About
qtVlm is a full-featured sailing navigation and weather routing software developed by Meltemus SAS. Designed for both recreational and competitive sailors, it supports a wide range of chart formats including vectorial charts (S57 and S63), raster charts (KAP, GeoTIFF), Visit My Harbour charts, and MBTiles. The application's GRIB reader accepts most popular weather data formats and sources, allowing simultaneous loading of multiple GRIB files for side-by-side model comparison using wind, current, and wave parameters. The weather routing module is a core strength, offering multi-routing to identify optimal departure windows, route-following routing, and mixed sail/motor passage planning. Polar performance can be fine-tuned per conditions — including night-time efficiency adjustments and tack/gybe maneuver timing — ensuring accurate routing predictions. An integrated AIS module supports both NMEA hardware and internet-based target acquisition, while the Instruments module interfaces with NMEA data sources or an internal GPS to display and broadcast performance metrics such as VMG and target speed. A dedicated start-line module assists racing sailors with a countdown timer, distance and duration calculations, and a safety-zone display. qtVlm also features a Simulation Mode, letting users practice navigation using live GRIB wind and current data. It is Iridium GO! certified and integrates with Great Circle (Squid) GRIB subscriptions. A companion Android and Android Wear app (qtVlm Companion) enables interaction with the main application from on-deck devices. Free on all major desktop platforms; mobile versions (iOS, Android, Windows tablet) can be unlocked via in-app purchase.
Key Features
- Advanced Weather Routing: Multi-routing engine calculates optimal routes and departure windows using wind, current, and wave GRIB data, with fine-tuned polar performance settings.
- Multi-Format GRIB Reader: Load and compare multiple GRIB files simultaneously from most sources and formats, including support for Great Circle (Squid) subscriptions and Iridium GO! connectivity.
- Comprehensive Chart Support: Display vectorial charts (S57, S63), raster charts (KAP, GeoTIFF), MBTiles, and Visit My Harbour charts on a single unified interface.
- AIS & Instruments Module: Track AIS targets via NMEA hardware or internet feeds, and connect to NMEA instrument sources or an internal GPS to broadcast performance data like VMG and target speed.
- Racing Start-Line Assistant: Dedicated start-line module provides a countdown timer, distance and duration calculations, and a safety-zone display to help sailors nail race starts.
Use Cases
- Planning and optimizing offshore sailing passages using GRIB weather routing with wind, current, and wave data
- Comparing multiple weather models side-by-side to select the best departure window for a long-distance voyage
- Racing start-line management with countdown timers, distance calculations, and safety-zone overlays
- Monitoring vessel traffic and avoiding collisions using integrated AIS target display from NMEA or internet sources
- Simulating a planned route in Simulation Mode to practice navigation skills using live GRIB data before departure
Pros
- Free on All Desktop Platforms: Fully functional at no cost on Windows, macOS, Linux, and Raspberry Pi — making professional-grade routing accessible to all sailors.
- Powerful Weather Routing Engine: Multi-routing with polar performance tuning, motor segments, and simultaneous multi-model GRIB comparison gives sailors detailed passage planning capabilities.
- Broad Hardware & Data Integration: Iridium GO! certified, supports NMEA instruments, AIS, and multiple chart formats, allowing seamless integration into existing onboard systems.
- Cross-Platform & Mobile Support: Available on iOS, Android, and Windows tablets (with paid unlock), plus a dedicated Android Wear companion app for on-deck use.
Cons
- Mobile Version Requires Paid Unlock: While the desktop version is free, iOS, Android, and Windows tablet users must make an in-app purchase to access the full feature set.
- Donation-Dependent Development: The project relies entirely on user contributions to fund support and development, which may affect long-term feature velocity or support responsiveness.
- Primarily French Documentation: Much of the in-app text, documentation, and community forum content originates in French, which may be a barrier for non-French-speaking sailors.
Frequently Asked Questions
Is qtVlm free to use?
Yes, qtVlm is completely free on Windows, macOS, Linux, and Raspberry Pi. Mobile versions (iOS, Android, Windows tablet) have a free tier that can be unlocked to a full version via an in-app purchase.
What chart formats does qtVlm support?
qtVlm supports vectorial charts (S57 and S63), raster charts (KAP, GeoTIFF), Visit My Harbour charts, and MBTiles format.
Can I use qtVlm for offshore passage planning?
Yes. The weather routing module uses GRIB wind, current, and wave data to calculate optimized routes, find departure windows, and simulate passages — making it well-suited for offshore planning.
Does qtVlm work with AIS?
Yes, qtVlm includes an AIS module that can receive targets from NMEA hardware sources or via the internet, and display them on the chart.
What is qtVlm Companion?
qtVlm Companion is a dedicated Android and Android Wear application designed to interact with the main qtVlm software, allowing sailors to monitor navigation data and instruments from a wrist-worn or handheld Android device while on deck.
