Optional Functions; North Speed Error Correction - C.Plath NAVIGAT X MK 1 Mod. 10 Operator's Manual

NAVIGAT X MK 1 Mod. 10 / SR-180 MK 1 Mod. 10
2.3.8 Optional Functions (available if relevant equipment installed)
Ext. Alarm Acknowledge
Mutes the alarm buzzer from a remote facility (e.g. a central alarm panel). The alarm
message remains on the display screen until the alarm is confirmed.
Turn Heading Display 180°
Turns the heading display by 180° (e.g. for operation in ferries). Actuated by external
selector switch.
Analogue Rate of Turn Display Damping
Turns damping of the analogue rate of turn output on/off. Actuated by external selec-
tor switch.
Watch Alarm Trigger Output
Activates the watch alarm trigger relais for 100 msec. Actuated by pressing any key
on the control and display unit.
2.3.9

North Speed Error Correction

The NAVIGAT X Mk 1 gyrocompass system provides automatic correction of the
north speed error. If correction is active, the system permanently calculates the north
speed error from the current speed and position and corrects the gyrocompass head-
ing data accordingly.
The north speed error δ arises from the combination of the ship's speed with the
rotation of the earth. Depending upon the latitude and the vessel's speed and direc-
tion, the heading indicated by an uncorrected gyrocompass deviates from the true
heading by the north speed error δ.
As a reference, a set of error tables is provided at the back of this manual which give
the north speed error δ of an uncorrected gyrocompass at different headings, speeds
and latitudes.
Page 2-06
The mathematical formula for the north speed error δ is:
δ
sin = –
where: v = speed (kts.)
ϕ = latitude
904 = rotational speed of the earth (kts.)
( )
v · cos hdg.
904 · cos ϕ
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