Running a Raspberry Pi aboard a boat has been a popular thing to do for a number of years. I’ve had them on every boat since the Pi first came out. Connecting them to a NMEA 2000 network, and powering them off a DC battery bank has required a bit more work up until now.
Why a Pi?
There are many reasons to have a Raspberry Pi connected to your boat network that I can think of. My main reason is to run a Signal K server on it, have it connected to my NMEA 2000 network, and leverage the hundreds of plugins and pieces of software that you can install to create dashboards, gather data, set alarms and alerts, and so much more.
On sailboats in particular, I loved having a Pi on board because I could have an always-on computer that didn't take a ton of power, had a decent amount of CPU power, and use it to monitor things while I was away.
The old way...
The first step in connecting a Pi to the boat was to find a proper power supply. Raspberry Pi's run off of USB power which is 5V, and not generally available on the boat in a permanent way. I always wanted mine to run off of the 12v DC battery bank without any connection to an AC outlet, inverter, or USB converter that isn't hard wired. I have had good luck with this 12v-5v converter from Tobsun, and I particularly like it because it has four screw down terminals on it, making it easy to connect cabling.
Once the power problem is solved, connecting the Pi to the boat network involved either an Actisense NGT-1 USB adapter ($) or a canable.io adapter to get it on the NMEA 2000 network. Both have pros and cons and require connecting to a USB port on the Pi, plus some configuration.
An easier way....
A reader and Instagram follower (thanks Ilker Temir!) pointed me to an add-on board, or HAT, for the Raspberry Pi called the PICAN-M, and I was intrigued. I ordered one from Copperhill Technologies here in the US and it arrived a few days later. The original manufacturer of the board is SK Pang Electronics out of the UK.
I had a Raspberry Pi 4 that I had been playing around with ever since it came out, but didn’t have a clear purpose for it. I decided to install the PICAN-M on it, and then try out a few different things. I generally purchase the CanaKit bundle when I am buying a Raspberry Pi (I think I have about 15 right now doing various things at home and on the boat) as they tend to include a nice power supply, case, cables, and mainstream brand SD card, but you can get them cheaper without those pieces if you prefer. In this case, the extra parts and pieces were important when I bought the Pi to do testing in general, but were not necessary since the PICAN-M provides power, and the case provided by CanaKit won't work.
The PICAN-M is a pretty simple, yet well designed board. It has a NMEA 0183 terminal block and NMEA 2000 port on the left side in the picture above, and the connector for the Raspberry Pi on the right hand side.
There is a really nice schematic and user guide that SK Pang have provided on their website. The board looks very well built with clearly labeled bits. Here's what SK Pang say the board is capable of:
- CAN connection via Micro-C connector
- 120Ω terminator ready
- SocketCAN driver
- appears as can0 to application
- NMEA 0183 (RS422) via 5-way screw terminal
- appears as ttyS0 to application
- LED indicator (GPIO22)
- Qwiic (I2C) connector for extra sensors
- Include 3A SMPS to power the board and the Pi from 12v line.
- Compatible with OpenCPN, OpenPlotter, Signal K and CANBoat
So besides NMEA 2000 and 0183, you can also connect other I2C sensors if you'd like.
The biggest challenge with the board is going to be finding a proper case that has the right cutout.
Installing the board is straightforwards. Included in the package are four standoffs and screws which need to be attached to the Raspberry Pi. Then carefully slide the PICAN-M down the pins on the Raspberry Pi until it is well seated, and screw it down to the standoffs.
This is probably the only downside to this setup. The standard cases that come with the Raspberry Pi do not assume you will have an add-on or HAT board with it. Those that accommodate HATs are pretty specific, and have holes or punch outs for specific types of connectors. I have not found a NMEA 2000 specific case - perhaps an opportunity for 3d printing!
I found a case from HiFiBerry that was meant for an audio HAT and hacked holes in it to allow the NMEA 2000 port to be exposed. It's not great, but it works for now and keeps the boards reasonably safe.
Software & Usage
To do this, I simply connected the NMEA 2000 port to power up the Pi, plugged the included HDMI-mini to HDMI cable into a monitor, connected a keyboard, and followed the install instructions for OpenPlotter/OpenCPN. You can do this in an automated way, or even headless (without a monitor or keyboard) but it can get a bit fiddly if you make a mistake in the installation.
For Linux + Signal K, I used the standard Raspbian server minimal distribution and then installed Signal K afterwards.
The super nice thing is that the NMEA 2000 port just shows up as can0 to the operating system, so it is very easy to start using one of these applications to access the data on the NMEA 2000 network.
The absolute best part about this entire setup is the fact that the NMEA 2000 port is native, and that it powers the entire computer. No other cables or connections are required.
This opens up even more utility when considering what you could use this for. Besides running heavier applications like the above, you could use these in strategic places all around the boat to create an entire sensor network. Connect it to a NMEA 2000 tee somewhere, and have I2C or other sensors (Raspberry Pi have a wealth of different ways to connect various sensors) connected to tanks, temperature, momentary, etc. and run Signal K on each, spitting the data back to a central Pi or other computer to display things. The possibilities are actually quite exciting. I've tried to do this in the past with Arduino and other technologies, and it has been a bit of a mess with having to power them by battery or other conversions.
Cost & Conclusion
Overall this is a pretty inexpensive way of getting a boat computer on board:
- CanaKit Raspberry Pi 4 bundle - $114.99
- HiFiBerry HighPi case - $17.95
- PICAN-M HAT board - $94.95
- NMEA 2000 cable - $15
This is a very reasonable price, and is actually about the same cost as the Actisense NGT-1 USB to NMEA 2000 interface alone! For just under $250, you end up with a bus-powered, low power usage, reasonably powerful computer on your NMEA 2000 network.
You could buy a bare Raspberry Pi instead of one in a kit like I did and save some money, since you won't need a power supply or the case it comes with. You could throw in a 7" touch screen, similar to what I did on Grace's navigation panel, and have a complete computer setup that you could interact with like a chart plotter, all powered by the NMEA 2000 bus connection.
I think this is a fantastic way to get Signal K on board your boat in a single hardware device, all powered by the NMEA 2000 network. It's also a great way to add OpenCPN or OpenPlotter if you don't have a good navigation / boat management tool already on board. It's well made, easy to put together, and opens up the possibility of having access to boat data for those not interested in the more DIY approach. If you have a NMEA 2000 network, and don't have Signal K installed, this is a perfect way to do it.