I'm sailing in a Classic wood boat regatta in Marblehead next weekend and they have a classic plastic division. Mostly Hinckley's, Bristols(any thing Ted Hood designed). I was wondering is the J-30 considered a classic plastic?

Probably not. My guess is this refers to plastic yachts made to look like the original traditional wooden design. If in doubt, ask the race organizers to provide a definition on what constitutes a classic plastic design in order to qualify to race in that class.