How To Install qtVlm Routing Software On A Rockit Server Device

Nov 21, 2025

If you’re running a Rockit Server onboard, qtVlm is a great way to add proper weather routing and navigation on top of your Rockit data stack.

qtVlm is a navigation and weather routing package designed for sailing boats. It works with GRIB weather files, boat polars and live NMEA data to calculate fast, “sailable” routes, and it runs very happily on Raspberry Pi. Rockit Server devices are built around a Raspberry Pi 4B, which means lower power consumption than Pi 5-based solutions – helpful when you’re counting every amp on a 12V system.

What you’ll need

  1. Rockit Server running Raspberry Pi OS (Bookworm, 64-bit) – based on Raspberry Pi 4B.
  2. Internet access over Wi-Fi so the Rockit Server can download qtVlm and GRIB files.
  3. The default `rockit` user, which already has sudo access when the Rockit server boots.
  4. RealVNC Viewer on your laptop/tablet/desktop.
  5. An Actisense W2K-1 (or W2K-2) NMEA 2000 → Wi-Fi gateway on your N2K backbone, to provide NMEA-0183 over Wi-Fi into qtVlm.

Step 1 — Connect to the Rockit desktop with RealVNC

On a standard Rockit image, RealVNC Server is already installed and enabled.

On your laptop / tablet:

  1. Install RealVNC Viewer (Windows, macOS, Linux, iOS, Android all work).
  2. In RealVNC Viewer, connect to either:
  • rockit.local
  • or the Rockit Server’s IP address (e.g. 192.168.1.50).
  1. Log in as:
  • User: rockit
  • Password: your Rockit user password.

You should now see the Rockit desktop as if you were sitting at the nav station.

VNC gives you a second, remote way to drive your Rockit Server from the saloon or your desk at home.

Step 2 — Update the system

From the Rockit desktop, open Terminal or LXTerminal and run:

sudo apt update

sudo apt full-upgrade -y

sudo reboot

Reconnect with RealVNC Viewer after the reboot, then open a terminal again.

This gets you onto the latest OS packages before you drop qtVlm on top.

Step 3 — Download the qtVlm Raspberry Pi build

The qtVlm developers provide pre-built Raspberry Pi archives on their site.

In the browser inside your VNC session:

  1. Go to the qtVlm download page and then to the Raspberry Pi / Linux section.
  2. Choose the build that matches your Rockit OS; Raspberry Pi 4B + Bookworm, 64-bit.
  3. Download the .tar.gz archive into your Downloads folder (default).

You now have a compressed archive containing qtVlm and its support files.

Step 4 — Install qtVlm into your home folder

Back in Terminal:

cd ~/Downloads

ls

You should see something like:

qtVlm-5.12.xx--p1-64b-bookworm-rpi4.tar.gz

(Your version string may differ.)

Create a folder and extract qtVlm into it:

mkdir -p ~/qtVlm

tar -xvzf qtVlm-5.12.xx--p1-64b-bookworm-rpi4.tar.gz -C ~/qtVlm

Adjust the filename to match whatever you downloaded.

qtVlm on Linux is a “unpack and run” application: no fancy installer.

Test it:

cd ~/qtVlm

./qtVlm

qtVlm should start and open its main window on your VNC desktop (and/or Rockit touchscreen if you’re at the boat).

If it complains about a missing library, install the required package with;

 sudo apt install …

And try again.

Step 5 — Add a simple launcher script (optional, but convenient)

Create a tiny wrapper script so you don’t have to cd around each time:

nano ~/qtVlm/qtvlm.sh

Paste:

#!/bin/bash

cd /home/rockit/qtVlm

./qtVlm

Save and exit (Ctrl+O, Enter, Ctrl+X), then:

chmod +x ~/qtVlm/qtvlm.sh

You can now run:

~/qtVlm/qtvlm.sh

or wire that script up to a panel launcher or menu entry if you want it to behave like a normal app.

Step 6 — What qtVlm actually does (and why Rockit cares)

Before we wire it to the boat, a quick overview.

qtVlm is:

  • A navigation package for sailing boats (supports vector/raster charts including S57/S63 and VisitMyHarbour chart sets).
  • A full GRIB viewer – you can load multiple GRIB models (wind, current, waves) and inspect them on the chart.
  • A weather routing engine – it combines GRIBs with your boat’s polars to calculate optimum routes, including multi-routing for different departure times and constraints (min wind, max sea state, avoidance zones, etc.).
  • Fully NMEA-aware – it can take GPS, wind, depth, AIS and other NMEA-0183 data over TCP/UDP and drive live instruments and alarms.

For Rockit users that means:

  • You can plan and optimise passages on the same low-amp Rockit Server that’s logging your performance data.
  • You get a routing view that understands polars, wind and current, not just straight-line great-circle legs.
  • You can feed the polars that you generate in Rockit into qtVlm.
  • You can use qtVlm on the Rockit touchscreen at the nav station, while also mirroring it via VNC to a cockpit tablet.

Step 7 — Connect qtVlm to live boat data (via Actisense W2K over Wi-Fi)

The important bit:

  • qtVlm only understands NMEA-0183, not NMEA 2000.
  • Your boat is almost certainly running NMEA 2000 on the backbone.

So you need something that:

  1. Listens on the NMEA 2000 backbone, and
  2. Converts to NMEA-0183 and streams that over the network.

The neatest way to do this on a Rockit-equipped boat is an Actisense W2K-1 (or W2K-2):

  • It sits on the N2K backbone.
  • It converts NMEA 2000 PGNs into NMEA-0183 sentences.
  • It streams them over Wi-Fi using TCP and/or UDP, with up to three separate data servers.
  • Wire the Actisense W2K into your network

On the boat:

  1. Install the W2K on your NMEA 2000 backbone.
  • Configure the W2K (via its web interface) to:
  • Enable NMEA-0183 output over Wi-Fi.
  1. Choose TCP (easiest for a single Rockit client) and set:
  • Server IP: the W2K’s own IP (e.g. 192.168.4.1 if it’s the access point, or a DHCP address if it’s joined to a router).
  • Port: follow the Actisense instructions to configure the port.

  1. Make sure your Rockit Server joins the same Wi-Fi network:
  • If the W2K is acting as its own access point, connect the Rockit Server to that SSID.
  • If the W2K is a client of your onboard router, connect both Rockit Server and your tablet/laptop to that router’s Wi-Fi.

The W2K is now taking N2K data (position, wind, AIS, depth, etc.) and making it available as NMEA-0183 over Wi-Fi, exactly what qtVlm wants.

Add the NMEA connection in qtVlm

On the Rockit desktop (via VNC or touchscreen):

Start qtVlm (~/qtVlm/qtvlm.sh).
Go to Configuration → NMEA connections.
Add a Network / TCP connection:
Server / Host: the Actisense W2K IP (e.g. 192.168.4.1 or 192.168.1.20).
Port: whatever you configured on the W2K (e.g. 2000).
Tick Input and enable the connection.

If everything is wired correctly, you should see:

Position moving on the chart.
Speed/course, wind, depth etc. lighting up in qtVlm’s instrument windows.

If you’re already using a W2K for other apps (e.g. iPad nav apps), Rockit + qtVlm simply becomes another Wi-Fi client listening to the same NMEA-0183 stream.

Step 8 — Basic weather routing workflow on Rockit

Once live data is flowing:

  1. Load charts into qtVlm (e.g. VisitMyHarbour chart packs for qtVlm on Raspberry Pi, or S57/S63 sets if licensed).
  2. Import your boat’s polars:  qtVlm can use supplied polars or you can bring in your own Rockit-derived polars if/when you generate them.
  3. Grab GRIBs: Download GRIB files in the Rockit browser (Saildocs, PredictWind export, VMH, etc.) into a folder like ~/GRIB.  In qtVlm, open the GRIB viewer and load the files.
  4. Create a route / pathway:  Drop Points Of Interest (POIs) at start and destination.
  5. Run a routing using your GRIBs and polar file.
  6. Review the suggested path, ETAs and sail changes, adjust constraints, and re-run if needed.

All of that is running on the Rockit Server; you’re just interacting with it via touchscreen in the nav station and RealVNC anywhere else on the boat (or at home).

Step 9 — qtVlm on a Rockit touchscreen & over VNC

qtVlm is very usable on a touchscreen:

  • The toolbar icons are reasonably large; you can enlarge them and increase fonts in Configuration → General / Display to make things finger-friendly.
  • Panning/zooming charts works well using drag and on-screen buttons; gestures are handled at OS level if your display supports them.
  • Popup instruments (wind, speed, depth, AIS list) sit nicely beside the chart on a wide screen.

For VNC usage:

  • In RealVNC Viewer, drop colour depth to 16-bit and enable adaptive quality for better performance over Wi-Fi.
  • You can leave qtVlm running on the Rockit desktop and just reconnect from:
  • Cockpit tablet,
  • Saloon laptop,
  • Home office PC for passage planning before you leave.

Because the Rockit Server is Pi 4B based with relatively low idle and loaded power draw, you can comfortably leave it on as part of your always-on electronics cluster without blowing the amp-hour budget.

That’s it

You now have qtVlm navigation and weather routing running directly on a Rockit Server, fed with live NMEA-0183 data from an Actisense W2K over Wi-Fi, and controllable from:

A Rockit-connected touchscreen at the nav station, and
Any laptop/tablet with RealVNC Viewer.

You can find out more about qtVlm here;  qtVlm Home Page

You can find out about the Rockit Server Model 1 and 2 here.

Rockit Server Model 1

Rockit Server Model 2