Furuno CI-35H - Manual (Page 20)

1-8
Tide differential calculations in water tracking mode
Tide speeds of layer A (C1) and layer B (C2) relative to near-surface layer (Vw) are calculated as
follows:
D1 = Vw - Vwa (Speed of layer A based on near-surface layer)
D2 = Vw - Vwb (Speed of layer B based on near-surface layer)
The tide differential (Dd) between layers A and layer B is;
Dd = D2 - D1
= (Vw - Vwb) - (Vw - Vwa)
= Vwa - Vwb
= 8 - 5
= 3 (kt)
or
Dd = D1 - D2
= (Vw - Vwa) - (Vw - Vwb)
= Vwa - Vwb
= 5 - 8
= -3 (kt)
If you compare the results of calculations on this page with the ones on preceding pages, you will
find the tide differential of two layers is identical irrespective of tracking mode.
Tide differential based on layer A
Speed of layer B viewed from
layer A
Tide differential based on layer B
Speed of layer A viewed from
layer B