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GWeatherRouting vs qtVlm: catalog facts
GWeatherRouting	qtVlm
	Screenshots
Best for: Sailors planning coastal or offshore routes with weather forecasts	Best for: Cruising and racing sailors who plan routes around weather
Free Free and open source under GPL-3.0-or-later.	Free + paid options The GRIB viewer is free; mobile and tablet apps, chart packs and the GRIB service are paid.
Windows, Linux	Windows, Android, iOS
Plans routes using GRIB weather data and boat polar diagrams Imports and exports GPX points and tracks Supports chart formats including GeoJSON, KAP, and GeoTIFF Available for Linux and Windows	Weather routing with departure-time comparison Reads S57, S63, raster and MBTiles charts AIS and NMEA instrument support Iridium GO certified
The listed downloads are for Linux and Windows	Mobile versions and chart packs are paid Wide feature set takes time to learn
Downloadable app	Downloadable app
Open source	Not open source
License: GPL-3.0-or-later	License not stated
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Sources for GWeatherRouting gweatherrouting.org Catalog checked October 8, 2026	Official website Full listing and sources Sources for qtVlm meltemus.com apps.apple.com/us/app/qtvlm/id999110023 Catalog checked September 24, 2026

“Not stated” means we have not confirmed it. Features can vary by device and plan.

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