The ships North up (SNU) displays above show the sequence of events as when your own vessel alters course in relative motion unstabilised displays
NORTH UP DISPLAY:
- Picture doesn’t smudge in azimuth and bearings can be taken accurately.
- Plotting is quite accurate even during heavy yaws.
- All bearings are true.
- Chart and PPI . Being north up it is easier to relate.
- There is no disorientation due to alteration of course.
- Heading marker indicates the gyro course steered at all times.
The ships head up (SHU) displays above show the sequence of events as when your own vessel alters course in relative motion unstabilised displays
HEADS UP DISPLAY:
- Picture smudges in azimuth during alteration of course.
- Because of smudging accurate bearings cannot be taken at that time.
- Plotting tends to be highly inaccurate during severe yaws.
- All bearings are relative.
- Radar picture is head up while chart is north up.
- After large alterations of course the observer tends to get dis- oriented with plotting as all targets have shifted.
- No indication on the screen of gyro course steered temporary wanderings may go undetected.