Passing-Of-Turn Settings; Motion-Along-Straight-Line Settings - Transas NAVI-SAILOR 4100 ECDIS Installation Manual

Procedure of TCS Control Setup Algorithms

Passing-of-Turn Settings

1. PivotX. Average shift of the ship’s pivot point forward relative to the ship’s
geometric centre, in meters. If set incorrectly, the ship may tend to go inside (to
correct this, it is necessary to increase PivotX) or outside (reduce the PivotX)
relative to the set turn trajectory. PivotY is normally “0”.
2. TurnRelaxROTChange. Characteristic time of the ship ROT change in
milliseconds. The larger TurnRelaxROTChange corresponds to smaller ship
manoeuvrability relative to the present configuration, and the other way round.
Typical Parameters:
Ship Type
Parameter in milliseconds
3. ROTDriftKoeff Characteristic of the ship ROT change. The approximate value
can be calculated as a constant ship drift angle during the turn/ROT grad/min.
If set incorrectly, the ship always goes inside (to correct this, it is necessary to
increase value) or outside (reduce the value) relative to the set turn trajectory.
Typical Parameters:
Ship Type
Parameter (value)
Note: In the case of excessive value reduction which is not commensurate with
the actual manoeuvring characteristics, there may be the ship track oscillation.

Motion-Along-Straight-Line Settings

For Raytheon (Anshutz) NP 2025 (NP2025+) autopilot, this values are of no importance.
1. TimeOnLeg – Characteristic time of the ship’s HTS change in milliseconds.
The larger TimeOnLeg corresponds to a smaller ship manoeuvrability relative
to the ready configuration, and the other way round.
Typical Parameters:
Ship Type
Parameter in milliseconds
2. XTEs; XTE_Ks – values which determine width of ranges and their corresponding
course correction in the direction which will bring back to the route leg. The change
of values is required in the case of incorrect ship behaviour as it moves along the
straight line under constant environmental conditions (motion along a pronounced
sinusoid or motion at a large distance off the route leg). If the ship moves along
a sinusoid around the route leg, the course correction coefficient should be
decreased within the observed amplitude. If the ship’s mean position is off the route
leg, the coefficient is required to be increased, or a new band should be set. In any
case, it is advisable to leave a band with zero coefficient (deadband). The table
provides initial range value and their corresponding correction coefficients.
XTEs (Width of Range, nm)
0.000
0.01
0.0101
0.04
0.04001
0.10
0.10001
0.5
0.50001
112 NAVI-SAILOR 4000/4100 ECDIS (v. 2.00.009). Installation Guide
Fast Ferry Container Ship
5000 4000
Fast Ferry Container Ship
0.26 0.14
Fast Ferry Container Ship
12 000 50 000
XTE_Ks (Course correction, deg)
0.0
0.0
2.0
2.0
4.0
4.0
6.0
6.0
6.0
Tanker
8000
Tanker
0.115
Tanker
30000
Value (example)
Deadband
2 deg
4 deg
6 deg