Two ways to get tide predictions
NauticCalc is offline-first — that applies to tides too, but not for every bay worldwide. Skippers should know the difference before they discover at sea that the North Sea is “missing”.
Offline tides in the app
- Technology: harmonic constants (XTide/NOAA,
harmonics-dwf-free) - Coverage: roughly 1,000 stations, focus USA and selected international harbours
- Advantage: no connection, no API cost, instant on the bridge
- Limit: not every European bay is covered
→ Reading tides: HW, LW · Tide calculator
Live tides with WorldTides (BYOK)
- Technology: WorldTides API with your own key in the iOS keychain
- Coverage: worldwide, including Mediterranean, North Sea, many harbours
- Advantage: coverage where offline stations are absent
- Limit: internet required; quota/cost with the provider
BYOK (Bring Your Own Key): NauticCalc does not sell a tide subscription — you use your WorldTides account.
Comparison at a glance
| Offline tides | Live (WorldTides) | |
|---|---|---|
| Network | No | Yes |
| NauticCalc cost | One-time purchase | No tide subscription |
| Third-party cost | — | Key/quota at WorldTides |
| Europe cruising | Partial | Good |
| USA/Pacific cruising | Strong | Good |
What stays offline regardless?
Course, variation, current, ETA, logbook, GPS — independent of the tide key. See Sailing without internet.
Common misconceptions
- “The app has offline tides everywhere” — false for many EU bays without a station
- “Live = always more accurate” — only if station and time zone are correct
- Offline table replaces official tide tables — for safety: use the official source
Summary
Offline tides are ideal where stations are built in. For worldwide or European cruising you add WorldTides with your own key — transparent, with no hidden subscription from NauticCalc.
Further reading: Set up WorldTides key · Tides · Offline hub