Yes there are .... Hobie Fleet 54 operates on the Upper Chesapeake Bay, Personally I'm a Fleet 54 member and keep my boat at Rock Hall Yacht Club(RHYC) in Rock Hall Md .... Dave Raughley, Bill Coulhgan, Barbie&Jim Dowdie and several others I know who are members of Fleet 106 sail out of Rehobeth Bay Sailing Center(RBSC). You will find my E-Mail address in my profile. If you send me you contact info I'll pass it on to the appropriate people. You may want to consider checking out RHYC at
www.rockhallyachtclub.org .... if you want to come by for a "look-see" that can be easily arranged. RHYC holds two regattas per year that maybe of interst to you, on June 20/21st is the "Annual One-Design Regatta" that along w/ many monohull classes also has starts for the A-Cat Class, "Open Class" and H14 Class (for the first time this year). And on Sept 26/27th a Div11 Hobie Points Regatta. These events are well supported by the local Beach Cat sailors. The "Annual Regatta" usually has an attendence of 90 boats total w/ approximently 30 boats being catamarans ... the Sept event should attract 30-40 Div11 HobieCatters.
Also check out the "Open" Class website,
www.sailcrac.com Mark Schnieder maintains that site and lists ALL of the local events in the mid-Atlantic area ...
Harry Murphey