Hey Serge, welcome to the forum
What part of the Bay Area?
Berkeley has a couple of good clubs/schools, Olympic Circle Sailing Club (OCSC, OCSC Sailing School | Learn to Sail - San Francisco Bay Area | Sailing Lessons | California Sailing Club
) for larger boats, and the inexpensive treasure the Cal
Sailing Club (Cal Sailing Club - Cal Sailing Club \| Windsurfing and Sailing Lessons \| Berkeley Marina - San Francisco Bay
) for smaller boats.
Lots of others around depending on where you are (Alameda, SF, South Bay, Richmond).
Another option is to walk the docks/introduce yourself around the yacht clubs.
And lastly, try the Latitude 38 crew list (Latitude 38 Crew List
) they can be pretty good for finding a local ride. There are also a couple of other informal crew lists around the Bay Area.