"Local Knowledge" Provides the Winning Edge In San Francisco Bay Racing |
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| Local Knowledge offers a range of PC programs at different levels, each incorporating our detailed hydrodynamic current model of San Francisco Bay, now the gold standard in SF Bay racing. The examples below are based on our "Force 4" tactical program, which is best used live onboard, monitoring the GPS and boat instruments. But our entry level "Force 2" program at just $200 contains the same current information, charts and many options to study currents and plan racing strategy. At an intermediate level, "Offchart Racer" has many of the tactical functions of Force 4 at 1/3 of the price. All programs come preloaded with BBS marks and courses. |
| We build detailed models to predict currents in race venues worldwide. Our PC programs enable you to study current in advance and plan race strategy. The graphic below shows typical flood current in San Francisco Bay, which often exceeds 5 knots. The current points shown in yellow are added at the user's option, at any location, to provide more detail in the race venue. Currents of this magnitude have a dramatic effect on the position of laylines, course selection and race strategy. In the graphic, the solid blue lines are the laylines in the absence of current at Blackaller Buoy (shown as "2"), assuming typical wind of 12 knots at 250 deg T. Due to the variable current, the actual laylines are shown by the magenta dots (if you sail at the optimal tacking angle and make the target speed, you will sail this corrected, curved, course to the mark). The "best tack" tactical solution shows that a starboard tack to the lower layline, followed by an approach along it, is more than 13 MINUTES faster than the port tack solution. These effects of differential currents are common in SF Bay, and will be a key factor in the 2003 Big Boat Series. THE ABILITY TO COMPUTE AN OPTIMAL TACK SEQUENCE IS UNIQUE TO OUR SOFTWARE! For more examples and details, see CAN YOUR SOFTWARE DO THIS? Our tactical software also perfoms more powerful and informative optimal routing. |
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| The graphic and tactical results are based on the PC program we have developed and refined for San Francisco Bay over the past decade, which has become a standard tool for most of the top Bay racers. This computes currents at any day and time, and at every point on the chart. This is the only program which can do this, and the only one which can be calibrated to actual sensor data from real-time NOAA sensors. Our programs integrate the current model with a full range of navigational and tactical functions, including the unique "VMG" display shown below. In this display the program shows the locations at which the boat can make optimal speed towards the mark (upwind in this case, or downwind) by circles of increasing diameter; the bigger the circle, the better VMG. Our "Force 4" program tracks your boat position onscreen and automatically updates this display every few seconds. |
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| Our Force 4 tactical program includes a powerful "best course" routing function, which searches all possibles routes from one point to another to find the quickest, and displays alternative courses for comparison. In SF Bay racing, coming west (upwind) against a flood, a common question is whether to use the current "shadow" of Alcatraz (the "cone") for current relief, or to stay close to the cityfront. This decision depends on a number of factors: time of day, strength of flood, wind speed and direction, and boat characteristics. The program sorts all this out for you and tells you just how much faster one route is than another. This solution assumes constant wind and routes purely on current, but the router works equally well in ocean racing with variable wind, as shown in the Volvo Race, Newport to Bermuda and many Pacific Cups and Transpacs. In the graphic below, the "cone" solution is represented by the blue line, and is 2 minutes slower than the red "cityfront" course. Note: times are color-coded to correspond to alternative courses. Our tactical program is the only one which can compute detailed courses along shorelines and around obstacles, and the only one which builds in a sophisticated model of currents. |
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