Station · estuary
Nethermill Reach
Floods in four hours and takes eight to go. Do not plan a passage on the mean.
48 hours · height in metres above chart datum · all eight constituents
- Mean spring range
- 6.28 m
- Mean neap range
- 3.12 m
- MHWS
- 7.69 m
- MLWS
- 1.41 m
- Form factor
- 0.06
- Classification
- semidiurnal
Estuary station. The flood is shorter than the ebb, which is M4 doing the same job in a different phase.
Nine miles inside the mouth, soft mud, drying banks either side of the channel.
M4 is 17.9% of M2 here. Above about a quarter, and in the right phase, that is enough to flatten the crest of the tide into two — over one spring–neap cycle of 14.765 days this station carries a second high water on twelve of its twenty-nine tides. The two days drawn above are deliberately at springs, which is when it is clearest — a page that quietly picked its best two days without saying so would be a brochure. In them there are 4 high waters .
The constituent table
| Id | Constituent | Period, h | Amplitude, m | Phase g |
|---|---|---|---|---|
| M2 | Principal lunar semidiurnal | 12.4206012 | 2.35 | 12° |
| S2 | Principal solar semidiurnal | 12.0000000 | 0.79 | 58° |
| N2 | Larger lunar elliptic semidiurnal | 12.6583475 | 0.45 | 354° |
| K2 | Lunisolar semidiurnal | 11.9672348 | 0.22 | 56° |
| K1 | Lunisolar diurnal | 23.9344697 | 0.10 | 168° |
| O1 | Principal lunar diurnal | 25.8193417 | 0.08 | 30° |
| P1 | Principal solar diurnal | 24.0658902 | 0.03 | 164° |
| M4 | Shallow water overtide of M2 | 6.2103006 | 0.42 | 96° |
High and low water, 48 hours
| Time | Event | Height, m |
|---|---|---|
| day 1 01:03 | High water | 8.36 |
| day 1 06:27 | Low water | 1.18 |
| day 1 13:21 | High water | 8.54 |
| day 1 18:49 | Low water | 0.85 |
| day 2 01:45 | High water | 8.53 |
| day 2 07:08 | Low water | 0.97 |
| day 2 14:03 | High water | 8.61 |
| day 2 19:30 | Low water | 0.65 |
Survey sheet NR/2
265 soundings on run lines 46 units apart, 37 of them drying heights, deepest 12.1 m. One stroke on the sheet — the coastline — and no depth contours. Why.
Wrackline is an aid to planning and is not a substitute for an official tide table. Do not navigate on it.