Prerequisites
- NauticCalc on the iPhone (iOS 17.6+)
- One-time purchase completed — the core calculators work offline
- For live data: your own API keys (BYOK), best set up at the berth
Step 1: Use the core calculators offline
Course correction, variation, ETA and conversions work without a network — right on the device. That is the core for being underway.
Step 2: Prepare offline tides
Use the offline tides (~1,000 stations) for your area. For worldwide live tides, set up the WorldTides key.
Step 3: Set up live data at the berth
While on Wi-Fi, store your weather API keys so underway you only refresh them. Offline-first means: calculate locally, live data only if you want it — not offline-only.
Step 4: Logbook and export stay local
Logbook, GPS and export run locally — no account, no cloud sync by us. Your data stays on board.
Common mistakes
- Noticing only at sea that API keys are missing — set them up at the berth
- Confusing offline tides with worldwide live tides
- Underestimating the battery — GPS and the display draw power, keep the iPhone charged
Read next: Offline navigation · Set up a WorldTides key