Autopilot NMEA 2000: What You Need to Know

What NMEA 2000 is

NMEA 2000 is the modern marine interface standard from the National Marine Electronics Association. The NMEA describes it as a CAN based data network that interconnects marine electronic equipment, with multiple transmitters and receivers sharing data over a single channel. The network is multi-master and self configuring, so there is no central controller that decides which device talks to which.

For a buyer, the practical point is that an autopilot on a NMEA 2000 network can exchange heading, position, navigation and status data with other certified equipment. That is why a listing for an autopilot often mentions NMEA 2000, N2K, or a maker's network name. The difference between the older NMEA 0183 and NMEA 2000 is covered separately in the NMEA 0183 versus NMEA 2000 article.

Why an autopilot needs a network

An autopilot holds a course by reading a heading source and driving the steering system. On a networked boat, the same data can come from other instruments, and the autopilot can send its status back to a display. The maker's page is the only reliable source for what a specific autopilot accepts. For more on how an autopilot talks to a chartplotter, see the chartplotter integration article.

Raymarine describes its Evolution autopilots as systems built around an actuator control unit and a 3D heading sensor at the heart of the system. Furuno's NavPilot 300 requires a Furuno PG700, SC33, SCX20, or another compatible NMEA 2000 heading source. Those details are exactly the kind of thing to check on the maker's page before you buy.

What data moves across the network

The NMEA 2000 standard includes a suite of message types, called PGNs, that cover GNSS, navigation, alerts, AIS and DSC, engine data, and more. An autopilot uses the messages that carry heading, course, position and route data.

What an autopilot does with that data depends on the model line. Some autopilots follow a route from a chartplotter, covered in the route following article; others use wind data on a sailboat, covered in the wind mode article. The listing and the maker's page decide what each autopilot supports, not a general article.

Backbone, drop cables and connectors

A NMEA 2000 network is laid out with a main cable, usually called the backbone, and shorter cables that drop from the backbone to each device. Power enters the network at one point, and each device connects through a standard plug. The exact lengths, connectors and power supply are in the maker's manual and the network standard.

This site does not give installation instructions. A qualified installer or dealer handles the wiring, and the maker's manual covers the details. When you read a listing, 'backbone' and 'drop cable' may appear as words, but a pack usually does not include them. Ask the seller what cables are in the box. For planning questions, see the installation planning article.

Network names on a listing

Listings use different names for the network. N2K is shorthand for NMEA 2000. SeaTalk is Raymarine's network name, and SimNet is Simrad's network name. A listing may say 'N2K ready' or 'SeaTalkng compatible.'

Be careful with 'compatible with' in a title. The catalogue cannot verify compatibility; the maker's page is the source. If a listing says a unit works with a certain network, confirm it on the maker's page before ordering.

What a listing cannot say: it cannot tell you whether your existing chartplotter or heading sensor will talk to a given autopilot. Only the maker's page and the dealer can answer that.

Questions to ask before you buy

Before you order an autopilot pack, ask the seller or the dealer these questions.

• Does this autopilot connect to NMEA 2000, or does it use a proprietary network?
• Does the pack include the cables and connectors, or are they separate?
• Is a heading sensor required, and is it in the box or an extra?
• Will my existing chartplotter share route data with this autopilot? Check the maker's page.
• Who will install the network connections: a dealer, a qualified installer, or you per the maker's manual?
• What does N2K or the network name mean on this listing, and what does the maker's page say?

How NMEA 2000 fits into choosing a pack

Complete packs and core packs differ in what is in the box, not in the network standard. A complete pack usually includes a control head and a drive; a core pack may not. Both can be NMEA 2000 capable. See the core pack guide and the complete pack guide.

If you already have a chartplotter and a heading source, a core pack may be the right starting point. If you want one control head at the helm, look at the control head guide. For an overall comparison, start with the marine autopilot guide.

The network does not replace the watch

An autopilot holds a course, but it does not replace a lookout. The U.S. Coast Guard's Boating Safety division is dedicated to reducing loss of life, injuries and property damage on U.S. waterways, and keeping watch remains the operator's duty. See the U.S. Coast Guard Boating Safety page for education and safety information.

This site makes no safety claims for any autopilot. Ask the dealer about any alarms a listing names, and read the maker's manual for what they do.

What to pick for your situation

Questions

Is NMEA 2000 the same on every brand?

The standard is the same, but brands may use their own network names such as SeaTalk or SimNet. The maker's page is the source for what a specific autopilot accepts.

Do autopilot packs include the network cables?

Not always. A pack may name the control head and drive but leave cables and connectors separate. Read the listing and ask the seller.

Do I need a heading sensor if the autopilot says NMEA 2000?

Some autopilots need a compass or heading source on the network. Furuno's NavPilot 300, for example, requires a Furuno PG700, SC33, SCX20, or another compatible NMEA 2000 heading source. Check the maker's page.

Can I add a NMEA 2000 network to a boat that does not have one?

Yes, in general terms. A network is built with a backbone and drop cables, and the installation is done by a qualified installer or per the maker's manual. This site gives no installation steps.

What does N2K mean on a listing?

It is shorthand for NMEA 2000. Some listings use it in the title or the bullet list.

Will my chartplotter talk to the autopilot?

If both are NMEA 2000 certified, the standard is designed for shared data. Compatibility beyond that is a maker's page question, not a listing claim.