Tacking should only be performed into the wind and must be tried out in calm sea
conditions with light wind to find out how it works on your boat. Due to a wide range of
boat characteristics (from cruising to racing boats) the performance of the tack function may
vary from boat to boat.
Tacking in WIND mode as compared to AUTO mode is performed when sailing with
apparent or true wind as the reference. The true wind angle should be less than 90 degrees.
The rate of turn during the tack will be given by the Tack time defined in the sailing
parameter setup. The tack time is also controlled by the speed of the boat to prevent loss of
speed during a tack.
You can initiate the tack function from WIND mode.
When you initiate the tacking, the autopilot immediately mirrors the set wind angle to the
opposite side of the bow.
You can interrupt the tack operation as long as the tack dialog is open by selecting the
opposite tacking direction. When interrupted, the boat returns to the previous set heading.
Gybing
Gybing is possible when the true wind angle is larger than 120°.
The time to make a gybe is determined by the speed of the boat to make it as quick as
possible within control.
Tack and gybe prevent
You should use the autopilot with care when beating and running.
If the sails are unbalanced when beating, yaw forces from the sails can drive the boat into the
wind. If the boat is driven beyond the set minimum wind angle, the thrust from the sails
suddenly disappears and reduces the boat speed. The boat becomes more difficult to steer
as the rudder becomes less effective.
The tack prevent function in WIND mode has been implemented to avoid such situations. It
reacts immediately when the apparent wind angle becomes 5° less than the set minimum
wind angle, and more rudder is commanded.
When running, it is difficult to steer the boat with waves coming sideways or from behind.
The waves can yaw the boat into an unwanted gybe; this can be hazardous for both the crew
and the mast.
The gybe prevent function is activated when the actual apparent wind angle becomes
greater than 175° or gets opposite to the set wind angle. More rudder is commanded to
prevent an unwanted gybe.
The tack and gybe prevent functions are not a guarantee against getting into a hazardous
situation. If the effect of the rudder and/or drive unit is not adequate, a dangerous situation
may occur. Pay particular attention in such situations.
WIND Nav mode
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Note: The WIND Nav mode is only available if the system has been set up for boat type
Sail. This mode is not available for NAC-1, NAC-2 or NAC-3 autopilot computers.
In WIND Nav mode the autopilot steers the boat given both wind and position data.
In this mode the autopilot calculates the initial course change needed to navigate towards
the active waypoint, but the pilot also utilizes the current wind direction in the calculation.
Turn pattern steering
The autopilot includes a number of automatic turn steering features when the autopilot is in
AUTO mode.
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Note: The turn steering option is not be available if the boat type is set to SAIL in the
Autopilot Commissioning dialog, instead the tack/gybe feature is implemented.
Initiating a turn
You start the turn by selecting the relevant turn icon, followed by selecting the port or
starboard options in the turn dialog to select the turn direction.
Autopilot | NSO evo2 Operator Manual
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