Comparison
NauticCalc vs online calculators
Many skippers use free web tools for variation, course or ETA. At sea, signal, readability and your vessel matter — not just the formula.
Web calculators at sea
In harbour with Wi‑Fi, simple websites often suffice. Below deck, with weak signal or on the open sea, you're missing a deviation table, logbook, GPS context and a seamless workflow from variation to course correction — and each calculator only handles part of the job.
Quick comparison
- ·Online calculators: often free, individual formulas (variation, ETA, conversions)
- ·Online calculators: usually need browser + signal — no consistent offline use
- ·Online calculators: no vessel-specific deviation table, no local logbook
- ·NauticCalc: course chain rwK/mwK/MgK, tidal set, variation (WMM2025) — offline on iPhone
- ·NauticCalc: logbook and export local — data stays on device
- ·NauticCalc: one-time purchase, no subscription for core calculators — web tools often ad-funded
Comparison table
| marketingPages.common.comparisonFeatureColumn | marketingPages.common.comparisonNauticcalcColumn | Online calculators |
|---|---|---|
| Offline calculators (course, variation, ETA) | Yes, without network | Mostly signal-dependent only |
| Logbook & export | Local on iPhone | Rare / none |
| Subscription | One-time purchase, no subscription | Free, often with ads |
| Account | No login for core features | Usually none, sometimes tracking |
| Variation (WMM) | WMM2025, offline | Individual calculators, inconsistent |
| Course correction & tidal set | rwK/mwK/MgK, tidal triangle | Often partial features only |
| Charts / routing | No (calculator aid) | No |
| Deviation table | Vessel-specific, local | Practically never |
Offline on the bridge
NauticCalc core calculators and logbook run without network. Web calculators are handy for planning at home — at sea you often still need a local solution.
Fair comparison
Online calculators make sense for quick single calculations in harbour. NauticCalc is not a replacement for every website — but the tool when you want to work offline, vessel-specific and with a logbook.
Frequently asked questions
Not across the board. For a single variation in harbour, a website often suffices. NauticCalc bundles course, tidal set, variation, ETA and logbook offline — especially when you need to calculate or document without signal.
Web tools rarely store vessel-specific deviation permanently and privately on device. NauticCalc keeps your table locally for the course chain.
Not for core calculators and logbook. Live weather and WorldTides tides are optional with your own API key (BYOK).
No — they serve a different purpose. Weakness is usually no offline use, no integrated logbook and no seamless nautical workflow.
Related topics
Test offline on the bridge
App Store · May 2026
