I live in Maryland. I sail in the Patuxent River and Chesapeake Bay. I mostly sail recreationally but race in a local weekly series and a few times a year in local Chesapeake Bay regattas (with CRAC). I sail a Nacra 5.5 SL with Spi.

As a comment, even if everyone who is registered on this forum replied, you would be getting only a very small sample of cat sailors. There are over a dozen other boats on the beach where I keep mine. One travels all over the East Coast to race, but never posts here. The others are just recreationally sailed. Some often, many rarely. And the local racing fleet, CRAC, has many more members and only a handfull would post here. But you should be able to get a demographic distribution you were seeking (for what purpose?)

Racing Fleet: Catamaran Racing Assoc of the Chesapeake (CRAC)
Recreational Home Fleet: Southern Maryland Catamaran Club