RaceTools twdCompute is a calculator that computes solutions for True Wind Direction based calculations. This tool is particularly useful during sailboat racing to quickly compute tack headings during racing, and to compute starting line bias prior to the start.

RaceTools twdCompute is simple to use. The Mode buttons on the bottom of the screen select which of the two modes, 'TACK HEADINGS', or "START LINE" is desired. While twdCompute is running, the data entered in each mode is preserved while switching back and forth between the modes.


TACK HEADINGS Mode
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After selecting the current True Wind Direction (TWD), the Port and Starboard heading compass headings may be computed by adjusting the True Wind Angle (TWA). By pressing the 'TWA' button, the computer is configured to compute the Opposite Tack compass heading from a current heading that is selected by the user.

START LINE Mode
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The Square LIne compass heading is initially computed by selecting the compass heading that is determined while sailing the start line on either port or starboard prior to the start. When the link indicator symbol next to the TWD header (white in color) has a small rectangle showing inside the top and bottom white marks, the TWD will change when the start line compass heading is changed. After the initial line is determined, the TWD value may be changed each time a 'wind shot' is accomplished to determine the actual true wind as it oscillates prior to the start. When the TWD value is changed by the user, the white rectangle in the link indicator symbol will disappear, and the TWD value will no longer change if the Start LIne heading value is changed again. To lock the TWD back to the start line heading again, simply touch the link indicator symbol and the rectangle will appear again.

Changing the compass heading values
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For each mode, the bottom sets of numbers may be changed by using the blue buttons below the digits. There are 3 sets of buttons to change each set of 3 digits. Each set is labeled '^' and 'v' to indicate 'increase' and 'decrease' respectively. These buttons are used to increase or decrease the heading values on the displayed digits.

For each of the sets of 3 buttons,
- left buttons change the heading value by 90 degrees.
- middle buttons change the heading value by 10 degrees.
- right buttons change the heading value by 1 degree.

Price includes all future updates to this application.

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GENERAL FEATURES:

- compute port and Starboard headings from TWD and TWA
- compute Opposite tack heading from TWD and current heading
- compute square line wind direction from Port or Starboard heading of Start Line
- compute line bias after square line is set by changing TWD

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Default settings available in the iPhone settings:
- Button sounds On/Off

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