We have several lakes in or (relatively, this is Texas afterall) near San Antonio, several of which are large and open enough to permit sailing. Those lakes would be:
Canyon Lake (8,240 acres),
Medina Lake (5,575 acres),
Choke Canyon Lake (26,000 acres) and
Lake Buchanan (23,200 acres).
There's also even smaller lakes like
Calaveras Lake (3,624 acres),
Inks Lake (1,200 acres) and
Braunig Lake (1,350 acres). And for grins, you can access information on
over 170 other Texas akes via our Web Guide, as well.
As far as racing clubs, or clubs in general, check out the
Clubs & Organizations sub-category of our Web Guide's Sailing & Boating section.