Station · degenerate

Feltwater Ness

Half a metre on a spring. The semidiurnal wave has a node not far offshore.

48 hours · height in metres above chart datum · all eight constituents

Mean spring range: 0.74 m
Mean neap range: 0.38 m
MHWS: 1.12 m
MLWS: 0.38 m
Form factor: 0.35
Classification: mixed, mainly semidiurnal

Degenerate station. Near a node in the semidiurnal wave, so the range is small and the weather is most of it.

Shoal ground on the edge of an amphidrome. The tide here is mostly wind.

The constituent table

Amplitude and phase lag at Feltwater Ness. The periods are astronomy and are the same everywhere; the two right-hand columns are the whole of what a tidal analysis produces.
Id	Constituent	Period, h	Amplitude, m	Phase g
M2	Principal lunar semidiurnal	12.4206012	0.28	208°
S2	Principal solar semidiurnal	12.0000000	0.09	250°
N2	Larger lunar elliptic semidiurnal	12.6583475	0.05	190°
K2	Lunisolar semidiurnal	11.9672348	0.03	248°
K1	Lunisolar diurnal	23.9344697	0.07	20°
O1	Principal lunar diurnal	25.8193417	0.06	260°
P1	Principal solar diurnal	24.0658902	0.02	16°
M4	Shallow water overtide of M2	6.2103006	0.02	60°

High and low water, 48 hours

Turning points of the curve above, read off the same series that draws it.
Time	Event	Height, m
day 1 01:29	Low water	0.41
day 1 07:16	High water	1.14
day 1 13:28	Low water	0.26
day 1 19:53	High water	1.28
day 2 02:09	Low water	0.40
day 2 07:56	High water	1.14
day 2 14:03	Low water	0.23
day 2 20:35	High water	1.31

Survey sheet FN/1

166 soundings on run lines 60 units apart, 31 of them drying heights, deepest 8.0 m. One stroke on the sheet — the coastline — and no depth contours. Why.

Get Wrackline

Wrackline is an aid to planning and is not a substitute for an official tide table. Do not navigate on it.