Navigation and Integrated Electronics

Before purchasing a boat, electronic devices were upgrades we were hoping to minimize. Full packages of devices are incredibly expensive, go out of date quickly, and have vendor lock in. Many make due with simply a tablet for navigation/ back up charts, the feel of the wind on their faces for direction, and possibly a windvane for self steering. For easy conditions (small waves, low wind, no fog) this is fine and often preferred. But often we’ve had to sail in difficult conditions, and nearly every bit of information and help is worth paying for. Integrated electronics are of course not necessary, but we see them as insurance, and one extra thing we can do to prepare.

It’s also just fun.

Which Vendor

The industry is consolidating and the main options are Garmin, Navico Group (who owns Simrad Yachting, Lowrance, B&G), Raymarine, Furuno. Once you choose one you’re mostly locked in, and they all have different strengths. Garmin integrates well with their endless products, Furuno still has the best Radar technology, and Navico owns a lot of the brands and is a bit more open with their standards. Our boat came with Garmin, and the experience is fine — though clunky and expensive.

Another option is to roll your own electronics system and use open source solutions like OpenCPN, SignalK, or OpenPlotter. Using most of these is a pretty horrible experience, but the functionality is all there for most anything you can think of (radar, autopilot, instruments). For small instruments, most devices will run on “Nema 2000”, which means data can be shared outside the vendor. This is how devices communicate with each other even within a vendor ecosystem, and it’s easy to tap into and extend. This works for things not transmitting a lot of data (wind instruments, AIS, depth) but for devices that need to transmit a lot of data, or things which the vendor wants to lock down (radar, autopilot, sonar), the data is proprietary unless it’s been reversed engineered.

In our boat we’re trying to go the open source route as much as possible, but also have a full Garmin system as backup. Both systems run at the same time, using the strengths of each and adding redundancy. The Garmin setup is missing some functionality over devices we’ve chosen that won’t integrate (most notably radar), but most things still communicate over Nema 2000 and can be generic. Long term we hope to move away from Garmin entirely, but that will be many years.

Boat Server/ Multifunction Display

The heart of all these systems is the “MFD”. It’s normally a touchscreen linux computer which can stand up to the elements, and acts as the brains of the entire ecosystem. You normally want at least 1 below deck, and 1 - 2 (radar and chart plotting for example) above deck. They are incredibly expensive for what they are, and the main place the vendors try to lock you in.

On our boat we have one Garmin MFD below deck, and have added a second “headless” linux boat server to run all our open source software. These both tap into the same Nema 2000 Network, and the “headless” boat server forwards information to our phones and tablets while sailing. At some point we might feed the open source data to a marine touchscreen (can be had for ~$150), but for now appreciate the flexibility of switching between mobile devices as needed. The less devices permanently mounted outside in the sun, the better.

For the boat server, there are many options to consider. Any computer will work, but the environment inside a boat is very rough with humidity and temperature fluctuations, dealing with surge power and fluctuating voltages, and power draw considerations. We’ve opted to go with a “Raspberry Pi Compute Module 5” based solution, even though the performance per watt is not great, and the Raspberry Pi 4 likely provides all the power we would need. This server is used for other purposes on the boat as well, and the ability to add additional “hats” and customize for whatever we need, made the flexibility worth the energy consumption hit. Other options might be a mac mini (though you’ll need to figure out DC power and protect from voltage fluctuations) or an Intel NCU.

After deciding on your computer, you then need to figure out how to get Nema 2000 information actually into it. You can either do this by plugging directly in the server via USB (yatch devices, Actisense) or you can expose Nema 2000 over wifi (yatch devices, digital yatch, hat labs). These are all quite expensive, and if you would like to DIY a solution, look here. Between these two options, wifi is easier to setup and more flexible.

For us, we ultimately decided to go with a prebuilt package from “Hatlabs” called the HALPI2 that accepts/ is powered by Nema 2000 input. We could have built something ourselves for a little cheaper, but for $370 (8gb ram and 512 GB SD), the price was reasonable. We’ve fried servers on our boat due to humidity, and the fact that he has open sourced the firmware (written with rust and embassy), open sourced the PCB files, and done months of stress testing/ considered thermals of the case so extensively, made it an easy buy. So far no issues, but of course, it is a product suited to DIY so no guarantees.

Chart Plotting/ Radar Sensors

Currently we run OpenCPN and Garmin Navionics (previously independent, now bought by Garmin with a big price increase). Like many of the open source solutions, OpenCPN is functional, but is a really clunky experience. It also will probably never be as up to date as Navionics, and the routing algorithms and such are absent or not very good. There are many chart plotters that run on tablets, but we use Navionics specifically because it was previously the most famous, and allows for overlaying AIS targets (ship names and locations) the easiest on the charts due to our Garmin system. We mainly use OpenCPN to view radar independently, and this is streamed via VNC or NoMachine to our IOS tablets. OpenCPN runs natively on Android (thought not IOS), but the specific radar plugin can’t run on Android, so we still need to stream the data instead of run on the tablet.

Another option is something like Orca. Orca is a Chart Plotter that tries to differentiate by providing the “Orca Core” and “Orca Display”. The Orca Display is simply an Android tablet that runs their chart plotting software, and is cheaper and more flexible than purchasing a “MFD”. The processing for the chart plotter happens on this device, instead of being streamed over wifi. Orca Core is just a linux computer, that has a “satellite compass” and “9-axis” gyroscope built in. This gives it the information it needs to control radar and autopilot and does stream over wifi. It acts exactly as our “Pi Based” boat server in taking in Nema 2000 information, but streams that to it’s proprietary software instead of open source. They don’t use a true “satellite compass” however (more on these below), but it should be fine for most situations.

Radar Hardware

As stated before, we can easily get most of the information we need for radar from additions to our linux server. Radar will still work fine without this information, but won’t be as good and will lack ARPA/MARPA. Currently we haven’t gotten around to adding this, and simply view the normal data through OpenCPN with AIS targets overlaid on top to see what is a ship.

If you would like to use Radar with OpenCPN or other open source hardware (or even Orca), be sure to buy devices from Raymarine or Simrad. They don’t have an “open” protocol, but they also don’t lock down/ encrypt traffic and can thus be reverse engineered and controlled. For current radar support with OpenCPN and most likely Orca, look here. We use the Simrad “Halo 20+”.

Auto Pilot

For auto pilot you can use most any of them with OpenCPN, or build your own with pypilot. The “pypilot” system is enticing because most of these systems are again, very over priced for the components that they are using, and it’s nice to have control. We don’t yet have a tiller pilot, but we’re planning on using Pelagic as they have already spent the time tuning it. Eventually we hope to make our own, or at least buy new actuators online directly instead of using pelagic replacements.

Satellite Compass

A “Satellite Compass” is a device that uses 1 or more “Global Navigation Satellite System” (GNSS) antennas, and measures how long a satellite signal takes to reach each antenna to determine heading and location. This is then used to improve autopilot, and enable technologies like “ARPA/MAPRA” on radar. Due to the hardware required, they are quite expensive.

As mentioned before, another option is something like what’s found in the Orca Core 2. This is a single GNSS antenna, with a motion processor and “rate of turn” compass. The hardware is much less accurate, but it compensates with a higher refresh rate, and using algorithms to approximate everything. The specs they quote are comparable to a real satellite compass, but this is only under ideal conditions when the boat is moving a couple knots. If the boat is stationary (ie fishing), or heavy seas, the ARPA/MARPA experience wil be much worse than a real satellite compass.

Currently we use a basic GPS compass, and live with the less accurate radar.

AIS

AIS communicates over VHF radio, and sends/ receives boats location, heading, speed, and other boat data. It then allows for seeing other boats information directly on the chart plotter, or radar. To use this technology, you must install a “AIS Receiver”, which must have it’s own dedicated GPS antenna. Most things on the boat share information via NEMA 2000, but in order to be compliant, and AIS Receiver must use it’s own GPS antenna. For these reason we have two GPS antennas aboard (one in the AIS receiver, one dedicated).

VHF

A VHF radio obviously allows you to communicate with other boats over radio waves. Modern VHF radios can also receive (though not transmit) AIS information, and call other boats through “Digital Selective Calling” (DSC). To use DSC, radios send data over channel 70, which will then switch the other boat to the proper channel in order to speak. They also have emergency features will broadcast to everyone who has radios on, instead of needing to communicate over channel 16.

We have one radio below that’s hooked into the antenna on the mast, and then carry a small hand held radio for calling people while in the cockpit. Originally we tried to just use the radio below, but with the engine running it’s hard to hear, and in emergencies close to shore it’s nice to not leave the cockpit. We plan to upgrade to a permanently mounted cockpit radio, so that we can use the mast antenna for greater range.