Saturday, 24 November 2018

A Raspberry Pi running OpenCPN

While having an afternoon coffee on a neighbors boat I noticed a small printed circuit board connected by HDMI cable to the monitor/TV on the bulkhead. I was intrigued, what is that board? I asked. At first glance I thought it was a video casting device, TV tuner or power adapter of some sort. Turning it on he explained it was a Raspberry Pi running OpenCPN and was a very powerful small computer. He had been using this one or previous models as a navigation aid running OpenCPN for a year or two and he was very happy with its performance.

Raspberry Pi in its case running OpenCPN which is part of the OpenPlotter install package

Later in the afternoon we did passage planning using OpenCPN running on the Raspberry Pi.  I didn’t notice any performance issues and was most impressed with this micro sized computer.  We looked over anchorages zooming in and out, making routes and updating waypoints. We revisited anchorages we had used when we had explored the areas he and his wife were about to travel to and I must say I that if I didn’t know OpenCPN wasn’t being run on a laptop I would not have been any the wiser. We also down loaded some layers containing our old tracks and routes, and added some .KAP files to his electronic chart directories. All these worked just like OpenCPN we use on our laptop. 

Unfortunately we didn’t get time to talk more about the Raspberry Pi. We had an early night as we had to leave the next morning early to catch the tide. Then getting busy with our own passages I didn’t really give the Raspberry Pi another thought for several months until I was updating OpenCPN and saw the link for the Raspberry Pi software.
https://opencpn.org/

I did a little research and not surprisingly found there is a large community of sailors using these small powerful computers to handle a vast range of tasks on board.

We run a laptop with open-source OpenCPN navigation software and it does have some nice features, written by sailors for sailors. The laptop works fine as does the OpenCPN software. Like most electronics they have a limited life span and our laptop is getting long in the tooth and it always sits in the middle of the chart table on passage which can be annoying. It would be nice to have a built in integrated system networked to the rest of the boat. Until recently we would have to plug in the serial to USB converters to supply the OpenCPN with GPS and AIS data. After installing a small Wi-Fi access point to send the serial data streams to OpenCPN on the laptop we found it was a lot easier to use. While this is good we still need to supply power via cable to the laptop.
OpenPlotter remote desktop display on the mobile phone.

We think it is time for an upgrade. So for our next system we would like a low cost option while having a big range of features reserved for the more expensive chart plotters. You know things like Wi-Fi connect ability, data quality analysis, the ability for remote desk tops, and an access point for sharing the navigation data with smartphones and tablets.

So following the lead of the large community of sailors using Raspberry Pi’s I have started to build my next chart plotter using one as a core. As I have said before Raspberry Pi is a low cost, low power consumption computer when compared to a standard laptop, or chart plotter. An added benefit is that additional boards and sensors don’t cost a lot either. If you have a trailer sailor and want a chart plotter with big features that won’t bleed your battery(s) or wallet dry this may be something to look into. There are several display/monitor options for the RPI that should work on the trailer sailor that wont require massive power reserves.
Running a comparison between OpenPlotter rear screen with our trusty laptop looking very good.
So I had a couple of decisions to make, should I buy a Raspberry Pi and just install OpenCPN and use it as a bare bones unit. Or should I start from scratch and build an integrated system. I decided the build from scratch would be way too time consuming. The reality is I cannot really remember the last time I used UNIX with purpose or wrote code, and I wanted a chart plotter this century. I know I could have and was prepared to use some of the shared code offered on several web sites. Unfortunately upgraded operating systems could mean this shared code was no longer valid.

So after reading a quote from the author on a site I had been following with interest as he built a system from scratch, “well that’s it for me I am going to use OpenPlotter”. 
OpenPlotter install running on a Raspberry Pi

So what is OpenPlotter? After some more research I found out that it’s a combination of software and hardware to be used as a navigational aid on small and medium boats. It is also the hub of an on board vessel automation system. It runs on the Raspberry Pi and is open-source. The design is modular, so once you have the core system up and running you can start to implement what your boat needs. For lists of the current OpenPlotter software features visit.  http://www.sailoog.com/openplotter/


Click this link to see what we did and how we did it.

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