Furuno CI-80 - Manual (Page 9)

5
Speed of layer A based on ground (C1) can be calculated as
follows:
C1 = Vg – Vwa
= 10 – 7
= 3 (kt)
Nav-Tide
(Absolute tide)
Absolute tide can be measured in the nav-aided mode.
Nav-aided ship’s speed (Vn) is equivalent to ship’s ground
tracking speed in the ideal conditions. That is, the nav-tide can
be calculated by simply replacing Vg with Vn in the above
equation.
Tide Differential
Tide differential is a relative movement of tides at different
depths.
It can be measured in the ground tracking, water tracking and
nav-aided modes.
:Base of measurement
Layer A
Start of
trip End of
trip
(Moving)
10 NM (1 hour trip)
Layer B
(Moving)
2 kt
5 kt
2
3
Figure 7