she loved, but it was sooo slow...at least there was room for a cooler full of beer in the Scot!
