I was glad the other evening to attend one of Kame Richards’ famous talks about tides in the Bay at the Bay Model in Sausalito. It was a real eye-opener for a novice racing sailor. While I’d been to the model once or twice before, Kame showed how the currents in the Bay work from a sailor’s perspective. He should know — he is the proprietor of Pineapple Sails in Alameda and a long-time racer of and Express 37. The talk was illustrated by analysis of a number of areal photos, and then we went out to the model to see the water in action.
- Currents rule, and they are cruel.
- Sea state. Even if you can’t make out a current line, look for areas of transition from white caps to no white caps. Water flowing to windward will be smoother.
- Counter currents. Nearly every point generates one. Look for it. Learn to snuggle up to the city front, especially when heading W. in a flood.
- On Westerly days, the wind fans out so as to appear to be coming from Pt. Blunt no matter where one is along the E. shore of the Bay.
- Alcatraz 1. The wake of Alcatraz has a huge opening angle, and extends for miles. Look for it! The tide line to the south runs from Alcatraz straight toward the isthmus of TI-Yerba Buena.
- Alcatraz 2. The dirty air behind Alacatraz covers a much small angle than the current wake.
- TI. The dirty air behind TI extends out pretty far. We got burned by this in this year’s 3BF, among other things.
- Wind vs. current. The domant wind direction in the central bay is along a line from the South Tower to Alcatraz. The dominant current direction in the middle of the Gate is WSW. These don’t line up. Need to think about what that means.
- Keep an eye on commercial fishermen. They will often take the most efficient routes.
- Angel Island. The dead zone is big, big, big. But you knew that. Respect the hole!
- The ebb will start along the shore before the flood in the center is stopped.
- The same applies outside the Gate. No matter what the tidal state, you can find a counter-area if you need one.
- Slack water isn’t slack. It just means that the net flow out the Gate is zero. It is really still flowing out in some areas, in in some others.
- In wet winters, the momentum of the surface fresh water from the rivers can carry water well down into the South Bay, well past the time when the ebb ‘should’ have stopped.
Styrofoam disks suspended from poles on thread indicate current flow. Here, the counter-current to the main ebb tide just outside the Gate is easy to see.