Laylines

In sailing; Laylines are COG vector lines showing the course the boat will take when sailing at the optimum angle to the wind, on either tack. The laylines will show whether the boat will reach the intended destination on the current tack, or if another tack is required to meet the destination. Sailing to the target wind angle maximizes your Velocity Made Good (VMG) resulting in your boat traveling along the layline.

LaylinesChart app LaylinesLaylines show the course to a destination point based on True Wind Direction (TWD) and the selected Sail performance option:

  • Sail performanceMirrored TWAMirrored TWA (True Wind Angle) — This setting assume the boat is sailing to the optimum wind angle. The current boat heading is used as the active layline (adjusted for tides if the options has been enabled and with estimated leeway if not) and then mirrors the current TWA to show the opposite tack layline.

  • Sail performanceFixed AnglesFixed Angles — The laylines use fixed upwind and downwind angles. For details refer to: Fixed angles laylines

  • Sail performancePolarPolar — The laylines use a polar table which reflects the performance of your particular vessel. For details refer to: Polar laylines

Sail performanceSail performance settings can be configured from the Homescreen settings menuHomescreen > Settings > Boat details.

The chart app’s Laylines settings menu provides further options (Chart app > Settings > Laylines) which allow laylines to account for tides and leeway and to display wind shift graphics.

Figure 1. Example upwind laylines

  1. Port vessel layline.

  2. TWD & TWS.

  3. Tide direction and speed

  4. Starboard destination layline.

  5. Starboard vessel layline

  6. Destination waypoint.

  7. Port destination layline.

Note

Laylines show the predicted COG (Course Over Ground) when steering to the optimum upwind or downwind angle. Due to tide and leeway; you will often have to point the boat at a different angle to the layline in order to travel along the line. Optimized steering guidance is available on the Sailing page of the Dashboard app.