14.18 Laylines
Laylines are used in sailing to show how far the
vessel must sail on the current tack in order to make
the target waypoint after tacking, given present
wind conditions. Laylines are based on the True
Wind Direction (TWD) and xed or polar upwind
and downwind sailing angles. Sailing along laylines
maximizes your Velocity Made Good (VMG) to
windward.
Laylines are displayed under the following conditions:
• The Boat Type setting is set to one of the available
sailing vessels
• The vessel is under active navigation towards a
waypoint
• The layline path to the destination point is less
than 150 nm
• The angle between port and starboard laylines is
less than 170°
1. Destination
2. Starboard destination layline
3. Port vessel layline
4. Port destination layline
5. Starboard vessel layline
Laylines appear differently depending on destination
point and vessel position in relation to the wind.
When the destination point is upwind the layline
parallelogram is displayed as shown above. Once
your vessel has passed the destination point
(and you are ready to tack) only 2 sides of the
parallelogram will be shown. If the destination
point is downwind then only the vessel laylines are
displayed in the same color, this indicates the best
angle to sail.
Laylines types
There are 3 types of laylines:
• Mirrored TWA (True Wind Angle) — the vectors
use current TWA data to create laylines to an
upwind destination point, these are mirrored on
the opposite side of the wind. This option shows
the current course on the opposite tack.
• Fixed Angles — the vectors are created based
on specied Upwind and Downwind angles.
These angles are set by default to 45° and 165°
respectively and can be congured in the menu.
• Polars — the vectors use an imported polar table
for your vessel to create the laylines.
Laylines - Leeway calculations
The Laylines features uses calculations based on
the selected boat type to work out leeway.
Boat Type < 5 knots 5 to 18 knots > 18 knots
Race Sail 3° up to 5° 5°
Sail Cruiser 3° 5° to 10° 5°
Catamaran 3° 10° to 20° 5°
If your hull behaves differently than expected try
changing the Boat Type setting.
Enabling and disabling laylines
With the Boat Type setting set to either, Sail
Cruiser, Race Sail or Catamaran Laylines can be
enabled and disabled.
From the Chart application menu:
1. Select Presentation.
2. Select Vectors.
3. Select Laylines so that On is highlighted to
enable laylines, or
4. Select Laylines so that Off is highlighted to
disable laylines.
Changing layline type
From the Chart application’s Vectors menu:
1. Select Laylines Set-up.
2. Select Laylines Type.
3. Select the type of Laylines you want to use.
The Polars option is only enabled when a Polar
table has been imported.
Adjusting laylines for tidal ow
An option is available to automatically adjust the
laylines to take into account tidal ow.
From the Laylines Set-up menu:
1. Select Adjust for Tides so that On is highlighted.
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