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Calculate variation — offline for skippers
Compass course and chart only align when variation (and deviation if applicable) are correct. NauticCalc provides magnetic variation from WMM2025 — no network, right on the bridge.
At sea, the right variation matters
Many offerings are online-bound, hidden in chart apps or generic. Below deck without signal, nobody should have to search long — or confuse variation with deviation.
What NauticCalc delivers
- ·Magnetic variation from World Magnetic Model 2025
- ·Calculation offline on device — no network needed for core calculators
- ·Clear east/west indication for the course chain rwK → mwK → MgK
- ·Readable display for day, night and spray on the bridge
- ·Aid — does not replace official charts or certified equipment
Offline on the bridge
Variation and course calculators run locally on iPhone. No account, no cloud for the calculation.
By skippers, for skippers
No subscription, no ads, no login. One-time purchase — all core calculators permanently on device. Data stays on your iPhone.
Frequently asked questions
No — the calculation runs offline on device. Live weather and online tides are separate and optional (BYOK).
The NOAA World Magnetic Model 2025 (WMM2025) — for magnetic variation worldwide.
Variation is the local difference between true and magnetic north. Deviation comes from the ship's compass — NauticCalc can store your own deviation table.
No. NauticCalc is an aid. For passages, official sources and your skipper's judgement still apply.
Related topics
Variation at hand — even without network
Buy once · No subscription · iOS 17.6+
