Station · control

Marnhead Test Gauge

One constituent and nothing else. A tide that could not happen, kept so the predictor can be checked against arithmetic.

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

Mean spring range: 3.00 m
Mean neap range: 3.00 m
MHWS: 3.10 m
MLWS: 0.10 m
Form factor: 0.00
Classification: semidiurnal

Control station. One constituent and nothing else — a tide that could not happen, kept so a bad build shows up here first.

Not a place. A synthetic station carried in the same table as the real ones so that a bad build shows up here first.

One constituent at 1.50 m and seven at zero, so the curve above is a pure cosine of period 12.4206012 h and amplitude 1.50 m about 1.60 m. Every high water is the same height as every other one and there are no springs and no neaps, because springs and neaps are S2 beating against M2 and there is no S2 here. If this page ever stops being a clean sine, the predictor is wrong and nothing else on the site can be trusted.

The constituent table

Amplitude and phase lag at Marnhead Test Gauge. 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	1.50	0°
S2	Principal solar semidiurnal	12.0000000	0.00	0°
N2	Larger lunar elliptic semidiurnal	12.6583475	0.00	0°
K2	Lunisolar semidiurnal	11.9672348	0.00	0°
K1	Lunisolar diurnal	23.9344697	0.00	0°
O1	Principal lunar diurnal	25.8193417	0.00	0°
P1	Principal solar diurnal	24.0658902	0.00	0°
M4	Shallow water overtide of M2	6.2103006	0.00	0°

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 06:13	Low water	0.10
day 1 12:25	High water	3.10
day 1 18:38	Low water	0.10
day 2 00:50	High water	3.10
day 2 07:03	Low water	0.10
day 2 13:16	High water	3.10
day 2 19:29	Low water	0.10

Survey sheet

There is none. Marnhead Test Gauge is not a place, so there is nothing to survey, and a sheet drawn for it would be the only invented thing on the wall. The other seven sheets.

Get Wrackline

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