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Coast to Bermuda Races
Various races to or from Bermuda are held every year. These include:
» Marion
to Bermuda
» Newport to Bermuda
» Annapolis to
Bermuda
» Bermuda One Two
Unlike the Marblehead-Halifax race where tidal currents play
a key role, racing to Bermuda is hardly affected by tides
but is
significantly affected by the Gulf Stream. Having good knowledge
of the Gulf Stream at the beginning of the race allows the
navigator to formulate a strategy for crossing the stream
and taking
advantage of current eddies and meanders. Luckily the stream
does not change
rapidly so updated stream information during a race is usually
not essential. There are a number of free and commercial sources
for Gulf Stream
information. A good starting point is the Newport-Bermuda
Gulf Stream and Weather page.
SailFast™ accepts
GRIB current forecasts in addition to predicted wind. Having
both current and wind GRIBs will yield the most accurate optimum
routing. However if you don't have a Gulf Stream current GRIB
you can still use SailFast's routing capabilities effectively.
Merely set the SailFast™ "finish" waypoint
to the desired position for entering an eddy you are targeting
or the stream, and the best course for getting there will be
determined.
Once through the stream repeat the process to the next eddy or
the finish.
Gulf
Stream current GRIBs are not as readily available as regular
wind forecast GRIBs. While some models exist for making automated
current predictions, often Gulf Stream forecasts are developed
manually by experience meteorologists. One source of Gulf Stream
GRIBs which has been validated to work with SailFast™ may
found at www.marineanalysis.com or
www.commandersweather.com.
Below
is an example of a Newport-Bermuda routing
solution. Both wind and current arrows are displayed. The optimum
route first picks up the favorable East side of an eddy and then
rides a long section of the stream before heading South towards
Bermuda. The predicted ETA to the finish is 82.3 hours. The time
between the blue isochron lines is 3 hours. It took
slightly under 3 minutes to run this optimum routing simulation.
(Click
any image for a larger view.) 
The optimum route takes a big jog East to take advantage of eddies
and the stream and we a sailing a lot more distance than a
rumb line course. What happens if we sail closer to the rhumb
line?
Here
we have added an additional boundary line to restrict where
we allow sailing, and the wind arrow display has been turned
off so we can see the current better. The boundary lines
are magenta dashed lines. Now we force
the
crossing
of the
stream
to
be farther
West.
The optimum route still takes advanatge of the first eddy,
but once through the stream a much more direct course to
the finish is sailed. The ETA for this route is 82.4 minutes,
just 6 minutes slower than the fastest course! All
things being equal, I'd choose this course since it covers
a lot
less distance and doesn't require hitting the stream just
right.

Finally,
let's see what happens if we ignore the stream altogether and
set the current=0 for the simulation. Now we have the original boundaries
and just the wind arrows. The best course is now close to the
rhumb line, and it is only deviating due to wind changes.
The ETA is 85.9 hours. This result isn't very
meaningful
because
there
really is a significant Gulf Stream to contend with, but understanding
the course with the best wind can be instructive.

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