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"LK" ROUTING SOFTWARE ONCE AGAIN PREDICTS THE WINNING ROUTE !!
In Pacific Cup 2004, 'Inspired
Environments,' a Benetau 40.7 using LK's "Offchart Racer" routing software,
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. This year, in Pacific Cup 2006, 'California
Girl,' a CAL-40, took a much more southerly route then the rest of Div A and finished way
ahead, some 21 hours ahead of the competition. Just after the Div A start, we applied LK's
routing software to predict the winning route and posted it on the web, with updates that
showed California Girl following our route day after day and pulling ahead to an equally
decisive win, precisely as we predicted.
The overall winner was Lightning, a
Santa Cruz 52 in Div E. Lightning got an early lead by going well south of its main
competition in the first few days, and was never caught. The graphic below shows her
reported positions (numbered boxes), compared to our routing solution for SC 52 polars.
Lightning tracked very closely to our optimal (red) route in the first couple of days, and
went a bit further south in the next couple of days. This took her closer to our
"green" route, a few hours slower (see times in box), but still quite a bit
faster than all routes to the north. |
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| CAN YOUR SOFTWARE DO THIS ?? CLICK HERE TO
CHECK |
| ROUTING SOFTWARE IS SO EASY TO
USE, AND WORKS SO WELL, THAT NO ONE SHOULD LEAVE PORT WITHOUT IT. IT IS MOST EFFECTIVE
WHEN USED ONBOARD, SO YOU CAN RECOMPUTE THE ROUTE FROM ACTUAL POSITION AND USE UPDATED
WIND FORECASTS, BUT EVEN PRE-RACE ROUTING CAN PUT YOU IN THE RIGHT PLACE FOR FIRST 6-7
DAYS, WHICH ARE OFTEN DECISIVE . CONGRATULATIONS TO 'BASIC INSTINCT,' WHO USED OUR PRE-RACE ROUTING IN DIV
C AND FINISHED 2ND IN DIVISION C AND 3RD OVERALL!! |
| Before the start, we
predicted the Division "A" race, using Cal-40 polars. This pre-race forecast is
included at the bottom of this page. The images that immediately follow are intermediate
reports, comparing actual to predicted postions, with the most recent date first. |
GENERAL
NOTE ON THE METHOD OF ANALYSIS USED BELOW |
| This page follows the Division "A" race for the Cal-40's and
other July 3 starters. Below we use the predicted routing for a Cal-40, using Force 4
tactical software and the high-resolution 14-day wind-prediction file from Local
Knowledge. The wind file has an internal resolution of 0.5 deg, with timepoints every 3
hours. The colored wind vectors shown are spaced evenly to show winds overlaying the chart
on display, they DO NOT represent the resolution of the underlying wind file. LK's
routing engine is unique in computing both a quickest, optimal route (the red route shown
below), plus other routes for comparison. This computation used Cal 40 polars and was
taken to begin at the position of the Lightship at 1400 hours, PDT (the router predicted 2
hrs 45 minutes to reach this position from the start at 1115 in SF Bay). The optimal (red)
route dips immediately to the south of the rhumbline and great circle route in order to
avoid a region of high pressure due west of San Francisco (see graphics below), but
eventually crosses back to approach Hawaii from the northeast. The red route is predicted
to take almost 272 hours, corresponding to a predicted finish 11 days, 10 hours after the
start, or on July 14 at 2100 hours. (Winds in the second half of the race turned out to be
somewhat lighter than the original forecast, so the race took a day longer.) Times for the
comparison routes are shown in the 'Best Course Comparisons' box (color-coded to match the
route). You can step through intermediate times with the router, which shows predicted
boat position at that date and time as a black dot on each route. The right column then
shows distance to destination from the black dot on each route. |
THE END
GAME: COURSE CORRECTIONS AND RACE AS REPORTED ON JULY 13, 2006 |
| Our analysis of earlier days (below) has compared reported positions
of the Cal 40's to our Force 4 routing solution, computed at the start of the race with
the "Local Knowledge" wind prediction we supplied to competitors. It has been
striking that California Girl has pulled away from the fleet by closely following Force
4's optimal "red" route. The wind file was computed on July 3 for 14 days,
enough to complete the routing to Hawaii, but the question always is how long the
pre-start routing will hold up. In our past experience the "LK" forecast is good
for at least a week, and that seems true in the present race as well. It is important,
however, to periodically recompute a routing from actual position, whether or not the boat
is able to update the forecast, as there are a variety of reasons why the boat may not
quite be where anticipated at the start. The graphic below uses the original forecast and
recomputes a routing solution from the actual position "6" of California Girl at
0900 on July 9, about 6 days into the race. The black dots show predicted boat
position on each of the routes at 0900 on 7/13/06, when California Girl reached position
"10." Winds are shown at that time as predicted by the original forecast. The
reported postions continue to track the pre-race optimal route through "8,"
reported at 0900 on 7/11/06, so the original forecast has correctly predicted the winning
route through day 8 of the race. After that California Girl has chosen to go south of the
original route. At this point in the race, having opened more than a 100-mile lead by
taking the optimal route around the Pacific high, routing is no longer so critical, and
one could simply sail the rhumbline the rest of the way without losing much ground. It is
better of course, to reroute with fresh wind predictions. Without access to the internet
one can only get a low-resoluion wind file, and only for a few days, but that is
sufficient with only a few days to go. In the next graphic we recompute the same solution
using an updated wind file from LK, also at 0.5 deg resolution but compiled on 7/9/06. |
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| Using the updated forecast at 7/9/06, the reported track of
California Girl once again follows the Force 4 optimal route (graphic below). Compared to
the route using the old forecast (above), the revised route dips south a bit, and is
predicted to take almost 4.5 hours longer. Comparing the winds on this and the above
graphic, the revised winds are somewhat less in magnitude, and are shifted a bit, to blow
more towards the southwest. However, the wind forecasts are not all that different, even
though compiled 6 days apart, and the original routing has held up quite well. |
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THE RACE
AS REPORTED ON JULY 9, 2006 |
| Below we compare the track of California Girl (lower set
of numbered boxes) to that of Green Buffalo (upper set of boxes). On the sixth day,
California Girl has continued to follow Force 4's red optimal route, whereas Green Buffalo
has wandered and finally changed course to the favored south. She now lags far behind,
losing more ground each day. California Girl now has a significant lead on Division A and
is unlikely to be caught. |
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THE RACE
AS REPORTED ON JULY 8, 2006 |
| Below we compare the track of California Girl (lower set
of numbered boxes) to that of Green Buffalo (upper set of boxes). On the fifth day,
California Girl has continued to follow the red optimal route, whereas Green Buffalo has
deviated even further north from the (already) slower blue route. As predicted, California
Girl has moved into the lead. |
 |
THE RACE
AS REPORTED ON JULY 6, 2006 |
| Below we compare the track of California Girl (lower
set of numbered boxes) to that of Green Buffalo (upper set of boxes). On the third day,
California Girl continues to track fairly well the red optimal route, whereas Green
Buffalo is closer to the blue route (predicted to be some 2.5 hours slower). Both boats
are slightly behind the predicted position for this timepoint (black dots). This could be
because the wind prediction is slightly off, the polars are slightly off, or because the
boats are not quite sailing the routes precisely. At this point Green Buffalo is
still, as predicted, slightly closer to the destination, but this is predicted to change.
The wind predictions at this timepoint (0900 on 7/6) show more velocity to the south,
which will enable California Girl to pull ahead in the next couple of days. |
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THE RACE
AS REPORTED ON JULY 5, 2006 |
| The graphic below shows predicted boat positions (black dots) on each of
the routes at 0900 on 7/5. The right-hand column of the 'Best Course Comparisons' box
shows distance to the destination from the black dot on each route, so at this point the
boat on the optimal route is about 1767 nm from the finish, further than predicted
positions on some of the comparison routes. As the race develops, however, the boat on the
red route is predicted to pull ahead and finish hours ahead of boats which take the other
routes. The reported positions of California Girl (boxes "1" and "2")
indicate that it is approximating the red route, and position "2" is just where
Force 4 predicts it to be at this time (interpolate between black dots on blue and red
routes). Although the Pacific Cup website indicates California Girl to be behind at this
point (based on distance to the destination), the routing solution indicates that it
taking a route that will ultimately put it in the lead. |
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| The graphic below shows the overall routing and the alternative
display of the 'Best Course' form, which indicates the minimum and maximum wind
encountered on each route. The optimal route finds winds of 12 knots or more, whereas the
yellow route passes through wind as low as 1 knot. These windspeeds are reflected in the
predicted times for each route. |
 |
PRE-RACE
ROUTING ANALYSIS AND FORECAST FOR CAL-40'S |
| The graphic below shows our pre-race forecast, with predicted boat
positions (black dots) on each of the optimal (red) and comparison routes at an
intermediate time (0839 on 7/7), and predicted winds at this date and time (the wind
display resets as you step through the intermediate times of the routing solution). Below,
the right-hand column of the 'Best Course Comparisons' box shows distance to the
destination from the black dot on each route, so at this point the boat on the optimal
route will be about 1445 nm from the finish, or about 16 miles closer than on the green
and blue routes. In earlier timepoints (see daily analysis above), the boat on the optimal
route is further from the destination than on other routes. |
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| The graphic below shows predicted locations a couple of days later, at
0557 on 7/9. At this point the high pressure zone has moved west and south, continuing to
plague the boats on the northern routes, and the boat on the red route has opened up a
lead of about 25 miles on the boat on the blue route (which differs from the red route
only in the beginning portion), and about 55 miles over the boat on the southerly, green
route. |
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| Force 4 was equally successful in predicting the winning route for CAL-40's in
the 2003 Transpac: TO SEE, CLICK HERE |
| For more information about
the Force 4 router, see the developer's article in Seahorse
Magazine. For more information about Force 4, see Force 4
Features. For other races, see Race Recaps and Previews. |