Electronics: NMEA OneNet

NMEA's new protocol will improve onboard network connectivity and security.

October 18, 2018
Electronics: NMEA OneNet Courtesy of Jeremie Lecaudey/Volvo Ocean race

Ashore, our new best friends Alexa and Siri put us in touch with the internet of things, the networked devices all around us. Soon the day will come when we can take them sailing too, and tap into an “ocean of things” — not to mention the boatload of devices we use underway for comfort, ­navigation and entertainment.

Sailors tend to get branded as conservative types, given the levels of risk and mandatory self-sufficiency that we regularly engage when we slip our mooring lines, but the reality is far different, especially when it comes to networked instrumentation. Since the days of the earliest navigators, mariners have sought ways to measure and track variables such as wind speed and direction; speed over the ground and through the water; heel angle; and position information. In the early stages of electronic navigation, much of that information was collected and displayed on discrete instrumentation. But today’s sailors benefit from having all of this data aggregated in one place, which enables interoperability, such as allowing the radar to use networked GPS information. And now, we’re on the verge of being able to do a whole lot more, thanks to a new network protocol about to be introduced by the National Marine Electronics Association: OneNet.

To date, sailors and equipment manufacturers have linked compatible devices using NMEA 0183 and, more recently, NMEA 2000 data backbones. But these are relatively low-bandwidth systems that service a limited number of networked devices. This has worked well in a closed-loop, off-the-grid environment, such as a sailboat operating offshore without connectivity. But speed, bandwidth and network-security demands change dramatically when raw radar and sonar data feeds are being shared with networked wireless devices.


While NMEA’s new and not-yet-released OneNet protocol won’t replace your vessel’s NMEA 0183 or NMEA 2000 network when it comes to sharing safety-­critical real-time navigation data, OneNet will use Internet Protocol version 6 (IPv6) architecture to deliver faster data-transfer speeds, support high-bandwidth applications and provide significantly higher levels of network security, while also making it easier and faster to add new devices and instrumentation to a network. Moreover, OneNet is designed to augment NMEA 2000 with seamless connectivity between the two networks.

Some history: OneNet began in 2010, when a group of marine brands asked NMEA to create a standardized protocol for transmitting and receiving NMEA 2000 messages over an Ethernet network. While individual brands have used Ethernet cables to connect, say, their radars and chart plotters, this was implemented in a proprietary manner that didn’t allow for much interoperability with devices from other manufacturers.

Now, eight-plus years later, NMEA is poised to release its new OneNet standard for sharing NMEA network messages (NMEA 2000 and OneNet protocols use a common NMEA network-message database) via Ethernet using IPv6. Data will be shared in a nonproprietary common format that’s designed to enable interoperability and provide significant amounts of built-in future-proofing.


Steve Spitzer, NMEA’s director of standards, says OneNet’s primary objective is to provide significantly higher levels of network security, while also simplifying the process of finding and adding new devices to the network. Here it’s important to understand that the kind of security involved isn’t designed to deter Russian hackers from pilfering the financial information that you might be transmitting over your iPhone, but rather bigger-picture protections. “It’s not personal data but [the boat’s] actual navigation and operations that could be hacked,” Spitzer says. “When published, OneNet will have a robust security system, and it will be able to discover new devices, just like at home.” (In layman’s terms, imagine pairing your smartphone with a Bluetooth-enabled speaker.)

“I can’t overemphasize OneNet’s security,” Spitzer says. An owner could secure a OneNet network so only NMEA-certified instruments could have access, or the network could be opened to allow a broader range of devices. In all cases, the network’s owner will have ultimate veto power over any device or software that attempts to access the network and its interconnected systems and instrumentation.

“For commodity devices such as a smartphone or tablet, we don’t expect the iPad to be OneNet-certified, but the application that it’s running needs to be certified,” Spitzer says.


Additionally, when secure operation is enabled, each networked device encrypts its outgoing messages before sharing them with the OneNet network. Once received, the other networked devices authenticate the message before unencrypting and using the data.

OneNet’s physical data backbone supplies a maximum of 25.5 watts of power to all plugged-in instruments, through power over Ethernet. This means that segments of a single cable (along with OneNet switches) can both power a device and let it ­communicate with the network. And it’s fast. OneNet delivers 5G data transfer speeds of 100 megabits per second to 10 gigabits per second. By comparison, the data transfer on an NMEA 2000 network is 250 kilobits per second. Also, OneNet will support a virtually unlimited number of devices, while NMEA 2000 networks are limited to 52 physical devices.

OneNet will create a ­powerful Ethernet ­backbone for sharing data among the many devices aboard a sailboat, including high-­bandwidth satellite and video feeds. Courtesy of the manufacturers

Spitzer says it was the decision made in 2013, at the behest of Cisco Systems, to adopt the IPv6 architecture, rather than the older, more limited IPv4, that did the most to help future-proof OneNet. “There are no more IPv4 addresses available for North America,” Spitzer says. “Does a boat need endless IP addresses? No. But it’s the connectivity that we wanted,” he says, referring to a user’s ability to interact with the now-ubiquitous internet of things via an onboard network.


“A cruiser could turn the lights on and off at his home while he’s in Barbados on his boat, and he could look at his at-home security cameras, all through his boat’s satellite communications system,” Spitzer says, explaining the flexibility that IPv6 architecture provides. Also, OneNet devices might eventually be involved with predictive-­maintenance analytics that could help to lower overall costs to the sailboat owner.

The IPv6 protocols also allow for significantly improved automatic network-­configuration capabilities and multicast routing (data can be simultaneously delivered to multiple networked devices or instruments) compared to IPv4, as well as the ability to access cloud-based data. Provided that the vessel has internet connectivity, OneNet users will eventually be able to access real-time data from the Defense Advanced Research Projects Agency’s Ocean of Things project. The project will deploy thousands of networked low-cost floats that will use commercially available, off-the-shelf sensors to collect environmental data (wave or wind information) and form a distributed sensor network.

“Ocean of Things has much more potential for mariners than the internet of things,” Spitzer says. “And the only way to access this information is via IPv6, which is OneNet.”

Harnessing this data will eventually allow for real-time weather routing, enabling sailors to enjoy faster, more comfortable passages while also buying additional safety margins for dodging nasty weather.

While a new data backbone that has the ability to network with wired and wireless devices likely isn’t as exciting to most cruisers as a new suite of sails, it provides significant real-world benefits, ranging from assurances that your nav system won’t be hijacked or spoofed to enabling users to send video over the network. While this was incorporated more with an eye toward video-monitoring of the engine rooms of large commercial ships, it also benefits sailors who use video or thermal-­imaging cameras.

Another important benefit to end-users is that OneNet was designed to be scalable as newer technologies and Ethernet-based applications evolve. For example, OneNet already supports contemporary internet architecture, and it was designed to evolve as fiber-optic cables and next-­generation connectors eventually step aboard both new builds and refits. OneNet’s adoption will start with people who want the latest and greatest, Spitzer says. “I suspect the retrofit market will be the first market, then new builds.”

To install OneNet, a boat owner will first need Ethernet switches that support the OneNet network services and OneNet-certified devices. Spitzer says NMEA is hoping to publish the OneNet protocol sometime between October and late December 2018. “There are only minor issues left, nothing major,” Spitzer says. “We’re doing our final due diligence and homework, and we’re trying to find shortcomings in the beta program’s live interoperability testing, which has been two years in the making.” As for when manufacturers will start building OneNet-compatible equipment, Spitzer says that he would be pleasantly surprised to see products in a year and a half or two years.

As of this writing, the NMEA OneNet committee includes more than 65 ­marine-electronics ­manufacturers and the U.S. Coast Guard. The right people are collaborating on creating the protocol. However, early adopters should expect some initial teething pains. “Even when OneNet is published, there will be some development cycle,” Spitzer says. Still, he adds, it might be faster than the adoption of NMEA 2000, which took more than 15 years, because Ethernet is more ubiquitous. “I hope there are a lot of ­manufacturers who are learning to deploy IPv6,” he says.

David Schmidt is CW’s ­electronics editor.


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