The app ecosystem for sailors has matured considerably. There are now serious, purpose-built tools for every stage of a passage — from pre-departure chart downloads to offshore GRIB email delivery via SSB radio. These guides cover how each category of tool works, where it fits in a typical setup, and what its real limitations are.
Sailing Navigation Apps: Navionics, iNavX, OpenCPN, and More
The practical guide to chart-plotting apps — which one belongs on your phone or tablet, how to download charts before you lose cell service, and where each tool falls short.
- Navionics: most-used coastal app
- iNavX + NOAA RNC for offshore
- OpenCPN: free and plugin-rich
Weather Apps for Sailors: PredictWind, Windy, and GRIB Tools
From the offshore gold standard to the free GRIB viewer you can use from any browser — what each weather app actually tells you, and what it leaves out.
- PredictWind: 4-model offshore routing
- Saildocs GRIB via email offshore
- Free vs paid: when it matters
Anchor Alarm Apps: How They Work and Why They Fail
Phone-based anchor alarms, chartplotter anchor watch, and OpenCPN — understanding GPS accuracy limits, false alarm causes, and what redundancy actually looks like.
- Anchor! app: simplest iOS/Android
- GPS accuracy: ±5m typical
- Redundancy beats single-system trust
SSB Radio Apps: Winlink, Airmail, and Sailmail Offshore
How offshore sailors use SSB/HF radio with Winlink and Sailmail to send email, download weather GRIBs, and file position reports — with no per-message cost beyond the hardware.
- Winlink email over HF radio
- Sailmail: $250/year flat rate
- Pactor modem: the required hardware
About These Guides
App pricing, subscription models, and feature sets change. Always verify current costs and availability on each developer's site. Offshore communications regulations vary by flag state and region — confirm licensing requirements for SSB and Winlink with the relevant authority before departure. See the navigation section for celestial and traditional piloting guides.