Starting Line Display
Advantage Level 3 adds an innovative "starting line" display to the new Buoy Racing Menu. The inset form can be resized and moved around to allow a view of both the overall course and the line.
The example below shows the start of an upwind leg (to mark "1"), with the boat below the starting line with ends at marks "2" and "3." You simply click the ends of the line and the upwind mark to bring up the inset form, which reorients the line to the horizonatal axis and displays boat location and heading relative to the line. The display shows wind (black vectors above the line) and current (blue streamers) near the line, and the rhumbline to the mark (dotted line from boat extending to top of display). It also includes a clock that can set to count down to the start (buttons set to 5, 10 or 15 minutes, and the arrow key can be used to set any time). Set the time and then hit the 'Start' button to start the countdown.
The Starting Line Display also computes a number of quantities relevant to the start. As shown below, it computes the time to the line at present heading and boatspeed (shown just above center of line, 2:01 in the example) and projects the track to the line (dashed-dot line). The track may differ somewhat from the heading since the calculation takes variable current into account. The display also calculates the minimum time required to reach the ends of the line (here the times 2:40 and 1:52 shown at the far left and right of the display), and determines the favored end of the line. The end with less upwind distance to the mark is shown in red, and the less favored end in green. The number (0.1) above the red (favored) end is the difference in upwind distance (due to the fact that the wind direction is not perpendicular to the line). In this example the left end of the line is 0.1 nm closer to the destination mark.
The Starting Line Display expands or contracts the scale depending on how close the boat is to the line. The computations track time to the line whether the boat is below or above or some distance to the sides of the line during the prestart manuevers. In the example below the boat has gone above the line and is in the process of going back. The display shows that it will cross the line in 3:27 at present heading and boatspeed, but could reach the left end of the line (red mark) in just 2:54 at maximum speed. Of course, all of these computations are refreshed every couple of seconds, and will change as the wind changes (and all include the effects of current).