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S-104 is the S-100 product specification for water level information used in navigation.
It answers a simple but critical question — how high is the sea surface relative to chart datum along my route, right now and over the next few hours?
With S-104 water levels you can:
Refine under keel clearance (UKC) calculations in shallow or constrained waters
Plan more precise tidal windows for deep draught vessels
Improve safety margins in bar crossings, river entrances and port approaches
S-111 is the S-100 specification for surface currents — speed and direction at or near the surface.
For shipping, ports and pilots, this helps with:
Pilotage and manoeuvring — understanding cross set and drift in turns, channels and berths
Transit planning — using favourable currents, avoiding adverse ones
Risk management — identifying areas where eddies and shear zones may affect track keeping
Tidetech’s S-111-ready models provide gridded current fields that can be visualised directly in compatible navigation and decision support systems, alongside chart and AIS layers.
You cannot safely interpret dynamic water levels and currents without a good picture of the seabed.
S-102 is the S-100 product specification for high resolution bathymetric surfaces. It effectively replaces a single chart sounding with a detailed depth grid.
For Tidetech, S-102-quality bathymetry is the foundation that allows us to:
Resolve channels, shoals, banks and harbour basins accurately
Simulate how tides and currents accelerate, slow or diverge over these features
Support more reliable S-104 and S-111 outputs, particularly in shallow, coastal and port environments where accurate depth relative to chart datum is critical
In short, S-102 underpins the quality and usefulness of S-104 and S-111. However, Tidetech does not supply S-102 as an interoperable product — these are available from hydrographic offices or certified suppliers.
