Furuno CI-80 - Manual (Page 6)

2
Fixed
GPS satellites
Nav-aided speed
(Pseudo ground tracking speed)
Water tracking speed
Ground tracking speed
Near-surface layer
:Base of measurement
Figure 2
Tide
Tide is movement of watermass at a particular depth.
To know absolute tide (speed on ground), the following two
data are required:
1 Ship’s speed and course based on ground
2 Ship’s speed and course based on measuring layer (A)
Absolute tide is, then, given as a difference of these two speed
vectors.
Absolute Tide = 1 – 2
Fixed
Layer (A)
:Base of
measurement
2
1
Figure 3