Raymarine LIGHTHOUSE 3, Advanced Operation Instructions

Page: 188 / 450

4. Port destination layline
5. Starboard vessel layline
When the destination point is downwind the laylines will be displayed as an orange parallelogram
formation, adjusted for gybing, as shown below:
Displaying wind shift data
As True Wind Direction (TWD) is constantly changing, the position of the laylines changes over time.
These changes are shown as lighter colored shaded triangles which represent the variation of
TWD over a specified time period.
• With TWD holding at the high end of its range of variation, the vessel can tack to starboard and
will lay the windward or leeward mark as it enters the shaded area. However, if TWD shifts back
towards the lower end of its range of variation, the vessel will fall short of the layline and may have
to perform extra tacks to reach the waypoint.
• With TWD holding at the low end of its range of variation, the vessel can tack to starboard and will
only lay the windward or leeward mark when it reaches the end of the shaded area. However,
if TWD shifts back towards the high end of its range of variation, the vessel will overstand the
windward or leeward mark and may need to travel farther to reach the waypoint.
• Depending on the situation, the normal course of action would be to tack when the vessel is
halfway through the shaded area. However this may not be the shortest or quickest route.
Wind shift data options are available from the Laylines settings page:
Chart app > Settings > Laylines
188