Pacific Cup 2004 Routing
Aboard 'Inspired Environments'
Using our "Offchart Racer" routing software,
'Inspired Environments,' a Benetau 40.7, surprised all the handicappers and scored a
decisive victory in Class C by taking a route well to the north of the rest of the class.
The boxes in the graphics below show her reported position on successive days ('0' is on
June 30, '1' on July 1, etc). The first graphic below shows the routing solution using our
wind forecast from her position on day 1 (June 30) to the finish. The red line is the
optimal (fastest) solution, and the other colored lines are comparison routes which take
longer. The times for each route (in hours:min) are shown in the 'Best Course Comparison'
box, color-coded to match the route. Unlike all other routing engines, our router (also
used in tactical program Force 4) computes quantitative comparison routes to better inform
the navigator. The red route is slightly faster than (and almost identical to) the magenta
route, 1.5 hours faster than the black route and 13 hours faster than the yellow route.
Routes to the south, below the rhumbline and great circle route, are much slower.
The black vectors show predicted wind at the timepoint;
13:10 on June 30, 2004. The router computes wind at intermediate points and times from our
14-day predictive wind file. |
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| The graphic below looks at actual v. predicted boat
position reported on July 2 (box '2'). The program permits you "step" through
intermediate timepoints simultaneously on the optimal and comparison solutions. Here the
black dots on each route show predicted position at 13:10 on July 2. The actual position
of Inspired Environment ("IE") is just slightly behind the predicted position on
the optimal (red) route. The right-hand column of the 'Best Course Comparison' box shows
distance from the black dot position to the finish. At this point the predicted black
route location is about 3 miles closer to the finish than the optimal route, but it loses
ground over time. The wind display uses
both color and vector length to show predicted winds at 13:10 on July 2. The outstanding
feature ahead is the high-pressure "hole" directly west, near the bend in the
yellow route, which prompted IE's competitors to go further south. Our router, however,
took into account the "hole's" northeast drift, and computed a more efficient
optimal route that took this into account (see next graphic). |
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| By the time IE reached location '4' on July 4, the high
pressure "hole" had move northeast, putting IE in maximal wind on a starboard
jibe. Even the more northerly 'yellow' course skims by the high, although losing
considerable ground in the process. More southerly boats have a somewhat longer course, at
lesser wind. |
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| Now that rules permit racers to update wind prediction
files at sea, via the web, it is critical to acquire the latest data and recalculate the
routing solution periodically. The solution below starts from IE's actual position on July
2 and uses fresh wind predictions to update the route. Note that the subsequent position
points 4-10 now lie closer to the router predictions than they did for the solution based
on the original wind data (compare to first graphic above). The basic features of the
overall route don't change dramatically, but the corrections can be important in a race. |
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| IE's reported position on July 5 is now north of the
optimal route, and slightly behind the predicted position (black dot). At this point IE
was well below the high pressure region, but a bit more north than desirable. |
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| On July 8, IE is slightly south of the optimal route and
somewhat behind predicted position. Typically, there is a band of routes which take about
the same time, as with the magenta and red routes. The comparison routes give the
navigator a feeling for how much the boat can deviate from the optimal route without
losing much time (e.g., to cover a competitor). At this point, the black route has almost
converged with the red route, but a boat that followed it would be some 12 miles behind a
boat that followed the red route. |
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| WE HAVE ANALYZED ALL OF THE PACIFIC CUPS AND TRANSPACS
FROM 2000 THROUGH 2005, AND IN EACH CASE THE WINNING BOAT HAS FOLLOWED OUR PREDICTED
ROUTING. THE PROGRAM IS EASY TO USE AND YOU GET THE SAME RESULTS AS A PROFESSIONAL 'ROCK
STAR' NAVIGATOR. |