A 15" Touchscreen Chartplotter for around $500?

 First a belated Merry Christmas and Happy New Year everyone!

My boat came with a Garmin 4208 chartplotter.  Unfortunately, the prior owner(s) did quite a hack job installing it and, as a result, there was a rather large and unsightly open hole in the hull behind the unit.  This hole prevented me from ever removing the chartplotter from the helm as it was the rain shield.  Well, a chartplotter is an expensive umbrella, and after having spent many years acting as such, it began having some issues.  The case seal had failed and allowed moisture to enter. Best I can tell, this caused a light film of mold to start growing in the screen and was slowly making it unreadable.  It was time to find a solution.

The Old Garmin Plotter,
as installed by prior owner

I could have bought Garmin's current replacement unit for around $3000, and would have the same functionality that I had.  There were a couple problems with this.  Since my depth, wind, and autopilot are Raymarine, they did not like talking to the Garmin.  Being from the aviation world, I'm also not a big fan of Garmin (particularly after they charged me over $150 for a 32 MB data card while standard 1GB SD cards were selling for around $20).  While talking with the harbormaster at my new marina, he was telling me about Openplotter and how he and others had built their own chartplotters using a Raspberry Pi computer and a few other inexpensive electronic bits.

Who cuts a hole like this?

Fixed, with a mount and connectors
for the new touchscreen

I did some research and decided that it would be worth the effort to try and build my own chartplotter using Openplotter.  If successful, I would have a nice chartplotter that would be capable of integrating the information from the Garmin radar, Garmin sonar, Raymarine wind, Raymarine depth, and Raymarine autopilot without having to replace all of this equipment with items from the same maker.  I could also add a 15" touchscreen interface, AIS receive functionality and, the best part, this would cost me only a fraction of the cost of a complete solution from any of the big name marine electronic manufacturers (a 16" Garmin package would likely run over $7000 by the time all was said and done).

So, for this experiment, I purchased the following:

• A Raspberry Pi 4 w/4GB memory, case, data card, fan, and card reader $125
• 15" touchscreen display $120
• Outdoor VESA mount for monitor $23
• 3 64 GB micro SD cards for programming and backup $20
• 12v powered USB hub (for connecting and powering peripherals $20
• A USB GPS antenna that outputs NMEA sentences $20
• A Berry IMU gyroscope/compass/acceloremeter chip $38
• USB RS485/422 converter (for NMEA output) $18
• RTL-SDR Radio (for AIS receive) $33
• VHF whip antenna (for AIS receive) $10
• Opticoupler (for SeaTalk input) $8
• 2 128GB USB flash drives (for chart/data storage) $25
• 12v to 5v USBC power supply $12
• Various cables, connectors, fuses $80

Installing the OpenPlotter software package is pretty easy.  You download the Openplotter image for Raspberry Pi and use an imaging tool to copy it to the micro SD card.  You then insert the MicroSD card into the Pi, hook up the monitor and boot it up.  In order to program and modify things, I also used a Bluetooth keyboard that I was able to add once the Pi booted up.  Then the fun really started.

A touchscreen at the helm
(had to add an anti-glare screen protector)

I won't go into all the details on how to setup OpenPlotter as there is a fair amount of information out there already and it all depends on what sensors and equipment you are trying to connect.  I actually started work on this at home, and overall it took me several months worth of occasional tinkering plus the actual installation on the boat.  But, if you are considering taking on a project like this, I do have a one bit of advice.  Buy a couple spare memory cards for the Raspberry Pi.  You will want them to make backups.  I would suggest keeping two different backups, one for every major milestone and another for more often created backups.  This way you will have options for going back to two points without having to start over.  There were a couple times during my work where a bug was introduced but not noticed until several changes later.  If I didn't have the major milestone backup, I would have been unable to back up to the point before the bug was introduced.

Another thing I didn't realize was that the Raspberry Pi, at least at the time of writing this, does not support the equivalent of a "right click" for touchscreens (either a long-press or double tap).  Since OpenCPN is difficult to use without the right click, I had to find a solution.  I found there is a software driver called Twofing that converts a two fingered tap into a right click.  I installed and configured this driver and was able to right click on things by tapping two fingers on the screen on either side of the item I wanted to right-click on.

I setup the Raspberry Pi to automatically start OpenCPN on boot such that it takes up about 75% of the screen real-estate and another package called Kip to display the information I wanted and is typical of a chartplotter on the other 25%.  The Kip package is actually a configurable web page and can display basic numeric and text data, graphs and gauges, and has a nice compass rose that can display wind speed, direction, laylines, and direction to your next waypoint all on a single dial.  It can display any data that is collected by the system.

Plotter interface in Day mode

...and in night mode

I've still got a little work to do, but so far I am very happy with the results.  The Raspberry Pi gets position information from the USB GPS receiver, wind and depth information from the Raymarine Seatalk connection, AIS information from the RTL-SDR card.  An OpenCPN plugin supports the Garmin HD radar and utilizes free NOAA digital charts and even Explorer charts for the Bahamas (and other areas) from O-charts.  Routes are finally able to be output via NMEA 0183 to the Raymarine autopilot, and I even have pitch and heel information from the IMU. Using a GRIB file downloader, I can load and display weather forecast information overlayed on OpenCPN charts. I can also connect wirelessly to the Raspberry Pi and monitor the boat using my cell phone or a tablet.  And one more added bonus, with the 128GB memory stick, I not only have enough storage for charts, but can also use it as a media server/player...so much of my music collection can be streamed to my Bluetooth enabled stereo. 

The two items supported by the old Garmin that I don't have working are the XM radio and the Garmin sonar.  Although I haven't removed the XM unit, I've never used it and thus far I don't have any intention of using it.  I am unaware of any existing support for the sonar and when I have more time will look at writing a plugin or app to interface and decode the data sent from it (I do see the sonar data on the Pi, just don't know what to do with it yet).  I should be able to at least get depth information from it, if not a full sonar image with fish detection, etc.

The one thing I may change is the touchscreen I am using.  Since this was essentially an experiment, I didn't want to throw too much money into it without knowing how well it was going to work.  I thought the screen I chose would be bright enough to be daylight readable, but I didn't take into account all the reflected glare onto a shiny touchscreen.  The first time I tested it with the sun behind me, the shiny surface made a better mirror than display.  I added an anti-glare screen protector that has helped a lot, but would also like if the screen was brighter.  I know there are brighter screens out there, but they will increase the price of this project a bit.

I will say that, if you are not comfortable with computers and soldering and playing with electronic internals, this project may not be for you.  There is a lot of fiddling with hardware and configuring software involved.  There is nothing that is too complex (except for possibly the sonar, I didn't write any code beyond the script to automatically start the interface the way I wanted it), but there are a lot of individual pieces that need to be setup to work together.  If you are comfortable with these tasks, you can make yourself a very capable chartplotter using well developed and free open-source software.

A Couple of Projects

 Well, if you have read through my blog, you probably have a good idea of the amount of maintenance required to keep a boat going.  And this post will be no exception.  It still amazes me how many new issues appear when you leave a boat sitting for even a short period of time.  So, upon returning to the boat I had a list of minor things to address (for example, some running rigging needed to be replaced and some leaks needed to be addressed) and a couple of bigger projects.

The first project was the inverter.  As I mentioned in my previous post, my old Xantrex Freedom Marine inverter decided to give up during our spring shakedown cruise.  I pulled the unit and did some troubleshooting and found a blown internal fuse.  I tried replacing it, however the fuse immediately blew when attempting to start it up...so something in the internal circuitry has obviously failed.  I guess I could try repairing the unit, but it is 30+ years old and there are newer options out there that provide pure sine wave output and are more efficient.  It made the most sense to replace.  Of course, I don't want to rewire the boat, so in addition to finding newer technology, I needed to find one that would fit in the available space.

I narrowed my search down to two or three options that would fit, were at least theoretically suitable for the marine environment, and would provide pure sine wave output.  Two of the options could be found listed on marine supplier websites with prices north of $1500.  The third option was from Renogy, a company that is more well known for solar and off-grid land based setups, but claimed their unit was marinized and could handle the more corrosive environment found on a boat.  The fact that their unit was also 1/2 to 1/3 the price of the others, I decided I would give it a try.

Renogy 3000w pure sine wave inverter
(Image from Renogy.com)

The unit was a bit longer than my old one, fortunately, that was the one dimension where I had a bit of extra space.  Otherwise, it was a direct replacement as it specified the same gauge battery cables and fuses and was a mostly drop-in replacement.  Wiring was pretty straight forward, and other than finding and replacing a poorly crimped cable end on one of my cables, the unit itself wasn't too difficult to install.  The unit comes with a remote panel, but unlike the Xantrex, it is not very informative, just a switch with a couple of status LEDs.  A remote that mimics the on-board display would be a better option, and hopefully they will consider making one.  The remote was also smaller than the Xantrex, so I had to custom fabricate a plate to mount the new remote where the old one was.  Fortunately, this was easy to accomplish by purchasing a 3-gang black switch plate from the local hardware store and making a few modifications.

Other than the remote display and a couple minor quirks, so far I really like the unit.  Unlike the Xantrex, it has a very clean, pure sine wave output. Things like my induction plate and microwave are happier about the supplied power.  It also switches over to inverter power much faster than the Xantrex, so the microwave clock doesn't need to be reset and the TV doesn't even flicker.  The most annoying thing about it is that the battery charger cannot be disabled when the unit is on and the AC circuits downstream of the inverter are not active in bypass mode when the inverter is off.  These are minor issues and easy to work-around, but would be nice features to add.  Given I could buy 2 or 3 of these for the price of the others, to me it is a worthwhile tradeoff.

Another bigger project is replacement of my old chartplotter.  The main reason for its demise is that the prior owner of the boat did quite a hack job when installing that resulted in a large hole behind it and so I never removed it from the helm.  I could possibly replace just the screen and maybe the seals that caused the current problem with the unit, but just like the inverter, the entire unit is older and I suspect other internals are likely soon to have problems as well.  I could buy a new unit from Garmin that would be mostly a drop in replacement with the same 8" display, but that will set me back about $2k...not to mention I'm not a huge fan of Garmin.  

The other option to replace the chartplotter is to essentially build my own.  There are a couple of open-source software packages out there that are capable of replacing an existing chartplotter and can better integrate most of my Garmin and Raymarine instruments.  For the cost of a Raspberry Pi computer, a touchscreen display, and a few other electronic bits, I could have a more capable chartplotter than what I have now.  All that for what should come in at under $500 and some of my time.

Openplotter running on my Raspberry Pi.

I decided to go this route and have been working on the solution for a little while.  I'm using OpenPlotter, which includes the OpenCPN chartplotter software, SignalK for data integration, and a variety of interfaces to deal with a variety of instrument data.  Above is a picture of my working system on a 15" touchscreen display that is temporarily hooked up to my boat instruments.  You can see current wind, depth, location, direction, speed, pitch and roll information.  You can even see the AIS data from a few nearby boats in the marina.  Not displayed but working is the radar information and overlay.  Since the computer isn't mounted yet, the sensors aren't fully calibrated so some of the information like pitch and roll are a bit off...but it is sufficient for proof of concept.  And for the first time since I've owned the boat, I can now send route data to the autopilot.  The only thing I haven't figured out yet is how to get more detailed sonar information as Openplotter doesn't seem to have a means of supporting a fish-finder type of sonar.  This solution will also be setup so I can easily detach the display and store it inside.

The final bigger project I'm working on is my refrigerator.  Over the past several years it had started developing an issue where the compressor made multiple attempts before it successfully started.  Originally, this was infrequent, but more recently it has happened with increasing frequency to the point that it was no longer reliable.  While looking into the issue I noted that the compressor was rather old and had significant surface corrosion.  Apparently the original controller had failed at some point and was jury-rigged with one from Alder Barbour.  So, my best guess is that either the controller or the compressor was the likely the current issue...of course, that makes up the vast majority of the system.  As a reliable refrigerator is necessary for any longer trip, I decided to bite the bullet and replace the whole system.  New systems have more efficient compressors and often come pre-charged so at least I won't need a refrigeration technician to come install it.

Seafrost BDxp Refrigerator system
(image from Seafrost)

The original system was from SeaFrost. Not wanting to significantly alter the setup, I decided to go with them again.  After talking with someone from SeaFrost (I think it may have been the owner), I decided to get the upgraded version with a bit higher capacity.  The belief is that it should be sufficient to store ice cream (something that was just a bit beyond the ability of the old system).  The old setup of the refrigerator is what is known as a spillover system.  Some of the cold of the freezer "spills over" into the refrigerator side through some holes to provide refrigeration.  While this does work, it does have some drawbacks.  There was a tendency for items at the bottom of the refrigerator section to freeze while the top was barely within the safe zone for a refrigerator.  With the increased capacity of the new system, I think this issue might become worse.  So, I also intend to alter the spillover system by adding a duct, small fan, and temperature control in hopes that it will better meter the temperature of the refrigerator as well as provide a bit of air circulation to keep the temperatures a bit more uniform.  

So, those are the bigger projects currently going on or completed.  Hopefully they all will be done soon and I can head south and to the Bahamas.

What's Shakin'

Oops...thought I had published this months ago...so this is a bit behind... 

Well, this last trip back to the boat can best be described as shaken.  My intention was to take at least a shakedown cruise, but other things also shook things up a bit.

One shakeup was that my friend TJ from the Retirement Project had what was described as a "cardiac event".  In hindsight it was a good thing that it took longer to get their outboard fixed and they were still in Oriental when this occurred as he was able to get the medical attention he needed quickly.  After a short time in the hospital in New Bern, I'm happy to report he is doing better now.  Unfortunately it has altered their plans for the Great Loop, but ever changing plans seems to be the norm for cruising.  I was glad to be able to provide some help and support for such a lovely couple and am glad TJ is getting back to being himself.  Stay well my friends and let us know if we can do anything for you....either here or when we are back at the boat.

A variety of things were fixed or worked on while at the boat.  The house battery bank was replaced.  The old chartplotter seems to have developed a screen issue and, instead of replacing the screen or the unit, I've decided to try building my own chartplotter using Openplotter.  If successful, this system will have a 15 inch touchscreen display at the helm, provide AIS receive functionality so I can identify nearby boats, and finally integrate all the systems so the Garmin radar and sonar and Raymarine winds and depth instruments can all talk to one another and the autopilot.  All at a fraction of the cost of an existing commercial unit. I'll (hopefully) write more on this later.

We did get a chance to take a shakedown cruise.  It was a relatively short trip from New Bern to the Cape Lookout bight.  We anchored there for several days, enjoying the area and testing systems.  

Of course, as a shakedown cruise, we tested several systems.  Unfortunately, while trying to make some ice for drinks one evening, the inverter suddenly died.  The inverter isn't a critical piece of equipment, but it is nice to be able to run standard AC electrical items, particularly if you want some ice for your evening adult beverage.  So this is another item that will need some attention.  Since it is an older inverter, it might be time for a replacement, we will see.

So, we managed a shakedown run, we shook things, and something broke.  But that is about par for the course on a boat.  Guess I have a bit more work to do before the Bahamas trip in the fall.