Station · reference

Halberry Roads

The reference station. Everything on this site is checked against it first.

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

Mean spring range: 7.90 m
Mean neap range: 3.70 m
MHWS: 9.25 m
MLWS: 1.35 m
Form factor: 0.05
Classification: semidiurnal

Reference station. The predictor is checked here first because everything else is checked against it.

Open coast, hard bottom, no bar. A tide that behaves.

The constituent table

Amplitude and phase lag at Halberry Roads. 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	2.90	318°
S2	Principal solar semidiurnal	12.0000000	1.05	4°
N2	Larger lunar elliptic semidiurnal	12.6583475	0.56	300°
K2	Lunisolar semidiurnal	11.9672348	0.29	2°
K1	Lunisolar diurnal	23.9344697	0.11	122°
O1	Principal lunar diurnal	25.8193417	0.09	348°
P1	Principal solar diurnal	24.0658902	0.04	118°
M4	Shallow water overtide of M2	6.2103006	0.12	210°

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 05:12	Low water	0.90
day 1 11:07	High water	9.94
day 1 17:31	Low water	0.50
day 1 23:31	High water	10.05
day 2 05:50	Low water	0.72
day 2 11:46	High water	10.14
day 2 18:09	Low water	0.36

Survey sheet HR/1

175 soundings on run lines 58 units apart, 7 of them drying heights, deepest 23.6 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.