Tidal Router — data sources & disclaimer

A free, browser-based pre-departure planning tool for the Netherlands + Germany Wadden Sea.

⚠️ Disclaimer — read before using

This tool is for passage planning only. It is not a navigational aid and must never be used as the sole or primary means of navigation.

All data shown (current, water level, tide timing, and especially charted depth) is derived from third-party sources listed below, on the schedule described below. It may be stale, incomplete, or wrong — see "Known limitations" for specific, disclosed gaps.
Always cross-check against official, up-to-date nautical charts, Notices to Mariners, tide tables, and pilotage guidance from your national hydrographic authority before and during any passage. This tool does not replace them and is not corrected against real-time Notices to Mariners.
The Wadden Sea's channels and sandbanks shift over time (storms, dredging, natural drift). A channel shown as safe here may no longer be safe, and a channel shown as shallow/blocked may since have been dredged or changed.
This is a hobby project, not a certified or professionally audited navigation product. It has no affiliation with, and is not endorsed by, RWS, BSH, BAW, or any hydrographic office.
No warranty of any kind is given or implied — not of accuracy, completeness, fitness for a particular purpose, or availability. The author(s) accept no liability whatsoever for any loss, damage, injury, grounding, delay, or other consequence arising from use of this tool, its data, or its output, to the fullest extent permitted by law.
Use entirely at your own risk. You, the skipper, remain solely responsible for the safe navigation of your vessel at all times.

Data sources, and what they don't cover

Data	Source	Coverage / notes
Tidal current + water level	TrilaWatt Hydrodynamik (BAW/mFUND, CC-BY 4.0)	A 2022 model run, not a live forecast — one representative year's tidal cycle, keyed by tidal phase. Won't reflect unusual wind-driven surge/set or any change since 2022.
Charted depth (Netherlands)	RWS official ENC (SOUNDG/DEPARE) via vaarweginformatie.nl	Real official chart data, RWS-corrected roughly weekly via Notices to Mariners upstream — but this app's own copy is a periodic snapshot, not live. ~72% of the Dutch domain has official coverage; the remaining ~28% (mostly open sea north of the barrier islands) falls back to the older TrilaWatt model bathymetry.
Charted depth (Germany)	BSH public WMS data, via the quantenschaum/mapping community mirror (GeoNutzV license)	Sparser sounding density than the Dutch side; refreshed on that project's own irregular schedule, not RWS's weekly cadence.
Chart tiles (visual basemap)	freenauticalchart.net (CC0, BSH/RWS-derived)	Visual reference only — explicitly not for navigation per its own license terms, same as this whole tool.
Tide predictions, Netherlands (HW/LW timing)	RWS waterinfo.rws.nl astronomical API	Real per-station predictions, Harlingen used as this app's own reference clock.
Tide predictions, Germany (HW/LW timing)	gezeiten.bsh.de	Real predictions for 5 German stations (Borkum, Norderney, Wilhelmshaven, Cuxhaven, List auf Sylt).
Measured water level, Netherlands	RWS waterinfo.rws.nl	Fetched live on every page load.
Measured water level, Germany	PEGELONLINE (WSV)	Fetched live on every page load, directly from the browser.

Known limitations

Germany's departure-time optimizer borrows the Netherlands' (Harlingen) real-calendar tidal reference clock, not its own. The underlying current/depth data for German routes is genuine BSH/TrilaWatt data, but the moment in the tidal cycle it's evaluated against may not exactly match Germany's own true tidal state at that instant.
Routes crossing the Netherlands/Germany border are not blended — there is a visible seam where the two countries' independent models meet.
German harbour timing offsets are not yet researched (Netherlands' stations have real, sourced HW-timing corrections relative to the reference station; Germany's do not yet).
This is a planning tool, not a live forecast for current/water level magnitude — see the TrilaWatt row above.
Depth values are smoothed/composited from multiple official and model sources with different resolutions and vintages; a single very recent, very local change (e.g. a storm reshaping a channel overnight) will not be reflected until the underlying data is refreshed and this app's data is re-extracted.

How current is the data, right now?

Measured water level (both countries): Genuinely live, refetched on every page load.
Tide predictions (HW/LW timing): Real astronomical predictions. Netherlands: refreshed automatically every week (limited by a rolling ~16-day upstream window). Germany: refreshed manually, roughly once a year, since the upstream source publishes a full year+ at a time.
Charted depth: Refreshed occasionally, not on a fixed schedule — see each source's own upstream update cadence above.
Tidal current/water-level model: Tied to a single fixed model year (2022) and only re-extracted if the source project (TrilaWatt/BAW) publishes an actual new model version — a rare, announced event, not something re-running the extraction on the same source data would improve.