Guides
🌊 Tide model
How Kielwasser computes tides itself — model, datum, accuracy and limits. Including disclaimer.
🌊 What is Kielwasser Tides?
Kielwasser Tides is our own modelled tide model. It provides high and low water plus the water-level curve near coasts worldwide — even where no official gauge is in range. The datum is LAT (lowest astronomical tide, equal to chart datum). Where an official prediction (e.g. BSH, Rijkswaterstaat) is in range, that takes precedence; Kielwasser Tides fills the gaps.
⚙️ How it works
It is based on the harmonic tidal constituents from the global ocean model FES2022. From the amplitude and phase of the main partial tides (M2, S2, K1, O1 and others) the model synthesises the tide curve for any position, including astronomical nodal corrections. A confidence gate hides positions where the model is not reliable (far inland, deep open basins).
📏 Accuracy and limits
The model works best on open coasts and in tidal areas. In low-tide waters (e.g. the Baltic) the values are small and driven more by wind and air pressure. In estuaries and far upriver (e.g. Hamburg, London) and in inland waters the model deliberately returns nothing. Storm surge, air pressure and local effects are not included.
⚠️ Disclaimer
Kielwasser Tides are modelled values without warranty and do not replace an official tide prediction. Do not use for navigation — always use the official tide tables and charts for your area when planning.
📊 Data basis: FES2022 (AVISO/CNES/LEGOS).