AIS Watchkeeper — Operator Manual

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1. Overview

AIS Watchkeeper turns QGIS into a live maritime traffic console. It listens to an AIS receiver — either a USB/serial dongle or a network (TCP) feed — decodes the vessel broadcasts, and plots every ship on the map in real time, with heading, speed vector, track trail and a name learned from the traffic itself.

On top of the live picture it gives you four watchkeeping tools:

• The Guardian — draw guard zones on the map and get an alarm when a vessel enters, sits inside, or leaves one; optionally only for vessels you care about (guard groups).
• Coverage mapping — a running map of where your receiver actually hears Class A and Class B traffic, so you know your blind spots.
• Vessels — a live nearby list with bearing, range and fairway binding, plus a register of every ship seen.
• Routes — vessels are matched to the official Dutch fairway network, so you can watch a fairway as a strip (inbound/outbound), see its bridges and locks, and get a ship's ETA to any of them. Where the bundled network doesn't reach — anywhere outside the Netherlands — you can draw your own custom routes and bind traffic to them too.

Everything runs inside QGIS as a dockable panel. There's no separate application and no cloud service — the feed comes straight off your receiver to your machine. (The one exception is the live bridge/lock lookup in Section 9, which is best-effort and optional.)

The panel at a glance. One dock, six tabs, in the order you'll normally use them:

1. AIS stream — pick your source, connect, watch the raw feed, set how vessels are drawn.
2. AIS Guardian — arm the alarms and manage guard groups.
3. Vessels — the nearby list, the full register and your own fleet.
4. Routes — a table of fairways with traffic on them; open one as a strip.
5. Event log — every alarm and coverage event, exportable to CSV.
6. History — browse the recorded voyage archive (when voyage history is switched on).

A ? button in the top-right corner of the panel opens this manual at any time.

2. Installation

AIS Watchkeeper installs like any QGIS plugin from a ZIP, and it carries its own dependencies — you do not need to pip-install anything. The AIS decoder (pyais) and the serial driver (pyserial) are bundled inside the plugin.

Requirements

• QGIS 3.22 or newer. The plugin is Qt6/QGIS 4 compatible, so it runs on both current and next-generation QGIS.
• An AIS source: a serial/USB AIS receiver, or access to a TCP AIS feed (host and port).

Steps

1. In QGIS, open Plugins → Manage and Install Plugins…
2. Choose Install from ZIP.
3. Browse to the AIS Watchkeeper ZIP and click Install Plugin.
4. Confirm any "install untrusted plugin" prompt — this is normal for a plugin that isn't on the official repository.

Once installed you'll see an AIS Watchkeeper button on the toolbar and an entry under Plugins → AIS Watchkeeper. Either one toggles the dock open and closed — a single click opens the panel, builds its map layers and leaves it ready for a source.

First-run notice. The first time you open AIS Watchkeeper in a QGIS session, a short usage notice appears. It states that the tool receives, portrays and stores AIS messages, and that you — the operator — are solely responsible for complying with the privacy legislation that applies where you use it. Click I do to accept and the panel opens; Decline (or closing the notice) keeps it closed, and no AIS data is received or handled until you accept. The notice appears once per session.

3. Getting around QGIS

AIS Watchkeeper lives inside QGIS, so a few native QGIS habits make everything else easier. If you're already comfortable in QGIS, skim this and skip ahead.

3.1 Showing the Layers panel

The Layers panel is the list down the side of QGIS that shows every map layer — the basemap, your live vessels (liveFeedAIS), guard zones (guardZones), coverage, route markers, and so on. You'll need it to turn layers on and off and to edit guard zones and markers.

If it isn't visible: View → Panels → Layers (tick the box). The same menu lists every other panel, including AIS Watchkeeper itself, so you can re-open the plugin from here if you ever close it.

While you're there, also make sure the editing buttons are available: View → Toolbars → Digitizing Toolbar. That's where the pencil and the Add Feature buttons live.

3.2 Floating the panel onto a second screen

In a watchkeeping setup you often want the map filling one monitor and the AIS Watchkeeper panel on another. The panel is a standard QGIS dock, so:

• To undock it: grab the panel's title bar (where it says AIS Watchkeeper) and drag it out of the QGIS window — it becomes a free-floating window you can drop on a second monitor and resize. A double-click on the title bar does the same in one move.
• To re-dock it: drag it back to the left or right edge of the QGIS window until a highlighted strip appears, then release. Double-clicking the title bar again also snaps it home.

When floated, the panel is a normal window with its own maximise and minimise buttons, so you can size it freely or throw it full-screen on the second monitor. And whichever way you use it — docked or floated — if the panel is taller than the space it has (a small laptop screen, or a short dock), it grows a vertical scrollbar so nothing is clipped: just scroll to reach the controls lower down.

The same trick works on the Layers panel — handy if you want the map, the layer list, and the plugin spread across two screens.

3.3 The native editing pattern (add a guard zone or a marker)

Three features — guard zones, route reference markers and custom routes — are things you draw on the map using QGIS's own editing tools. They all follow the same five-step pattern, so learn it once:

1. In the Layers panel, click the layer you want to draw on to select it (guardZones for a zone, Route reference markers for a marker, Custom routes for a route).
2. Click Toggle Editing — the pencil button on the Digitizing toolbar. The layer is now editable (a pencil appears beside it in the Layers panel).
3. Click the matching Add Feature button: Add Polygon Feature for a guard zone, Add Point Feature for a marker, Add Line Feature for a custom route.
4. Draw on the map:
   • Guard zone (polygon): left-click to drop each corner, then right-click to finish the shape.
   • Marker (point): a single left-click where you want it.
   • Custom route (line): left-click each vertex along the route, then right-click to finish the line. The direction you draw it matters — see Section 9.8.
5. Click Save Layer Edits (the floppy-disk button), then click the pencil again to Toggle Editing off.

What happens after you finish drawing:

• Guard zone → AIS Watchkeeper's own zone form opens automatically. Give the zone a name, choose whether it's armed, whether it alarms on entry and/or exit, and whether it watches all vessels or only chosen guard groups, then click OK. (Section 7 covers what those settings do. To change a zone later, select it on the map and reopen its form from the AIS Guardian tab.)
• Marker → QGIS's standard attribute form asks for a name (a buoy, a VTS sector boundary, a berth). Type it and click OK. The marker snaps to the nearest fairway automatically and appears on that route's strip as a teal diamond at the correct distance along the route (Section 9).
• Custom route → QGIS's attribute form asks for a name. Type it and click OK. The route becomes a fairway you can bind traffic to, listed in the Routes tab in blue (Section 9.8).

Markers and zones are saved to disk in your profile, so they survive QGIS restarts and plugin upgrades.

3.4 Moving, reshaping and deleting a feature

Once a guard zone or a marker is drawn, you can change or remove it — same tools for both layers. First select the layer in the Layers panel and Toggle Editing on, then:

• Move or reshape it: pick the Vertex Tool on the Digitizing toolbar. Hover over the feature and its vertices light up. Drag a vertex to move it; for a guard-zone polygon, double-click an edge to add a new corner, or click a vertex and press Delete to remove that corner. To slide a whole feature without reshaping it, use the Move Feature(s) tool instead.
• Delete it: with the Select Features tool, click the marker or zone on the map so it highlights, then press the Delete key (or the Delete Selected button on the toolbar). Deleting a guard zone stops it alarming; deleting a marker removes it from the route strip.

Either way, finish with Save Layer Edits and toggle editing off. Nothing is permanent until you save.

Tip — placing a route marker accurately. A marker binds to whichever fairway is nearest to where you drop it, so put it where there's no doubt. Zoom in until the thin fairway lines appear on the chart (around 1:12500 or closer), then drop the marker in the middle of the fairway, right on a routeline. That way it snaps to the route you intended, at the correct distance along it, and lands exactly where you expect on the strip. Drop it loosely between two parallel fairways and it may bind to the wrong one.

4. Connecting a source

This is the first real step: pointing AIS Watchkeeper at your receiver. Open the dock and go to the AIS stream tab — the leftmost one. At the top you choose between three kinds of source:

• USB / Serial — a physical AIS receiver plugged into your machine (or a serial-to-USB adapter).
• Network (TCP) — an AIS feed delivered over the network from another host: a base-station, an aggregator, a multiplexer, or a shore server.
• Internet — a free or open online AIS service, for trying the plugin out before you have a receiver of your own (see §4.7).

Pick the radio button that matches what you have. The panel below swaps to show the right fields.

4.1 A USB / serial receiver

1. Plug the receiver in.
2. Select USB / Serial.
3. Open the Port dropdown and pick your device. Each entry shows the port, a description and a hardware tag (e.g. the USB vendor/product), so you can tell a real AIS receiver from, say, a Bluetooth COM port. If you plugged in after opening the panel, click Refresh to re-scan.
4. Set Baud to 38400 — the AIS standard. (Some receivers present their data at 4800; if 38400 gives you nothing, try that.)
5. Click Connect.

If you're not sure which port or baud is right, don't guess — use Auto-detect (next).

A note on Bluetooth receivers. Most Bluetooth AIS receivers pair with your computer as a virtual serial port. Once they're paired at the operating-system level, they appear in the Port dropdown just like a plugged-in USB device, and you connect to them exactly as above — pick the port, set the baud, Connect.

The exception is receivers that talk over Bluetooth Low Energy (a GATT connection) instead of a serial profile. These never present as a serial port, so they won't appear in the dropdown and aren't supported by AIS Watchkeeper, which speaks only serial and TCP. If your Bluetooth receiver pairs fine but never shows up as a port, it's most likely one of these — contact the plugin developer for support.

4.2 Auto-detect — let the plugin find it

The Auto-detect button does the port-and-baud hunt for you. It listens on each serial port in turn, trying the AIS standard 38400 first and then 4800, 9600 and 115200. A port producing valid AIS sentences is the winner; a port spitting garbage is rejected within a second or so, so the scan is quick.

1. Make sure the receiver is plugged in.
2. Click Auto-detect.
3. Watch the status line — it reports each port it tries and what it found (how many valid sentences, how many were AIS, how many GPS).
4. When it finds an AIS feed it selects that port and baud and connects automatically. If it finishes without finding AIS, nothing is connected and you'll see the per-port findings in the log to help you diagnose (e.g. a port that's all GPS and no AIS).

This is the fastest way to get going with unfamiliar hardware.

4.3 A network (TCP) feed

1. Select Network (TCP).
2. Enter the Host (an IP address or hostname) and Port of the feed.
3. Click Connect.

The plugin connects straight to the TCP NMEA stream and starts decoding. It also tolerates feeds that wrap each sentence in a NMEA TAG block (the \…\ prefix many aggregators and multiplexers add) — those are stripped automatically before decoding, so a feed that used to show nothing now works.

4.4 Secured feeds and logins

Before it connects a TCP source, AIS Watchkeeper quietly probes the endpoint to see whether it's plain, encrypted, or expecting a login. A normal open feed just connects as above and you'll notice nothing. But if the endpoint looks secured — it offers TLS, or it greets you with a login prompt and sends no data until you authenticate — a login dialog opens, pre-filled from what the probe found:

• A TLS toggle (with an option to accept a self-signed certificate), set on if the server offered encryption.
• An authentication method: none, username + password, or token.
• A login line template with {user}, {pass} and {token} placeholders — because there's no single standard AIS login, the exact line your server expects is configurable here.

Fill in your credentials and connect. You can store them safely: the dialog uses QGIS's own encrypted credential store, so the secret is held in QGIS's master-password-protected database, decrypted only at the moment of connecting, and never written into the plugin's own files. The plugin remembers the non-secret bits per host (the TLS flags, the login template, which stored credential to use) so the next connect pre-fills — but the password itself stays in QGIS's vault.

4.5 Knowing you're connected

Once a source is live:

• The Connect button changes to Disconnect.
• The feed-live indicator lights green (you'll see it here and on the AIS Guardian tab).
• The status line shows a state word plus running counts — sentences per second on the line, how many validated, and how many were AIS — so you can confirm real traffic is flowing, not just noise.
• Vessels begin appearing on the map within a sentence or two, and the map pans once to your first contact.

The AIS stream tab, connected to the aisstream.io internet feed: the source panel, the Settings box (speed vector, symbol amplifier, trails, plot-vessels, own position and the toggles), the Voyage-history box, the live "msg/s" rate graph, and the decoded sentence log with running counts.

4.6 Pausing and disconnecting

• Disconnect stops the feed but leaves the plugin and your map layers in place.
• Full stop is the bigger hammer: it halts everything the plugin is doing — the feed, the auto-detect scan, every timer and layer update — so you can freeze the session cleanly (for example before unplugging hardware). The same button resumes. On Windows this is also the safe way to stop a serial receiver before pulling it out, avoiding the rare disconnect-mid-read crash.

4.7 Internet sources — trying it without a receiver

If you don't have a receiver yet and just want to see AIS Watchkeeper working, choose Internet. A dropdown offers a few free or open online AIS services:

• Norway — Kystverket — the Norwegian Coastal Administration's public feed. It needs no signup at all: pick it, click Connect, and you'll see live traffic along the Norwegian coast within seconds. Coverage is Norway only, but it's the fastest way to prove the plugin works.
• Global — aisstream.io — a free, worldwide service that streams the vessels in a box around your own position, so you see ships in your own waters. It needs a free API key: click Get key to open the sign-up page, paste the key into the API key field, and — because it's a location-based feed — set your own position on the map first (see §6). Then Connect.
• Global — VesselAPI — a second worldwide option, also free with a key (Get key opens its dashboard). It polls the vessels in the same own-position box every half-minute.

For the two global services the Area radius (nm) box sets how large a box around your position is requested. If you choose a location-based service without a position set, the plugin reminds you to set one first. Your key is stored safely in QGIS's settings, per service, so you paste it only once.

A word of perspective: these internet feeds are for testing, and for coverage where you have no receiver of your own. In your local waters a real antenna hears far more, far sooner. Among free worldwide feeds, aisstream.io and VesselAPI are the genuine options — most other "global" services are paid, or require you to run and share your own receiver.

Attribution. The Norway / Kystverket feed is open data under NLOD 2.0. If you use, store or share it you must credit the source: "Contains data under the Norwegian Licence for Open Government Data (NLOD) distributed by the Norwegian Coastal Administration (Kystverket)" (https://data.norge.no/nlod/en/2.0). The open feed already excludes small fishing (<15 m) and recreational (<45 m) craft, so those vessels are never received or stored. aisstream.io and VesselAPI are used under their own free-tier terms with your personal API key.

The Kystverket licence was reviewed for possible infringement and found to be in compliance: because the restricted small-craft data is excluded from the open feed it is never stored or redistributed, and NLOD 2.0 permits the plugin's storage, sharing and commercial use provided the attribution above is given. This finding is also shown in the app when you select the Kystverket source.

5. Reading the map

Once a source is live, decoded vessels are written to a map layer called liveFeedAIS and updated continuously. Everything in this section is about that live picture — what the symbols mean and how to tune them. All the tuning controls live in the Settings box on the AIS stream tab, and your choices are saved with the QGIS project, so they come back next time you open it.

5.1 Vessel symbols

Each vessel is drawn as a ship-shaped symbol coloured by type, scaled to the vessel's real length and beam (from its AIS dimensions) and rotated to point the way it's heading — true heading if the vessel reports it, otherwise course over ground. So a 300 m tanker looks like a 300 m tanker, pointing the right way; a small craft looks small. Where a vessel hasn't reported its dimensions yet, a sensible default size is used until it does.

The type comes from the vessel's AIS ship-and-cargo type code. The legend:

Symbol	Type	AIS code
	Cargo	70–79
	Tanker	80–89
	Passenger	60–69
	High-speed craft	40–49
	WIG (wing-in-ground)	20–29
	Fishing	30
	Towing	31, 32
	Dredger	33
	Diving ops	34
	Military	35, 59
	Sailing	36
	Pleasure craft	37
	Pilot	50
	SAR	51
	Tug	52, 53
	Anti-pollution	54
	Law enforcement	55
	Medical transport	58
	Other	90–99
	Other identified	remaining codes
▲ (triangle)	Unidentified — no type reported yet	none

A vessel shows as a small triangle until it broadcasts a type; once it does, it switches to the matching ship symbol. The triangle still rotates to the vessel's heading, so even unidentified contacts show which way they're pointing.

5.2 Speed vectors

A speed vector is a line projected ahead of each moving vessel showing where it will be in the next few minutes — the standard way to read who's going where at a glance. Two dropdowns in Settings control it:

• vectorlength — how far ahead to project: none, 1, 3 or 6 minutes. The line length scales with the vessel's speed, so faster ships draw longer vectors.
• vectorsource — which bearing the vector follows: COG (course over ground, drawn green) or heading (the way the bow points, drawn blue). The colour change makes it obvious which you're looking at — useful when a vessel is being set by current or wind and its heading and course differ.

Stopped vessels (zero speed) draw no vector.

5.3 Trails

trails draws a faint dotted line through each vessel's recent positions, so you can see where it has been. The dropdown sets how many past fixes to join: off, 5, 10 or 20. Longer trails give more history but more clutter — 5–10 is a good watchkeeping default.

5.4 Symbol amplifier

At a wide zoom, true-to-scale ship symbols can become specks. The symbol amplifier multiplies symbol size — ×1, ×2, ×5, ×10 — without changing anything else, so you can keep small craft visible when zoomed out. It's purely a visual aid; the underlying positions are unchanged. (Drop it back to ×1 when you zoom in close.)

5.5 Vessel names and labels

As vessels broadcast their static data (name, callsign, IMO, dimensions), AIS Watchkeeper quietly learns and remembers them per MMSI in a small on-disk register. That's why a vessel that arrived as a bare number gradually gains a name — and why it's already named the next time it appears, even before it re-broadcasts. You read this register in the Vessels tab (Section 8).

Each vessel also carries a label: its name (up to ten characters) on the first line and, on a second line, its heading and speed — for example 351° - 20 kn. The label sits a fixed distance off the vessel on its starboard quarter, joined to the symbol by a short leader line so it's clear which ship it belongs to even in a crowd. Vessels reporting a static status — moored or at anchor — show the name only, since heading and speed carry no meaning there. The Ship labels toggle in the Settings box turns the labels on and off.

A vessel's label, set off on the starboard quarter and joined to the symbol by a short leader line — here the heading-and-speed line reads 69° - 7 kn (the name sits on the line above once it has been learned). The green line is the vessel's COG speed vector.

5.6 Plotting, and the display switches

The Settings box has a plot vessels dropdown that decides which vessels are drawn on the map:

• all vessels (default) — every decoded vessel is drawn on the liveFeedAIS layer.
• my fleet — only the vessels on your My fleet watchlist are drawn (Section 8.3), so the map shows just the ships you care about while the feed still decodes everything.
• off — nothing is plotted; the plugin keeps decoding and counting traffic without drawing it.

Near the connect controls, above the Settings box, is a Show AIS only checkbox — it filters the live sentence log on the tab down to AIS messages, hiding any other NMEA traffic (e.g. GPS sentences) sharing the feed. This affects the on-screen log only, not the map.

Two more switches sit in the Settings box: Bind vessels to fairways connects each vessel to the Dutch fairway network and is the foundation of the Routes features (Section 9), and Audible chime on alarm governs the Guardian's alarms (Section 7).

The Settings box also holds two display selectors — chart light (day / dusk / night, Section 5.8) and units (nautical / metric / imperial, Section 5.9), covered next.

5.7 Losing contact — stale targets

A vessel that stops transmitting doesn't linger forever. If no position is heard from a target for 20 minutes, AIS Watchkeeper removes it from the map, from its trail and from any route binding, keeping the picture current. Whether the removal is noted depends on coverage: if the feed was still live at the time — you were hearing other vessels — the target counts as a genuine lost target and a line is written to the event log; if the whole feed had gone quiet (an outage), the removal is silent, since the vessel simply went out of coverage. A target that starts transmitting again reappears normally.

5.8 Day, dusk and night

The chart light dropdown in the Settings box switches the whole display between three brightness modes, the way an ECDIS does:

• Day — the normal bright chart.
• Dusk — a dimmed, muted picture for twilight.
• Night — a dark, low-glare picture to protect your night vision.

Choosing a mode changes several things together so the picture stays coherent: the map background, the basemap (dimmed and desaturated for dusk/night — an OpenStreetMap basemap is pre-drawn and can't be recoloured, so it is darkened rather than restyled), the vessel labels (light text on a dark halo at night), the route-leg strip, and the QGIS interface theme itself (dusk uses QGIS's "Blend of Gray", night uses "Night Mapping"). Your choice is remembered between sessions.

Two things worth knowing. Switching the mode changes the whole QGIS window's colours, not just the AIS panel — that's deliberate, so nothing glows white beside a dark chart. And on the next start the map picture is restored to your chosen mode, but the QGIS interface theme is left as you have it until you pick a mode again, so the plugin never overrides your own QGIS theme setting behind your back.

5.9 Units

The units dropdown sets the unit system for every readout in the plugin — ship labels, the Vessels tables, the route strip, positions, everything:

• Nautical (default) — speed in knots, range in nautical miles (cables under 1 nm), vessel dimensions and depth in metres, along-route distance in nautical miles, and positions as degrees + decimal minutes (e.g. 51° 20.52' N 003° 49.81' E).
• Metric — speed in km/h, distance in km / m, dimensions in metres, positions in decimal degrees.
• Imperial — speed in mph, distance in statute miles (feet for short ranges), dimensions in feet, positions in degrees + decimal minutes.

Bearings stay in degrees in every system. The one value that does not change is the Routes tab's Bind width, which is always in metres — it's a tuning tolerance you type, not a readout. Switching units re-labels everything live, and your choice is remembered between sessions.

6. Receiver position & coverage mapping

6.1 Why set your receiver position

Telling AIS Watchkeeper where your antenna is does two things:

1. It anchors coverage mapping — every cell of received traffic is stamped with this position (Section 6.4).
2. It's the reference point for the Vessels list — the Bearing and Distance to each nearby vessel are measured from here (Section 8).

You can run without it — vessels still plot, the Guardian still alarms, and traffic still binds to routes — but coverage and the nearby bearing/distance need it.

6.2 Setting your position

On the AIS stream tab, click Set own position… and choose how to give it. AIS Watchkeeper prefers a real GPS fix, but you can always place the point by hand:

• From QGIS GPS — if you have a GNSS receiver (a USB GPS puck, or a combined AIS/GPS unit), let QGIS handle the device and read the fix straight from it. Connect the receiver once in QGIS's own GPS Information panel (View → Panels → GPS Information, then Connect — QGIS finds the port and baud itself), and click From QGIS GPS: your antenna position is taken from the current fix. It is read once and not tracked — AIS Watchkeeper is a watchkeeping console, not a chart plotter, so it never chases the GPS live. If QGIS has no GPS connected yet (or hasn't got a fix), the plugin says so and points you back to that panel, and offers the map pick instead.
• Pick on the map — click your antenna's location on the map. The point is reprojected automatically, so it doesn't matter what coordinate system the map is in.
• Type it — enter lat, lon in decimal degrees (EPSG:4326), e.g. 51.333, 3.833. (Used automatically when there's no map canvas to click.)

Automatic from a combined receiver. If your AIS feed itself carries GPS sentences — many combined AIS/GPS receivers interleave their own position on the same serial or TCP stream — AIS Watchkeeper picks up the first valid fix and sets your position from it automatically, once per connection, with no clicking at all. A position you set by hand always takes precedence over this.

Your position then shows on the map as a single home marker (a house symbol, or a bold star as a fallback). To move it, just set it again.

6.3 It's remembered

Your receiver position is saved, so it's restored the next time you open the project and coverage resumes accumulating under it automatically — you don't re-enter it each session.

6.4 Coverage mapping

As traffic comes in, AIS Watchkeeper records where it actually hears vessels, building a live picture of your real-world reception — and, just as usefully, your blind spots. It does this on a grid: each small cell counts how many receptions it has collected, split by transponder class.

• Class A (the 12.5 W transponders carried by commercial vessels) is drawn in blue.
• Class B (the 2 W transponders on smaller craft) is drawn in orange.
• Each cell's dot grows with reception density — the more hits in a cell, the bigger the dot — so strong, reliable coverage stands out from the fringes where you only occasionally hear a vessel. Because Class A transmits at far higher power, you'll typically see its blue reaching much further out than the orange Class B.

The coverage layer is added to your project but switched off by default, so it doesn't clutter the live picture. To see it, open the Layers panel (Section 3.1) and tick the coverage layer. Turn it off again the same way.

Coverage is kept separately per source, so different sources never blur together. For a local receiver it is stamped with the antenna position you set, so moving to a new position starts a fresh survey while the old one is kept — you can compare reception from different sites. An internet source is tracked under its own identity instead: a fixed-footprint feed such as Kystverket keeps its own coverage map, and a position-based feed such as aisstream.io is tracked around the position you set. Switching source therefore switches to that source's own coverage picture, rather than overwriting your antenna's.

6.5 Watching coverage build

The Event log tab shows a coverage-status caption, and — when event logging is on — logs each time a vessel first comes into or drops out of coverage. So beyond the map picture, you get a running record of coverage changes over time. The logging side of this is covered next.

7. The Guardian

The AIS Guardian watches guard zones you draw on the map and raises an alarm when a vessel crosses them — the core watchkeeping function. It also keeps a log of vessel events. Everything here lives on the AIS Guardian tab.

Guard zones (red) drawn around the lock chambers at Terneuzen, watching live traffic; a vessel entering an armed zone raises an alarm and an Event-log entry.

7.1 The tab at a glance

Top to bottom: a green Feed live light, an Edit selected zone… button, the Alarms box (two alarms plus an event-logging switch), and the guard-groups editor.

The AIS Guardian tab — the Feed-live light, the three alarm switches (Alarm 1/2 plus the log-only event switch), and the guard-groups editor with New / Delete / Add MMSI / Remove.

7.2 Drawing a guard zone

A guard zone is a polygon you draw with QGIS's native editing tools, exactly as described in Section 3.3: select the guardZones layer, Toggle Editing, Add Polygon Feature, click out the shape, right-click to finish, then Save Layer Edits.

The moment you finish the polygon, the Guardian's zone form opens:

• Name — a label for the zone (shown in alarms and the log).
• Armed — the zone's own on/off switch (on by default). An unarmed zone is kept but never alarms.
• Alarm on entry (Alarm 1) — alarm when a vessel enters or sits inside (on by default).
• Alarm on exit (Alarm 2) — alarm when a vessel leaves (off by default).
• Target — All vessels, or Guard groups with a checklist of your groups (Section 7.5). Pick one or more groups to watch only those vessels.

Two save-time failsafes stop you from creating a zone that can never fire: you can't save a group-targeted zone with no group selected, and you can't save a zone with neither entry nor exit ticked.

To change a zone later, select it on the map ( Select Features) and click Edit selected zone… on this tab.

7.3 The three switches

The Alarms box holds the master switches. A zone only acts when the relevant master switch here is on:

• Alarm 1 — Guard zone (entry / within) — fires when a targeted vessel enters or is inside any armed zone. Its red light glows while any entry incident is open.
• Alarm 2 — Exit / left-zone — fires when a targeted vessel leaves. Its red light glows while any exit incident is open.
• Log vessel events (coverage in/out + nav-status) — log-only, no chime, no light. Records when vessels first enter or drop out of your reception coverage, and when a vessel changes navigation status (e.g. moored → under way). These go to the Event log only.

While a vessel is triggering an alarm, its name also turns red in the Vessels → Nearby list (Section 8), so you can spot the offending contact in the list at a glance, not just on the map.

Think of alarming as two-level gating: a zone fires only when the master switch is on and the zone is armed and the vessel is a target. That lets you arm a whole set of zones but silence them all with one master switch, or leave the master on and disarm a single zone.

7.4 How detection behaves

A few deliberate behaviours make the alarms trustworthy:

• Segment-based — the Guardian tests the track between two consecutive fixes, not just the dots. A fast vessel reporting infrequently can't skip across a thin zone unseen.
• One incident per visit — a 60-second exit grace absorbs tide and GPS jitter, so a vessel loitering on a boundary registers as a single incident, not a flurry. Entry is reported immediately; an exit is confirmed once the grace expires. A genuine leave-and-return after the grace counts as two incidents.
• Self-clearing light — the red light simply reflects whether any incident is currently open. There's no acknowledge step and nothing to reset.

7.5 Guard groups (watching specific vessels)

A guard group is a named set of MMSIs — a watchlist. The editor at the bottom of the tab lets you create and name groups, and add or remove MMSIs in each. Once a group exists, you can target a zone at it (Section 7.2) so the zone alarms only on those vessels.

The fastest way to populate a group is from the Vessels tab: right-click a vessel and choose Copy to group (Section 8). Use groups for a watchlist of vessels of interest; use All vessels on a zone when you want any intrusion to alarm.

7.6 What happens when an alarm fires

On a real alarm (Alarm 1 or 2), three things happen together:

1. An audible chime — if Audible chime on alarm is ticked. That toggle sits in the Settings box on the AIS stream tab (on by default) and governs the Guardian's alarms.
2. A message-bar line across the top of QGIS, naming the alarm kind, the vessel's MMSI, the zone, and what happened.
3. An entry in the Event log (Section 8 covers the Event log tab).

The log-only events from the third switch (coverage in/out, nav-status) are silent — no chime, no message bar — and appear only in the Event log.

8. Vessels

The Vessels tab is a live table of traffic, with three views you switch between using the Nearby / Register / My fleet radio buttons at the top.

8.1 Nearby

Nearby lists every vessel currently being received, measured against your receiver position (Section 6) and sorted nearest first. Columns:

• MMSI — the vessel's identity number.
• Vessel name — its learned name (blank until it broadcasts one). A vessel currently triggering a Guardian alarm shows its name in red here, matching the map.
• Bearing — the compass bearing from your position to the vessel, in degrees.
• Distance — straight-line range from your position, in nautical miles.
• Fairway — the name of the fairway the vessel is bound to, or — if it isn't on one.
• Flow — its direction of travel along that fairway. A vessel that's moored, at anchor or aground shows idle instead of a direction (so a ship sitting beside a fairway doesn't read as "moving").
• Route km — how far along the fairway it is, in kilometres (the fairway's linear-referencing measure).

Because it's sorted by distance and refreshes live, the top of the list is always your closest traffic. Click any row to pan and zoom the map to that vessel.

Nearby: traffic sorted nearest-first, each row showing bearing and distance from your position, plus the fairway, flow and route-km from binding (idle vessels show no flow).

If no receiver position is set, Nearby stays empty — Bearing and Distance have nothing to measure from. Set your position (Section 6.2) to populate it.

8.2 Register

Register switches the table to the learned vessel database — every vessel AIS Watchkeeper has ever seen and remembered, not just those in range right now. It's backed by vessel_names.xml in your profile, so it persists across sessions and grows over time. Columns:

• MMSI, Vessel name, Vessel callsign, Vessel ID, Vessel Length, Vessel Beam, Vessel Type.

A search box (active in this view) filters the table as you type, matching across the fields — handy for finding a particular ship in a long history.

Register: the learned ship database — MMSI, name, callsign, vessel ID, length, beam and type — for every vessel ever seen, filtered live by the search box.

8.3 My fleet

My fleet is your own watchlist — the ships you want to keep an eye on regardless of the rest of the traffic. Switch to it with the My fleet radio button; the view lists the vessels you've added, with the same columns as the Register, and its search box filters as you type.

Adding and removing. In any Vessels view (Nearby, Register or My fleet), right-click a vessel and choose Add to my fleet; to drop one, right-click it and choose Remove from my fleet. Your fleet is saved in your profile (my_fleet.json, Section 11.1), so it persists across sessions.

Plotting just your fleet. Set the plot vessels dropdown (Section 5.6) to my fleet and the map draws only these vessels — a clean picture of just your ships, while the feed keeps decoding everything else.

8.4 Copy a vessel into a guard group

Right-click any vessel row and choose Copy to group → [group] to add that vessel's MMSI to one of your guard groups (Section 7.5). It's the quickest way to build a watchlist: spot a vessel of interest in the list, right-click, done — no typing MMSIs by hand.

8.5 The Event log

The fifth tab, Event log, is the running record. Every alarm (zone entry/exit) and every logged event (coverage in/out, nav-status changes, stream-health summaries) lands here with a timestamp, newest first. Refresh reloads it, and Export writes the whole log to a CSV file for reporting or archiving. A coverage-status caption sits beside the export control.

The Event log: timestamped rows — here a run of LOST TARGET events (a target unheard for 20 minutes while the feed stayed live) with time, MMSI and last position. The coverage caption (bottom) tracks Class A/B cell counts; Refresh reloads and Export CSV saves the log.

9. Routes & fairway binding

This is what sets AIS Watchkeeper apart from a plain plotter: it ties each vessel to the Dutch fairway network, so you can think in terms of fairways and traffic flow rather than just dots on water. Everything in this section depends on Bind vessels to fairways being on (the switch in the AIS stream tab's Settings box, on by default).

9.1 What fairway binding is

As vessels move, AIS Watchkeeper matches each one to the fairway it's actually travelling on, and works out how far along that fairway it is (a kilometre measure) and which way it's heading. Those three facts — fairway name, route-km, flow direction — are what fill the Vessels tab (Section 8) and drive the route strip (Section 9.4).

The matching is deliberately careful, so vessels don't flicker between nearby fairways:

• It binds on the vessel's track, not a single position — it watches the course made good over at least three fixes and picks the fairway that best matches both proximity and the direction the vessel is actually travelling. So where several fairways run close together, a vessel binds to the one it's moving along, not merely the nearest line.
• A vessel that drops below about 2 knots for several fixes is detached from its fairway — a moored or anchored ship stops being glued to whatever fairway it happens to sit beside. It re-binds once it's making way again. (This is why such vessels read idle in the Vessels list.)

9.2 The fairway chart layers

Two related datasets sit behind this, and they show up differently on the map:

• The routes used for binding are full-length, properly-named fairways (the Westerschelde, for instance, is one ~105 km line). These carry the kilometre referencing. They're bundled with the plugin, so binding works fully offline.
• A separate "vaarwegen" passages layer is a display-only chart layer — the individual named stretches (Honte, Pas van Terneuzen, Vlissingen Rede, and so on), drawn as thin reference lines. To keep the map clean, it only appears when you're zoomed in past about 1:12500. Zoom in and the fairway detail fills in; zoom out and it tidies away. You can toggle it like any layer from the Layers panel (Section 3.1).

9.3 The Routes tab

The Routes tab is a live table of every fairway that currently has traffic on it, sorted by fairway name so the list stays stable and doesn't jump around as vessel counts change. Columns:

• Fairway — the route's name.
• Inbound / Outbound — how many vessels are moving each way along it.
• Idle — how many bound-but-stationary vessels sit on it.
• Bind width (m) — the per-route binding tolerance: how far, as a perpendicular distance from the centreline (to either side), a vessel can be and still bind. Editable.

Custom routes you've drawn appear here in blue, tagged (custom), mixed in with the bundled fairways and behaving the same way — counts, bind width, and a leg you can open (Section 9.8).

The Routes tab — every fairway carrying traffic, sorted by name, with Inbound / Outbound / Idle counts and an editable Bind width (m). The default 150 m suits canals; widen a broad tidal fairway so ships sailing off the centreline still bind.

Click any row (except the Bind-width cell) to open that fairway's leg in the route-strip monitor (Section 9.4). The table refreshes every couple of seconds and keeps your selected route highlighted across refreshes.

Tuning bind width. A single fixed tolerance doesn't suit every fairway. The value is the perpendicular distance measured outward from the fairway centreline — not the total corridor width — so the fairway effectively spans that distance on each side of its centreline. A tidal fairway like the Westerschelde mouth is nearly a kilometre wide and ships legally sail well off the centreline, so a tight tolerance would drop them as "off-fairway." Double-click the Bind width (m) cell and widen it — for a fairway where ships run up to ~650 m off the centreline, set roughly 650, which reaches ~650 m to either side. Narrow canals and closely-spaced parallel routes keep the tight default so they don't mis-bind. Widening never steals a vessel that's genuinely closer to another route — the nearest-plus-alignment rule still decides — it just lets an off-centre vessel bind to the fairway it's really on (reading as a slightly lower-confidence bind). Values are saved per route and reload next time.

Seeing the corridor on the chart. To see how wide a route's bind width is, turn on the Route bind-width layer in the Layers panel (Section 3.1) — it's added switched off. When you zoom in, each fairway shows two thin dashed lines, one on each side of its centreline, marking the binding corridor; a vessel between them is within tolerance of that route. Widen a route's Bind width and its corridor visibly fattens, so you can set the tolerance by eye. Like the fairway detail, the corridor only draws when you're zoomed in, to keep the chart clean.

9.4 The route-strip monitor

Click a fairway in the Routes tab and its leg opens in a separate window — the strip monitor. It lays the whole fairway out as a straight axis marked in kilometres, and places every vessel on it at its route-km, so you read a winding 100 km fairway as one clean line.

The Hartelkanaal leg as a strip (km 0–20.5). Outbound ▲ to one side, inbound ▼ to the other; bridges branch off by route-km (Hartelbrug, Harmsenbrug, Suurhoffbrug). Where symbols crowd they fan out perpendicular from the axis — slowest nearest the line, fastest furthest out.

How to read it:

• Outbound vessels sit above the axis, inbound below — so the two traffic streams separate at a glance.
• Each vessel is coloured by speed — a heat ramp from green at ~2 knots through to red at 20 knots and above (grey if the vessel isn't reporting speed). Fast movers jump out.
• Stationary vessels are hidden — anything slower than ~2 knots is dropped from the strip so it doesn't clutter, leaving only the traffic that's actually moving. Ship names are automatically nudged apart so they stay readable even in a busy cluster.

Controls on the strip's toolbar:

• ⟳ Portrait toggles the layout between horizontal and vertical — a real re-layout, so labels read normally either way. Use whichever fits your screen or second monitor.
• Refresh re-fits the view to the whole leg. The strip also refreshes itself every couple of seconds.
• You can wheel-zoom about the cursor and drag to pan; your zoom and pan are kept across the live refreshes, and only an explicit action (open, Refresh, rotate, resize) snaps back to the full-leg fit.
• ← Overview steps back out of the leg.

The strip is wired to the main map: click a ship on the strip and the QGIS map recentres, zooms and flashes that vessel — so you can go from "who's that on the strip" to "show me on the chart" in one click.

9.5 Bridges and locks (live from the RWS service)

When you open a leg, AIS Watchkeeper fetches that fairway's bridges and locks from the Rijkswaterstaat FIS-VNDS service and draws them on the strip as labelled markers rising from the axis: purple for a bridge, orange for a lock, named, positioned by their own route-km.

This is the one place the plugin reaches the internet. The fetch is per-route, cached, time-limited and entirely best-effort: if you're offline or the service hiccups, the strip simply opens without the bridge/lock markers and the live AIS feed is never affected. So bridges and locks need a connection; binding, the strip and everything else work fully offline.

9.6 Your own reference markers

Bridges and locks come from the service, but you can add your own points to the strip — buoys, VTS sector boundaries, berths, anything you want as a landmark along the fairway. You place these with QGIS's native editing as described in Section 3.4 (the Route reference markers layer), and they appear on the strip as teal diamonds, snapped to the nearest fairway and positioned by route-km exactly like the bridges and locks. They also feed the ETA tool below.

9.7 Route CPA and ETA

The Route CPA button predicts encounters along the fairway — which is what matters on a fairway, where two ships' paths are constrained to the same line.

• Two vessels: click Route CPA, then click two vessels on the same fairway. The strip predicts their meeting point and draws it — blue for a head-on meeting, green for an overtaking (one catching the other) — with each vessel's distance-to-go to that point.
• A vessel and a fixed object: click a vessel, then a bridge, lock or one of your markers, and you get that vessel's ETA and distance-to-go to the structure — useful for "when does this ship reach the lock."

A head-on route-CPA on the strip — the blue bar marks the predicted meeting point and time (here CPA 16:15), with the two closing vessels either side of it.

The same prediction on the main chart: the meeting bar (routeCPA 16:15) drawn at its real position across the Hartelkanaal, each vessel labelled with its distance-to-go (DTG).

Recalculate re-runs the prediction with the latest positions; Clear removes it. Each picked vessel is also marked with a blue dot on the main chart, so you can pick the two ships out of the traffic and tie the on-strip prediction to the real vessels on the map.

A vessel coupled to the active route-CPA, marked with a blue dot at its position so you can find it among the traffic on the chart. Its green line is the COG speed vector.

9.8 Custom routes (drawing your own)

The bundled fairway network is the Dutch one. Outside the Netherlands there's no bundled fairway to bind to — so AIS Watchkeeper lets you draw your own. A custom route is just a line you draw down the middle of a waterway and give a name; from then on it behaves like any other fairway — traffic binds to it, it appears in the Routes tab, and it gets its own leg strip with route-km, inbound/outbound, CPA and ETA.

Drawing one. Custom routes live on the Custom routes layer, and you draw them with QGIS's native editing exactly as in Section 3.3: select the layer, Toggle Editing, Add Line Feature, left-click each vertex down the waterway, right-click to finish, type a name, then Save Layer Edits and toggle editing off. Draw it down the centre of the channel, the way you'd draw a fairway centreline; vessels bind to it within the same perpendicular tolerance as any route (and you can widen that per route from the Routes tab, Section 9.3).

The direction you draw it sets inbound vs outbound. A custom route has no sea to orient itself by, so it takes its direction from how you draw it: travel in the same direction you drew the line (first vertex → last vertex) counts as inbound, the reverse as outbound. If the counts come out backwards for your waterway, just redraw the line the other way (or reverse its geometry with the Vertex tool).

Custom routes win ties. Where a custom route overlaps or runs close to a bundled fairway, a vessel within tolerance of both binds to your custom route, not the native one — so your own routes take precedence wherever you've drawn them. Everywhere you haven't drawn a custom route, native binding is completely unchanged.

They persist. Custom routes are saved in your profile (custom_routes.gpkg, Section 11.1) and reload every session, and edits take effect live — add, reshape or rename a route, save, and the binding picks it up within a couple of seconds. In the Routes tab they're shown in blue and tagged (custom) so you can always tell your routes from the bundled ones.

10. Voyage history

AIS Watchkeeper can keep a history of where vessels have been, segmented into voyages, so you can look back at a track later. It is off by default and entirely optional; you turn it on in the Voyage history box on the AIS stream tab.

10.1 Recording

Tick Record voyage history to start. Two choices shape what is kept:

• Detail — how much is stored, in three cumulative levels:
  1. Textual — each vessel's identity plus a log of events (entering and leaving coverage, navigation-status changes). No geometry.
  2. Voyages — the above, plus one line geometry per voyage.
  3. Full — the above, plus every individual transponder position as a point (the fullest record).
• Storage — where it goes:
  • GeoPackage — a single local file in your profile, created automatically. The status line shows how much disk it is using.
  • PostgreSQL / PostGIS — a shared database, chosen from a connection you have saved in the QGIS Data Source Manager (click Configure database… to pick the connection and the target schema). The first time you record, the plugin offers to create the tables for you. Credentials come from QGIS's own connection, so nothing sensitive is stored by the plugin.

A voyage begins when a vessel is under way and ends when it moors or anchors, or when it drops out of coverage for more than an hour. Only real ships are recorded — shore stations, aids-to-navigation and obvious decode glitches (impossible position jumps) are filtered out — so the history stays clean. The status line reports fixes received, rows written and any that were filtered.

The Voyage-history box on the AIS stream tab with the Detail dropdown open — the three cumulative levels: 1 Textual, 2 Voyages, 3 Full. The ? button (top-right, circled) opens this manual.

10.2 Looking back

The History tab: the stored-voyages table (vessel, MMSI, start / end UTC, duration, end reason, destination) with the search box, the time window and its last-hour / day / week presets, the map-view area filter, and the Show track / Show all tracks / Clear tracks / Export CSV / Delete history controls. The header shows how much is stored and how many rows are shown.

The History tab is the main way to browse what you have recorded: a sortable table of every voyage (vessel, MMSI, start / end in UTC, duration, end reason, destination), newest first. Three filters narrow it down: a name or MMSI search, an optional time window, and an optional "only voyages crossing the current map view" area filter. Then:

• Double-click a voyage (or select it and press Show track) to draw that voyage's track on the map and zoom to it.
• Show all tracks for vessel draws every voyage of the selected ship at once.
• Export CSV… saves the currently shown rows to a spreadsheet.
• Delete history… permanently clears the archive (see §10.3).

The header shows how much is stored (voyages, vessels, fixes) and the time span.

Two quicker shortcuts also pull a single track straight onto the map without opening the tab:

• From the event log — right-click an event and choose Show track (±5 min) to draw that vessel's track from five minutes before to five minutes after the event.
• From the register — in the Vessels tab (Register view), right-click a vessel and choose Past voyages… to list its voyages; pick one and its track is drawn and zoomed to.

Retrieved tracks land in an AIS history layer group. If there is no history stored yet, the tab and the shortcuts tell you so rather than drawing an empty map.

10.3 Clearing history

Delete history… (in the Voyage history box) permanently clears all recorded history from the active backend — it empties the PostgreSQL tables, or deletes the GeoPackage file — after a confirmation. If recording was on, it resumes into a fresh, empty store.

11. Reference & troubleshooting

11.1 Where your data is kept

Everything you create lives in one folder inside your QGIS profile, not in the plugin folder — so it survives plugin upgrades:

<your QGIS profile>/ais_nmea_source/

What's in it:

• Guard zones — the polygons you draw (ais_guardian_zones.gpkg).
• The Guardian store — your guard groups, the event log, and your saved receiver position (ais_guardian_store.gpkg).
• Coverage — the Class A/B reception cells (ais_guardian_coverage.gpkg, kept separate to avoid write contention).
• Vessel register — the learned ship database (vessel_names.xml).
• My fleet — your vessel watchlist (my_fleet.json, Section 8.3).
• Bind widths — your per-route tolerances (route_tol.json).
• Reference markers — your strip landmarks (markers.gpkg).
• Custom routes — the routes you've drawn (custom_routes.gpkg, Section 9.8).
• Voyage history — when you record to the local GeoPackage, the voyage archive lives in a history/ subfolder (history/ais_history.gpkg); recording to PostgreSQL/PostGIS keeps it in that database instead.
• A backups subfolder for the store.

To back up your whole setup, or move it to another machine, copy that one folder. (The fairway network itself — data/routes.gpkg and data/fairways.gpkg — ships inside the plugin and isn't something you edit.)

11.2 Troubleshooting

A Bluetooth/USB receiver doesn't appear in the Port dropdown. Most Bluetooth AIS units pair as a serial port and show up normally — click Refresh after pairing. If it still doesn't appear, it's most likely a Bluetooth Low Energy (GATT) device, which isn't supported (Section 4.1); contact the plugin developer.

Connected, but no vessels appear. Check the status counts on the AIS stream tab. If sentences are flowing but the AIS count stays zero, the baud rate is probably wrong (try Auto-detect, or 38400 vs 4800) or the feed isn't AIS (e.g. GPS-only). If AIS is being counted but nothing plots, make sure Plot vessels on map is ticked.

A TCP feed won't connect or asks to log in. The endpoint is secured — fill in the login dialog that appears (TLS, method, credentials) as described in Section 4.4.

Vessels show but don't bind to a fairway. Confirm Bind vessels to fairways is on. A vessel under ~2 knots is treated as idle and detached on purpose. If a moving vessel still won't bind, it may be sailing too far off the centreline — widen that route's Bind width in the Routes tab (Section 9.3).

The Vessels → Nearby list is empty. No receiver position is set; bearing and distance have nothing to measure from. Set it (Section 6.2).

The coverage map isn't visible. It's added switched off — tick the coverage layer in the Layers panel (Sections 3.1 and 6.4).

A route's strip has no bridges or locks. Those come live from the RWS service, so you're offline or it hiccupped. Everything else (binding, the strip, your markers) still works offline (Section 9.5).

QGIS crashes when you unplug a serial receiver (Windows). Hit Full stop before unplugging — it stops the reader cleanly first (Section 4.6).

A guard zone never alarms. Check the chain: the master switch (Alarm 1/2) must be on, the zone must be Armed, it must have entry and/or exit ticked, and if it's targeted at a guard group, that group must contain the vessel (Section 7).

The panel or map feels heavy on a modest laptop. AIS Watchkeeper sizes itself to your machine. At startup it briefly measures how fast this computer draws the map and picks a matching display profile, and it keeps an eye on the draw time while running. On a slower machine it eases off automatically — drawing vessels as light dots when you're zoomed out, thinning labels and trails, and repainting a little less often — and if a heavy feed is clearly overloading the display it steps down one further level on its own. None of this is a setting you manage; it just keeps the live picture responsive. You can lighten the load further by hand: reduce the Area radius on an internet source, or set plot vessels (Section 5.6) to my fleet or off so the map draws fewer ships while the feed keeps decoding everything.

12. Appendix

12.1 Licensing

AIS Watchkeeper (ais_nmea_source) is free software under the GNU General Public License v3.0 or later — the full text is in the bundled LICENSE file. Copyright © 2026 W.D. de Pooter; published under the byline Captain Ahab & Cosmo.

It bundles three pure-Python libraries (in libs/, so no pip or internet is needed to install them), each under its own permissive, GPL-compatible licence:

Library	Version	Licence	Purpose
pyserial	3.5	BSD-3-Clause	Serial port discovery and reading
pyais	3.1.0	MIT	AIS sentence decoding
attrs	26.1.0	MIT	pyais's runtime dependency

One further library, networkx (BSD-3-Clause), is used for the routable fairway graph but is not bundled — it's provided by QGIS's own Python. Route matching degrades gracefully if it's absent.

Data. The bundled fairway network (data/routes.gpkg, data/fairways.gpkg) is derived from Rijkswaterstaat FIS-VNDS open vaarweg/route data, and the live bridges and locks are fetched from the same service.

12.2 AIS messages decoded

AIS Watchkeeper reads both !AIVDM (other vessels) and !AIVDO (own vessel) sentences, reassembling multi-sentence messages automatically. The message types it uses:

• Position reports — types 1, 2, 3 (Class A) and 18, 19 (Class B): give each vessel's position, speed over ground, course, heading and navigation status. These decode immediately, one sentence each.
• Static and voyage data — type 5 (Class A) and type 24 (Class B, parts A/B): give the name, callsign, IMO/vessel ID, dimensions and ship-and-cargo type. These span two sentences, tied together on reassembly, and are what fill the vessel register and drive the ship-type symbology.

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