There's only 1 place that I know of. Lake Merritt boating center run by the city of Oakland.

Lake Merritt is a tiny pond in the City of Oakland. I think you have to take a class to rent their largest cat, a Hobie Wave. In this litigious society it's very difficult to rent anything.

http://www.oaklandnet.com/parks/programs/boating_hours.asp

Also, you may try coming out to Round TI this weekend. Meet at Crown Beach Alameda Sat morning. You never know, someone may need crew.