Signal K – open-source universal marine data exchange format | Hacker News Reader

Signal K – open-source universal marine data exchange format

signalk.org

82 pointspabs318 comments

A $30,000 car today often has a far better screen/user experience than a $300,000 boat. iPad/tablet apps for boaters attached to mounts are common, though lack communication with the boat's sensors (without something like Signal K), and are hard to see in full sun. Compound that with the Coast Guard being a defense agency where getting new data typres in and out is "a process."

Shameless but relevant plug -- I was annoyed hearing radio traffic of boaters trying to share their location with the Coast Guard, so I built a free tool for them (i911) that allows USCG to text the boater a link to share their location. The vast majority of distress calls are made within cell phone range (<15 miles from shore), so tapping that link isn't as much of an issue as you would think it is. It was the fastest tech to graduate from their R&D site to nationwide sector adoption.

https://www.youtube.com/watch?v=QF1pi2-ygXU

Excited to dig into Signal K to see if something there can help improve that response even further.

As someone with a boat, Signal K is super useful. It doesn't necessarily replace the other standards, but it means I can take my cats pajama's worth of other standards (NMEA0183, NMEA2000, homegrown Ethernet sensors) and ingest all of that data into one platform. After I've done that, it's really trivial to visualize it all in one place.

Given how terrible NMEA formats are, this is fantastic.

So this is an alternative to NMEA (which is a variant of CANbus / SAE J1939)?

* https://en.wikipedia.org/wiki/National_Marine_Electronics_As...

* https://en.wikipedia.org/wiki/NMEA_2000

* https://en.wikipedia.org/wiki/NMEA_0183

Just an FYI, the first link (NMEA OneNet) sounds great, but isn't actually used by any of the major manufacturers yet sadly.

Also, only NMEA2000 is based on CANbus, NMEA0183 is not.

Indeed.

NMEA2000 is essentially a Marine Electronics version of CANBUS with their own agreed upon PGNs.

NMEA0183 is pretty close to RS-232 (and/or RS-422), usually at 4800 baud, but there's a "High Speed" variant at 38,400 baud.

Minor nitpick: NMEA0183 is a text format (based on "sentences"), it's at the protocol layer, RS-422 is the most common transport layer but we often carry it over UDP or TCP too. SignalK can convert and output your data in NMEA0183 on TCP port 10110, for instance.

It's not an alternative to NMEA, thought it definitely started as an open source replacement of NMEA. Cooler heads prevailed and the NMEA body opened some of the IP to SignalK developers. So instead of the opensource hardware that used SignalK as originally envisioned we have the same NMEA based proprietary hardware that SignalK ingest and convert to JSON.

"allows for communication between instruments and sensors on board a single vessel, and also sharing of data between multiple boats, aids to navigation, bridges, marinas and other land-based resources"

So will be finally be able to find out a bridge's name without a cruising guide?

Sharing beyond a boat's internal network isn't much used yet except for a few use-cases.

You need to have a way for the individual boats to share that data. The most obvious way would be to have access to the internet, and host a server somewhere where all the boats would send their data (sensor data, mostly position/heading/speed information).

For example, a regatta could host a server where participants send all their data, enabling a live map with all participant's position and course plotted on it, along with depth & wind instrument readings. This could let spectators understand the participant's performance (how high their point into the wind, etc.)

Navigation information (routes, waypoints, etc) can also be shared over SignalK, altough that's not much used yet as OpenCPN doesn't support it. Again, in the regatta example, you could see a "dynamic" regatta, where the course isn't known in advance.

IMO the main challenge here is having a peer-to-peer "local broadcast" mode, like AIS or DSC. There are regulatory challenges with this, though.

The more obvious way to share data at sea is radio, since it has less latency than out to the internet and then back and works when you aren't near land and don't have Starlink/etc. Is there really no protocol for this yet??

The "standard" radio on boats is the marine VHF, which is voice-only except for Digital Selective Calling (DSC).

DSC is present on "newer" / more expensive radios so it's not a guarantee that a given boat has it. It has a few message types:

- Distress calls

- "Routine call" (basically rings the other boat and asks them to switch to a chosen channel so you can then talk over voice)

- Position request

There's very poor integration between these DSC messages and the rest of marine electronics.

The other radio-based protocol is Automatic Identification System (AIS), which requires dedicated hardware (or a very expensive radio). It transmits your position, heading and speed regularly, and some biographic info (name & dimensions of the boat) from time to time. It's basically ADS-B for boats.

This is very well integrated with all marine electronics and apps. It's also what powers sites like MarineTraffic.

Main issue with both of these is that they aren't really extensible, so you can't send whatever you want over them.

Other radio tech used on boats would be Single-Sideband (SSB), but that's more in the amateur radio realm. Some boats do have a full HAM setup, but it's not that common.

I remember SSB being fairly useful for Weatherfax some years ago, where you plug the radio audio jack into your computer, which had some software to decode the faxes from audio and you get a map of all the bad weather.

I feel like what you describes leaves some large holes in what could be done with radio. Automatic exchange of intended route info for eg could be useful in areas of high traffic. Maybe something LoRa shaped could some of fit them, given its fairly large range.

My only exposure is getting GPS and AIS data out of an OpenCPN computer and relayed to a tablet. Works great for that.

Seems like a lot of regulation will stand in the middle of their path, and that will be adopted only by some sectors (No way military ships will pick this) but is intriguing. Security will be a problem.

Not sure what regulation you're talking about; the only existing standards in this space are either proprietary to one manufacturer (e.g Raymarine's Seatalk), or just industry consensus (e.g NMEA). There's no regulation enforcing the use of either except market forces.

I know for a fact that security has been a big consideration in SignalK's development, but at its core SignalK is only a JSON schema; I don't see why military ships couldn't pick this up if they were so inclined.

For now, it has basically become the standard in the open-source marine ecosystem; used by default in OpenPlotter (a marine-oriented Linux distribution) and supported in OpenCPN (a chartplotter/navigation software).

OpenCPN needs a new maintainer in Debian --0 hint

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