Once a waypoint or route is activated with the "Goto" button, a "SailTimer" tab will appear on the Navigation panel. SailTimer computes the optimum sailing angles and target speed to the active waypoint using true wind speed, true wind direction, and predicted performance (polars).
The "Start" button will a create or insert into the current route and activate, a route with two legs. The legs represent the laylines. Laylines are the furthest you would want to sail without overstanding the destination waypoint. The route will include three waypoints: A start, layline and destination.
The tacking or gybing angles will be plotted on the position icon on the Chart window when "Show Sailing Angles" is checked. Wind direction is relative to North (True or Magnetic). Wind speed and direction can be manually entered or come from the instruments by selecting "Use Instruments". "Tack/Gybe" will invert the route. "Cancel Goto" will deactivate the waypoint and remove the temporary SailTimer route.
Note: Each time the "Start" button is selected or the wind speed or direction changes, the SailTimer route will be recreated and the active goto will be reset to the first leg.
The performance data in the Polars dialog can be modified from the "Defaults" which are representative of a popular 40' cruiser. Enter the projected boat speed (knots) for the true wind angle and true wind speed (knots). Enter "0" when a value is not known. Select the "Save" button to apply the changes and close the dialog.
True Wind Speed Calculator
Note: In order for SailTimer to be accurate, the wind speed and wind direction must be accurate. Polars provided by boat builders or designers make the assumption the boat has a clean bottom, new and properly trimmed sails, properly tuned rigging, and the actual displacement is the designed displacement. SailTimer is not a routing algorithm, but instead just a tool that will recommend a course and target speed to a waypoint. SailTimer does not compensate for external factors such as obstructions or current.