Operation Manual

34 |
Using the autopilot | NSS Operator Manual
Depth Contour Tracking, DCT
TM
If the system has input from an echosounder, the autopilot can be set to follow a depth
contour.
Warning: Do not use this feature unless the seabed is suitable. Do
not use it in rocky waters where the depth is varying signi cantly over a
small area.
Slope Narrow
channel
Ridge
Use the following process to initiate DCT steering;
1.
Ensure that you have depth reading on the NSS unit or on a separate depth instrument
2. Steer the boat to the depth you want to track, and in the direction of the depth contour (main course)
3. Activate AUTO mode, select DCT steering and monitor the depth reading
4. Use the port and starboard indicators in the autopilot pop-up to initiate the DCT steering to follow the
bottom sloping to starboard or to port
The following parameters are available for DCT steering:
Turn parameter Range Change per step Default
Depth gain 5 - 95 5 5
Contour Cross Angle 0° - 50° 1 0
Depth gain
This parameter determines the ratio between commanded rudder and the deviation from the
selected depth contour. The higher depth gain value the more rudder is applied.
If the value is too small it will take a long time to compensate for drifting off the set depth
contour, and the autopilot will fail to keep the boat on the selected depth.
If the value is set too high the overshoot will increase and the steering will be unstable.
Contour Cross Angle (CCA)
The CCA is an angle that is added to or subtracted from the set course.
With this parameter you can make the boat yaw around the reference depth with lazy-s
movements.
The larger the CCA the bigger yawing will be allowed. If you the CCA set to zero there is no
S-ing.