Driving out Point San Pedro Road in San Rafael there are two launches. Both of which require a minimum of 2.5 ft of water to be sailable.
Loch Lomond Marina
While the launch requires you to walk over some large rocks this can be a fun Wing Foiling and Kiteboarding sport. Usually a little too light for windsurfing. Parking is in the south west corner past Andy's Market.
About 1 mile past Loch Lomond Marina is Brick Yards. Its a High Tide spot but also a pretty safe place to sail as any trouble largely has you getting blown back to where you started.