This is a screenshot of MaxSea, a weather analysis and routing software program that many of the boats use. The red icon is Great American III. The two blue lines, southwest of South Africa and in the Indian Ocean are ice gates. The boats are required to leave one point on each line to starboard. The two lines with many small boxes (each a time interval) show two routes. the northerly one goes through both gates. The southerly one was tried to see if by chance aiming at only the second gate would give an optimum route through the first gate. It didn't. the southerly route is exactly what the race does not want the fleet to do, since there are anticipated to be many icebergs in that area, and thus they put in the rule for the first ice gate, to keep the fleet further north. The many arrows are wind direction and velocity. A GRIB file (see www.grib.us) predicts the wind direction and velocity for the many different locations, over time, and then this is applied to the boat's polar file (a file that tells how fast the boat will go with what wind and what direction). Then it runs a simulation, and comes up with an optimum route.