Section 5 Basic Operation of the Radar  5-20 
 
[TM]  True Motion Mode (True Motion display) 
• In Ground mode, the own ship’s display 
position moves according to the Speed 
Over the Ground (SOG) and fixed targets 
such as land are fixed on the radar screen. 
• In Water mode, the own ship’s display 
position moves according to the Speed 
Through Water (STW) and fixed targets 
such as land move according to the 
difference between the Speed Through 
Water (STW) and the Speed Over the 
Ground (SOG). 
• When the own ship reaches to the true 
motion status, the own ship’s position is set 
at the position of about 69% of the screen 
radius in direction opposite to the own ship’s 
course by adding the influence of the tidal 
current. The ship’s position starts to move 
according to the own ship’s speed, course, 
and influence of the tidal current. When the 
own ship’s position reaches the position of 
about 69% of the screen radius, the position 
is reset to the position of about 75% of the 
screen radius in the direction opposite to the 
own ship’s course (COG) by adding the 
influence of the tidal current at that time. 
 
 
[RM(T)] 
or 
[RM(R)] 
Relative Motion Mode (Relative Motion 
display) 
• Own ship is fixed at the centre of the radar 
screen and fixed targets such as land move 
 
• The own ship’s position is reset in [TM] (true 
motion display) mode. For the details, refer 
to "5.4.6.1 Resetting own ship to its initial 
position in [TM] (True Motion display) 
 
 
 
5.4.6.1  Resetting own ship to its initial position in [TM] 
(True Motion display) mode 
1  Select [TM Reset] from the Motion mode. 
Own ship is reset to its initial position as established when the relative motion mode is changed 
to the true motion mode. The ship starts moving from that position. 
   
Fixed on the 
radar display 
depending on 
own ship's 
speed