WIND ANALYSIS OPTIONS
Level 3 provides a number of tools to monitor and analyze wind. In buoy races, you can turn on the Track function with the 'Show Winds' option, which adds a wind vector to the track, as shown below. This gives a quick visual of how wind changes, both over time and from point to point (a correlation that is missing in the Stripchart record of wind strength and direction). Where wind shifts are primarily due to location (rather than time variation), this display can be a useful guide when you repeat a leg, to see what happened last time. This display is also useful in long-distance racing, overlaying the display of predicted wind from a grib file or user wind model. You can compare predicted to actual wind, helping to decide between wind models and modifying a model if required. A track file can be reloaded at a later date, to study what happened in the race. As you pause the track, the display time will automatically reset to show wind and current predicted for that time, as well as the wind vector showing measured wind.
The 'Winds Along Route' option displays predicted wind at each of the interval points in a routing solution (see below). This gives more insight as to the data driving the routing solution (both for the optimal and comparison routes).
You can zoom in to a portion for more detail and step along the route to see where the boat is predicted to be at a given time along the various routes. In the graphic below the black dots on each route show predicted position at 0557 on 6-11-2007, and the 'DTG' column shows distance to the destination from the corresponding black dot. The 'T' option automatically resets the display time to the intermediate time, so you can also display wind and current as predicted at that timepoint.
It can also be useful to monitor the minimum and maximum windspeeds to be found along various routes. If the minimum wind is very low (say under 4 knots), the routing can be quite sensitive to the accuracy of the forecast. At the high end, boat speed doesn't increase (for most boats) once wind gets above 30 knots, and at higher windspeeds increased wave action and difficulty in steering will have a negative effect on boatspeed, not to mention the likelihood of damage (and ultimately danger to the crew). Level 3 includes the "T/W" option button on the routing result form, which display the min and max wind found at the intermediate timepoints on each of the optimal and comparison solutions (see below). If two routes are not too different in time, but the "optimal" goes through either very low or very high winds, you may be better off with the alternative. The Level 3 routing control form also allows you to specify a minimum and/or maximum allowable wind for the routing, thereby resulting in an optimal route that lies within the specified range.