The open-source chartplotter setup, end to end.

What you're actually building

Before spending a dime, be clear about what this stack does and doesn't do. An open-source chartplotter based on Raspberry Pi + OpenPlotter + Signal K + OpenCPN gives you:

• A full-featured electronic chartplotter with vector and raster chart support, AIS target tracking, routing, and waypoint management
• A data hub that pulls everything off your NMEA 2000 bus — GPS, speed, depth, wind, engine, tank levels — and makes it available to apps, dashboards, and automation
• A web dashboard (Signal K) accessible from any phone or tablet on your boat's Wi-Fi, showing live instrument data in a browser
• An extensible platform — you can build custom dashboards in Node-RED, log data to InfluxDB for long-term trend analysis, or pipe everything to Home Assistant

What it's not is a plug-and-forget appliance. A $3,000 Garmin or Simrad MFD boots in 20 seconds, has a waterproof touchscreen, and survives being cold-soaked and salt-sprayed without complaint. A Pi in a plastic case on your nav table does not. This build is for people who want data sovereignty, programmability, and the satisfaction of a system they built and can fix themselves — not people who want the least friction on a Saturday daysail.

The parts list

Every price is checked against retail sources as of April 2026. Prices fluctuate; Pi availability in particular has been volatile. This list assumes you're buying new; used gear can easily cut the cost by 30–40%.

Honest subtotals: the iKonvert is nearly half the build cost. If your boat already has a Wi-Fi gateway (say, the Yacht Devices YDWG-02 we recommended in the gateway guide), you can skip the iKonvert entirely and connect the Pi to it over Wi-Fi — Signal K speaks TCP natively. That cuts the build to around $230.

The featured parts, in detail

Most parts in the list above are commodity items — an SD card is an SD card. But three components define the build, and each deserves a closer look.

What you don't need

A few things you'll see in other guides that are genuinely optional:

A chart package

OpenCPN reads free NOAA charts (US waters), free OpenSeaMap tiles (global), and most raster formats. You don't need to buy C-MAP or Navionics chips. That said, if you boat outside US waters, a $50 Navionics subscription or the free OpenSeaMap/OSM charts will serve you well — but it's a software decision, not a hardware one.

A fan

The Pi 5's active cooler includes a small fan. For a boat cabin install, passive aluminum cases plus the active cooler are enough. A separate case fan is overkill and adds failure points.

An UPS hat immediately

You'll eventually want one — losing power mid-write is how SD cards get corrupted — but for the first build, wire the Pi to a switched 12V-to-USB-C converter. Add a UPS later when you know the setup is keeping you happy.

Three monitors

One at the helm, one below, one at chart. The beauty of Signal K is that any phone, tablet, or laptop on the boat's Wi-Fi becomes a display. Build the base station first. Decide later whether additional screens are worth the complexity.

How the stack fits together

OpenPlotter isn't really one program — it's a distribution, a custom Raspberry Pi OS image with a curated set of marine tools pre-installed and pre-configured. The three that matter most:

• Signal K Node Server — the data hub. Pulls data off your gateway, normalizes it into Signal K's modern JSON format, and makes it available via HTTP/WebSocket/TCP to anything that wants it.
• OpenCPN — the chartplotter application. Shows charts, draws AIS targets, plans routes. Reads data from Signal K (since OpenCPN 5.2).
• The OpenPlotter settings apps — a set of small GUI utilities for configuring the gateway connection, network, sensors, and Signal K. The reason you install OpenPlotter instead of doing this by hand is to avoid wrestling with a hundred config files.

    NMEA 2000 BUS
    (your boat's instruments)
          │
          ▼
    ┌──────────────┐
    │  iKonvert    │  USB gateway
    │  (or YDWG-02)│
    └──────┬───────┘
           │  USB or Wi-Fi
           ▼
  ┌─────────────────────────────────┐
  │       Raspberry Pi 5            │
  │                                 │
  │  ┌──────────┐    ┌──────────┐  │
  │  │ Signal K │ →  │ OpenCPN  │  │
  │  │  Server  │    │  5.10    │  │
  │  │ :3000    │    │          │  │
  │  └────┬─────┘    └──────────┘  │
  │       │  WebSocket / TCP       │
  └───────┼─────────────────────────┘
          │
          ▼  over boat Wi-Fi
   ┌────────────────┐
   │ Phones, tablets│ ← dashboards,
   │ remote laptops │   charts, apps
   └────────────────┘

The key insight: Signal K is the single source of truth. Every piece of marine data enters the system through Signal K and every display pulls from it. OpenCPN isn't reading the gateway directly — it's reading Signal K. Your phone's dashboard app isn't reading the gateway either. This keeps things clean and means you can add new displays later without rewiring the whole stack.

The build, step by step

First run: making sure data actually flows

The most common failure mode for a first-time builder is "everything installed, but OpenCPN doesn't show my boat." Here's the checklist we run through every time:

Verify Signal K is receiving data

Open http://10.10.10.1:3000 → Data Browser. You should see a tree of live values. If this is empty:

• Check Server → Connections. The iKonvert connection should be green and showing a packet rate.
• If red or gray, check Server → Data Connections log. Look for errors about serial port permissions — common on first install.
• Run ls -l /dev/ttyUSB* from an SSH session. The iKonvert's serial device must be readable by the pi user. OpenPlotter handles this automatically but occasionally needs a reboot.

Verify OpenCPN sees Signal K

In OpenCPN, bring up Options → Connections. The Signal K connection should show a small green icon and a non-zero rx/tx count. If not:

• Confirm the port is 3000, not 3443 (the secure one, which needs certs configured)
• Try 127.0.0.1 instead of localhost if you get DNS resolution issues
• Restart OpenCPN — the Signal K connector sometimes doesn't re-initialize after a config change until restart

OpenCPN configuration that matters

OpenCPN has roughly six hundred settings. Most can be left alone. A few are worth changing on first use:

Under Options → Display → General

• "Enable touch screen interface" if you're using the 7" Pi touchscreen — tap targets enlarge
• "Full Screen Toolbar" unchecked if your screen is 7" — the toolbar eats too much real estate otherwise

Under Options → Ships → AIS Targets

• "Show AIS target tracks" on — useful for spotting stopped vs moving vessels at a glance
• "CPA/TCPA alert" on with defaults — warns when a close-passing vessel is imminent

Under Options → Ships → Own Ship

• Set your boat's size dimensions properly (length, beam, draft). This shows your actual outline on the chart, not a generic arrow.
• Under "Heading Predictor," turn on heading predictor and set it to "VMG based on boat speed" — shows where you'll be in 6 minutes

Under Plugins

OpenCPN has a genuinely excellent plugin ecosystem. A few we recommend turning on right away:

• DashT — dashboard overlay with engine/wind/depth gauges, pulling directly from Signal K
• WMM — World Magnetic Model, corrects your compass readings. On by default on new installs.
• Weather_Routing — GRIB-based route optimization. Niche but delightful.
• Squiddio — shared routes and waypoints with other OpenCPN users

Adding a phone or tablet as a remote display

Signal K's killer feature: anything with a web browser on your boat's Wi-Fi can display your data. No app install needed.

From your phone, while connected to the openplotter hotspot (or your boat's Wi-Fi if you've joined the Pi to it), open http://10.10.10.1:3000. You'll see the Signal K admin dashboard. But there's more:

• Web-based instruments — /@signalk/instrumentpanel gives you configurable gauge layouts. Build a wind/speed/depth panel, pin it to your iPad's home screen, and it behaves like a native app.
• Freeboard-SK — a proper web chartplotter that runs entirely in the browser. Install it from the Signal K Appstore (Admin UI → Appstore → install freeboard-sk). Works on phones and tablets.
• Native apps that speak Signal K — iNavX, SEAiq, Aqua Map, and several others connect directly to Signal K over your boat's Wi-Fi and use its data the same way OpenCPN does.

For a cruising couple, a typical setup is: the Pi + 7" touchscreen mounted at the nav station showing OpenCPN, and an iPad at the helm showing Freeboard-SK or an instrument panel. Both are reading the same Signal K server, both always in sync, neither needs internet.

The realistic limitations

No guide should oversell. A few things this stack genuinely doesn't do well compared to a commercial MFD:

Sunlight readability

The official 7" Pi touchscreen is 250 cd/㎡. An MFD is 1,000+ cd/㎡. In direct sun, the Pi display becomes a mirror. The fix is a sun-readable marine monitor at 10–12" for $300–400, which pushes the build cost up to roughly where a low-end dedicated chartplotter starts. Be realistic about where the Pi screen will actually live.

Waterproofing

The Pi, its case, and the screen are not waterproof. A $40 Garmin or Raymarine MFD enclosure is rated to IPX7 and can be hosed down. If your boat gets truly wet inside — open cockpit, spray, leaks around the companionway — the Pi needs a real waterproof enclosure (custom fabricated, $100+) or you need to mount it belowdecks.

Boot time

Raspberry Pi 5 with SD card cold-boots OpenPlotter in about 45 seconds. A Garmin MFD cold-boots in 15. This is annoying mostly the first time of the day, but if you lose power mid-trip you'll notice the minute before charts come back up. Moving to NVMe SSD cuts the boot time roughly in half.

Support when it breaks

If your MFD dies, you call the manufacturer. If your OpenPlotter breaks, you post on the OpenMarine forum. The community is helpful and the responses are thorough, but you're not getting a same-day warranty replacement. Keep a backup SD card with a tested OpenPlotter image; it's the cheapest insurance on the boat.

Where to go from here

Once the base stack is running reliably, the fun part starts. Four directions worth exploring:

Long-term data logging

Install InfluxDB and Grafana via the Signal K plugin marketplace. Suddenly you have a real database of every piece of boat data — battery voltage trends over a season, engine hours, fuel burn, wind patterns. This is where an open-source stack starts to pull ahead of commercial MFDs: a Raymarine will show you your battery voltage right now, but it won't draw you a three-month graph of how your battery bank has been degrading.

Home Assistant integration

Signal K has a Home Assistant plugin that makes all your boat data available to home-automation dashboards. This is especially useful if you run Home Assistant for your house anyway — your boat becomes just another room with sensors.

Custom alerts

The Signal K notifications plugin lets you create arbitrary rules. Bilge on more than 30 seconds? Push notification to your phone. Battery below 12.0V? Email alert. Wind exceeds 25 knots at anchor? Sound the siren. The rule language is JSON and lightweight enough that non-programmers can handle it with a template from the forum.

A proper custom dashboard

Node-RED (included in OpenPlotter) gives you visual flow-based programming for building custom dashboards. Design a single-screen "departure checklist" display that shows battery voltage, fuel level, engine temp, AIS target count, and weather GRIBs all at once. Most builders eventually make something like this and wonder why the factory-built MFDs don't offer it.

Frequently asked questions

Do I need to buy a chart package like C-MAP or Navionics for an OpenCPN chartplotter?

No. OpenCPN reads free NOAA charts for US waters, free OpenSeaMap tiles globally, and most raster chart formats. A Navionics subscription is optional for non-US cruising at around $50/year, but it's a software decision, not a hardware requirement.

How does an open-source Raspberry Pi chartplotter compare to a commercial MFD in sunlight?

The official 7-inch Raspberry Pi touchscreen is rated at 250 cd/m2 while a commercial MFD is 1,000+ cd/m2, so the Pi screen becomes a mirror in direct sun. A sun-readable marine monitor at 10 to 12 inches costs $300 to $400, which pushes the total build cost close to a low-end dedicated chartplotter.

Is a Raspberry Pi chartplotter waterproof?

No. The Raspberry Pi, its case, and the official touchscreen are not waterproof. A commercial MFD is rated to IPX7 and can be hosed down. For wet installs you need a custom waterproof enclosure starting around $100, otherwise mount the Pi belowdecks.

How long does a Raspberry Pi chartplotter take to boot?

A Raspberry Pi 5 with a microSD card cold-boots OpenPlotter in about 45 seconds, versus around 15 seconds for a Garmin MFD. Moving to an NVMe SSD cuts the Pi boot time roughly in half.

What does a Raspberry Pi 5 OpenPlotter chartplotter build cost?

A complete new-hardware build with Raspberry Pi 5, official 7-inch touchscreen, Digital Yacht iKonvert NMEA 2000 gateway, microSD card, case, cooler, and power supply totals about $445. If your boat already has a Wi-Fi NMEA 2000 gateway, you can skip the iKonvert and bring the build down to around $230. All software (OpenPlotter, Signal K, OpenCPN) is free.