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Old 28-08-2018, 11:02   #1
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DIY Boat instruments

After a bunch of work, wanted to show off what I did a bit

My boat (an older Beneteau First 375) came with some very old instruments when I bought her. Mostly they worked, but the GPS was flaky, and the masthead anemometer was defective. While not particularly needed, Iím a geek at heart and love new technology, and so wanted to upgrade to some newer instruments. Like Iím sure many have done before me, I priced out a brand new NMEA2000 based system including the sensors, Instrument displays/MFD and a chart plotter. The sticker shock was palatable. I didnít even bother asking the Admiral (my wife) for the moneyÖ

Open Source/SignalK

Around that time I came across a post on a forum mentioning the OpenPlotter project. Having played with electronics back in my youth I found it pretty inspiring. I got my first ever Raspberry Pi, and played around with it on my workbench. OpenPlotter introduced me to a bunch of stuff that could be done in the DIY world, and it was here that I first learned of Signal K.

Signal K is an open source data format to represent and communicate boat data, much like NMEA2000. Rather than cryptic often poorly documented PGN messages, Itís based on JSON and other standard web technologies like HTTP and Websockets. The Signal K project has worked to create a specification so that boat data can be viewed in a consistent way across boats and applications (much as NMEA2000 does). It provides a nice easy to use standard.

Design goals

My first step was to try and define exactly what I wanted to achieve. My first goal was to replace my instruments. Three old Raymarine ST60 instruments (Wind/Depth/Speed) along with an old Raymarine c80 chart plotter. My other main goal was to be able to ďmonitor all the thingsĒ. Iíd love to know more about the state of my aging engine, fridge temperature, AC/DC systems, and more. Commercial solutions though are almost always expensive.

My final goal (and a big one) is that I didnít want to hurt the boats resale value. While I love this kind of stuff, if ever I needed to sell the boat many/most potential buyers would see DIY electronics as a negative.

Bringing it together:


Dealing with resale value first, I decided that I would not DIY the ďmainĒ sensors, mainly Depth/Wind/Speed. I had thought about re-using my existing depth and speed transducers (wind was broken), but they were meant to connect directly to the ST60 instruments at the helm. I could have possibly DIYed something, however updating these with retail sensors and a new NMEA2000 backbone means that if want to sell the boat, I already have a NMEA2000 network that I can easily slap a new chartplotter/MFD on. To this end I bought a B&G Wind sensor, a DST800 through hull combined speed and depth sensor, and a NMEA2000 starter kit. I also connected my existing VHF (B&G v50) to this new NMEA2000 network for AIS information.

In order to get the NMEA2000 data into Signal K format I had a few options. Many people seem to be using the Actisense NGT-1 NMEA2000 to USB adapter with great success. Others have been using other homemade interfaces. In the end I decided I wanted to support companies getting behind Signal K, so I picked up an iKommunicate from Digital Yacht ( An additional consideration that helped me pick the iKommunicate, is that should my own Signal K server fail or be miss-configured, the iKommunicate itself is a Signal K server and could be used stand-alone. (You can open an app hosted on the iKommunicate and see the NMEA2000 data directly)
Signal K

Next I needed a new Ethernet network to connect the devices together. While thereís many great residential Wifi/Switch/Router combos out there, I didnít want to have to use an inverter to power them. Most are hard to find the voltage for online before ordering, and even if theyíre 12V, itís hard to know if they would tolerate the fluctuations in boatís power (11V-15V). However I then discovered the term ďTravel routerĒ. These usually run off of USB (5v) and have friendly interfaces to configure them in WISP mode. (Allowing you to connect the travel router to the marinaís Wi-Fi and give connectivity to devices connected to it if needed.) I also wanted something that would support VPNs so that I could remotely reach and monitor the boat. I ended up getting a GL-AR750 router, that after a bit of fiddling, seems to be working fine. I donít know if I would buy it again though.

Powering the core of the setup is a Raspberry Pi 3. While Openplotter is a great project and Iím following what theyíre doing closely, for my particular setup I decided to just run a simple Raspbian OS install. It runs the Signal K server, as well as using InfluxDB database and Grafana graphing application for historical data. Connected to the Raspberry Pi server via a serial connection is an Adafruit Ultimate GPS module. This provides GPS position/speed etc as well as a time reference. Finally I connected up the iKommunicate to the net ethernet network to get the boat data into Signal K. I mounted all these compontents to a small peice of wood. I leave all that powered on 24/7 as it does not take much power at all surprisingly.

At this point I had my server and data in my server. For easy visibility of the data while below I also added a second Raspberry Pi with their official touchscreen. I mounted it in the cabin so that I can easily see all the data from within the boat. In addition any phone or tablet can connect to the wifi and view the data on the server.

Helm Displays

One decision I had made is that I wanted a larger screen in the middle of the helm, and two smaller screens on each side for instruments. I also wanted at least the smaller screens to be on mounts that could swivel to have them face forward. Often I find myself forwards of the helm, either on autopilot or just sitting on the high side if weíre heeled over. Being able to rotate them allows me to see the data no matter where I am in the cockpit.

I must say that finding a waterproof, sunlight readable, touchscreen display that didnít cost $4000+ was like trying to find a flying unicorn. In all seriousness if someone is looking for a business idea, this may be a niche market but there seems to be plenty of opportunity if you can make it work! To reduce months of researching and reading to a few sentences, I found two companies that had displays that seemed to fit the bill.

For the larger center display, I went with faytech ( They have a range of IP65 high brightness screens that are at a reasonable price point. (You can see prices on their US store). I ended up with the 12Ē Capacitive model for the multi-touch capability. For the two smaller displays I went with Argonautís M7 7Ē Capacitive touchscreen. ( They were a bit more expensive than faytechís 7Ē model, but I wanted the capacitive multi-touch. (Seems their price went up since I bought mine though)

Both models of display are plenty bright for direct sun and look great. My one big complaint with the faytech monitor is that its brightness setting does not go low enough to be useful for night sailing. It goes low enough that it wonít hurt your eyes, (so like watching a movie at anchor is ok) but your night vision will be ruined. The M7ís go so low that you can barely tell that theyíre on. Only other complaint about the faytech is that the buttons on that model were on the back, so you cannot flush mount it in a navpod or something as you wouldnít be able to reach them (that was my original plan for that one)

To mount them I ended up using Ram mounts for all three monitors. They mount to the guard rail of my pedestal, and are easy enough to position how I want. One consideration that complicates things a bit is I wanted the monitors to be easily removable. Both for future winter storage and for theft concerns I store them below decks (my marina is in the city, would be easy to go up to monitor, cut cables and walk off with it). To do this I passed some HDMI and USB extension cables from below deck through a watertight fitting. I can connect the monitors to those extension cables however the cable connections themselves are not watertight. Until I can think of something better I am putting them inside a waterproof bag, folded over itself so water would need to fight gravity to get in. Given that Iím sailing in freshwater, this may do.


Finally, to power the three monitors I was originally going to use three raspberry Piís, one for each monitor. However I decided in the end that I wanted something else. My main criteria became an x86 processor and support for 3 monitors. With an x86 processor I would have the option to run Windows 10, or the more mainstream versions of Linux. x86 is just a lot more compatible than ARM, lots of software doesnít have pre-compiled ARM versions for example. Having support for three monitors on one board makes it a lot simpler too. Draging a window from one monitor to the other is great. Also running 3 Piís would mean 3 Piís to update, change configs on, etc.

I originally started looking at building my own custom pc from retail parts, but then I discovered the Udoo X86. It supports 3 monitors out of the box, uses little power, and has great specs for its intended use and price. (Quad core, 8gb ram, decent integrated graphics etc).

As for OS I ended up installing Windows 10 on the Udoo, and it runs great. I thought I would need a waterproof keyboard/mouse, but the touchscreen on the 3 monitors is great and Iím finding the Windows 10 ďOn screen keyboardĒ is enough for my needs. Of note though that Windows tablet mode which I had hopped to take advantage of does not work on multi-monitor setups.

For chartplotting I installed OpenCPN, and for the instruments I ended up writing a web application called Kip to stream and display the Signal K data. That said itís a normal version of Windows the options for software are many.

More Data! ESP8266 Wifi Sensors

Along the way someone told me about the ESP8266 microcontroller. For those that donít know itís an Arduino compatible microcontroller that supports Wifi, and has more RAM/processing power that most other Arduinos, and is pretty cheap (under $10 shipped). As of right now Iíve installed two. First one is a heading sensor which gives me heading, roll, pitch and barometric pressure, and the other is a DC monitoring sensor giving me Voltage and Amps of my house bank. I used 3d printed a case for them.

Planned next are a chain counter for the windlass, Fridge monitoring (temperature/compressor runtime), Bilge monitor, Engine Monitor, Rudder reference, and an AC sensors. I'll likely think of a few more as I go as well These may be more of a winter project though, the season is almost over and I'd rather sail for now :P


Excluding the price of the NMEA2000 sensors which I would have had to buy anyways, I spent a bit over $2600USD for my Signal K setup.. I figure a comparable retail system would be 3x 4Ē NMEA2000 displays for instruments, and a 12Ē Chartplotter. At $500 each for the instruments ($1500) and another $2-4K for a 12Ē chartplotter, I figure Iím ahead a few thousand dollars at least, especially if you start adding on the other sensors (heading/GPS/motor/etc).

More importantly than price though, itís been great fun getting this system going and Iím really proud of it. Since nothing is locked into proprietary products, Iím free to do what I want with the system and the data it contains. I log all the data, and can review it easily afterwards. I can see on my phone via wifi what the wind speed is without getting out of bed at 2am. I also donít need to worry if the chartplotter Iím spending thousands on will be supported in 2 years.

Safety Disclaimer: I sail on Lake Champlain, which has little to no navigational dangers. Iím never out of sight of land, water is deep, and the few obstructions are clearly marked and easily avoided. I can safely navigate to a safe harbor with 0 instruments (even GPS) should my DIY instruments fail. I also have paper charts on-board.


Prices in USD. They reflect what I paid at the time of purchase.

Furuno DST800 Through hull smart sensor: $294
B&G Wind Sensor: $458
Simrad NMEA2000 Micro C Network Starter Kit: $53
2 Lowrance NMEA2000 T Connectors: $34
Digital Yacht iKommunicate: $249
GL.iNet GL-AR750 Wifi Travel router: $45
2x Raspberry Pi 3 Model B: $77
2x SanDisk Ultra 32GB micro SD card (for Raspberry Piís): $36
Adafruit Ultimate GPS breakout board: $39
GPS Active Antenna: $18
Faytech 12Ē Capacitive IP65 High Brightness Display: $679
2x Argonaut M7 Touchscreen monitors: $892
Ram mount for 12Ē display: $130
2x Ram mounts for 7Ē display: $26
Udoo X86 Ultra with WIfi Kit: $307
Various HDMI/USB/Power cables: ~$100

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Old 28-08-2018, 11:10   #2
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Re: DIY Boat instruments

Thank you for the detailed post. I have been contemplating something similar, and was also stuck on the monitors. The Faytech monitors appear to be a good find.

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Old 28-08-2018, 11:36   #3
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Re: DIY Boat instruments

Excellent write-up, thank you for this! I have a Raspberry Pi doing nothing and this would be a great winter project to play around with. I also can't really justify a new set of instruments, even the most basic setup is $$$$.

If you had to do it again would you pass on the Faytech monitor due to nighttime viewing being too bright?
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Old 28-08-2018, 11:38   #4
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Re: DIY Boat instruments

Looks great

I think very few on here release just how powerful signalk is, data logging is gold dust. I'm using chronograf to view with a esp8266 code based on some of yours
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Old 28-08-2018, 11:40   #5
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Re: DIY Boat instruments

Originally Posted by tworail View Post
If you had to do it again would you pass on the Faytech monitor due to nighttime viewing being too bright?

If it was the only one I had it would be more of a concern, but I can just turn it off and use the two M7's. That said I'm on a small enough lake that I almost never sail at night.
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Old 28-08-2018, 11:54   #6
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Re: DIY Boat instruments

I would use another display with Android to add navionics maps and then you have the perfect setup
It can be done on the plotter screen using emulator .
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Old 28-08-2018, 13:52   #7
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Re: DIY Boat instruments

What a great, no compromise build!

The beautiful Kip web application that Tommy made, plus his work on the ESP devices, have been a great contributions to the Signal K community. I use and love Kip.

It should be noted that for those who wish to tinker with this with a smaller investment, much of this functionality can be achieved with a single raspberry pi running Openplotter, some inexpensive sensors, a direct-connected HDMI screen and a couple of tablets or phones accessing Kip in a browser.

I can't wait for Lake Champlain to freeze over so we can see what great things you come up with next!
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Old 29-08-2018, 14:17   #8
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Re: DIY Boat instruments

Can't get your display dim enough? Put this on at night.
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Old 30-08-2018, 01:27   #9
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Re: DIY Boat instruments

Good work, I love this DIY stuff and to see people being successful at having a go. Look forward to your future posts.
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Old 18-01-2019, 07:58   #10
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Re: DIY Boat instruments

i'll be watching this one closely. Thanks for sharing all your research and effort with us.
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Old 07-03-2019, 14:23   #11
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Re: DIY Boat instruments

Great post indeed. I am having a lil trouble setting up the ESP8266 to report to my iKommunicate SignalK Server. Did you need to setup security tokens for the ESP8266 to communicate with the iKommunicate SignalK Server?
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Old 08-03-2019, 04:40   #12
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Re: DIY Boat instruments

Greetings and welcome aboard the CF, JamesS.
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Old 08-03-2019, 06:46   #13
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Re: DIY Boat instruments

Excellent job creating your system and the displays are very nice. We took on a similar project to replace our outdated instruments on our boat.

Up to a couple of years ago, we weren't too tech savvy and had not even heard of a Raspberry Pi. Then our world changed by combining OpenCPN w/the Rpi. We were now able to use the OCPN to interface our Tacktick array and AIS in the nav station. Via wifi we were able to send all the info out to the cockpit and view it on a 11.5" W10 tablet.
We went w/OCPN, and didn't go w/the easier download of OPlotter since we didn't need all the additional bells/whistles. All that changed (again) when we needed to upgrade our 40 yr old autopilot. While it was cutting edge in its time and still used on many commercial fishing vessels, it was to large and clunky to today's standards. We found out OPlotter has an AP program built into it. With Sean's help (creator of PyPilot) to make a controller for our below deck hydraulic AP, we now have a hi-tech system that we can control everything in the cockpit.
To go from zero to somewhat techy is amazing and it works well. Took a bit to convince my wife that we didn't need to purchase a commercial system, but she has embraced it and is very happy with the performance.
If anyone is interested here are the links to the articles discussing the system on our boat.
Phoenix's Flight: Building a Marine Navigational Computer with OpenCPN and Raspberry Pi3
Phoenix's Flight: Pypilot Open-Source Marine Autopilot for Hydraulic Steering
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Old 08-03-2019, 07:14   #14
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Re: DIY Boat instruments

Love this thread.

Like many I have a few Raspberry Pi's kicking around (also some smaller Orange Pi H3 thingies)... and I adore the ESP8266... so this is all inspiring.

An inexpensive waterproof sunlight-readable display seems to be the grail. I have one mint display module (Epson?) and case from an older Lowrance chartplotter, but it's discrete RGB in (ribbon, not 3 or 4 coax inputs) and I haven't yet come across a way to drive it with a Pi.

I expect that a wireless tablet will be the preferred way to go, anyway... when/if I ever get to making a real instrument cluster. For most of our sailing to date, a Garmin handheld GPS and phone or tablet have sufficed.
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Old 08-03-2019, 07:24   #15
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Re: DIY Boat instruments

Great write ups, particularly the autopilot project. This is really paving the way!

I have a commercial Com-Nav system on my boat as well and it's good to know there is a viable upgrade path that won't cost as much as the boat. Plus I have a background in Unix administration and infrastructure so I really don't have any excuses

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