Nice boat! There is a class association website: http://www.holder20.com/
IIRC, the Holder 20 was the humble beginning of an amazing sport boat, the Ultimate 20. http://www.u20class.org/
I believe the story was Moore's sailboat shop somehow wound up with the Holder 20 molds. A group of (mostly) Santa Cruz sailors (Jeff Canepa of Tornado cat fame, Jim Antrim of sport boat fame, and Larry Tuttle of 505 fame) gave the Holder 20 a diet of steroids, or some kind of naval architect magic, and out came the Ultimate 20.
The original version is a great family lake boat.