Integrated vs External Compass for Autopilot

What the names mean on a listing

When you read an autopilot listing, the words "integrated compass" or "external compass" describe where the heading sensor lives. An integrated compass is built into another component, usually the course computer or the control head. An external compass is a separate unit that connects to the autopilot system by cable. For an overview of the choices, see the marine autopilot reviews.

The distinction matters because the compass is the part that senses the boat's heading. Where it sits affects how well it can do that job. Magnetic interference from nearby electronics, wiring, or metal can disturb a compass, so placement is a real buying consideration.

• Integrated compass: built into the autopilot's main unit, no separate sensor to mount.
• External compass: a standalone heading sensor that you place separately.
• Some listings name the sensor type, such as "3D heading sensor" or "rate gyro."

Mounting flexibility: where the sensor can go

An integrated compass is fixed to the component it lives in. If that component is the control head at the helm, the compass is at the helm. If it is the course computer, the compass is wherever that unit is mounted. You do not get to choose a separate spot for the sensor.

An external compass is a separate box that you can mount in a location of your choice, within the limits of the cable length and the maker's instructions. This gives you the freedom to find a spot that is away from obvious sources of magnetic disturbance, such as large metal masses, electric motors, or high-current wiring.

For boats with a crowded helm or a lot of electronic gear, an external sensor can be the practical answer. For a simple installation where the integrated location works well, the convenience of a built-in compass is hard to beat. If you are assembling a system from parts, check the best autopilot core packs to see what is included.

Magnetic interference resistance

A compass works by sensing the Earth's magnetic field. Anything that creates its own magnetic field, or that distorts the field nearby, can interfere with that sensing. Common sources on a boat include speakers, electric motors, steel beams, and wiring carrying direct current.

An integrated compass is at the mercy of its location. If the control head or course computer sits near a source of interference, the compass may see that disturbance. An external compass can be mounted farther away from those sources, which is why many boaters choose one when the helm is crowded with gear. For powerboats with busy helm stations, an external sensor is often the safer route; see the best powerboat autopilots.

No autopilot maker publishes a guarantee about how much interference a given mounting spot will have. The practical approach is to look at where the integrated unit would sit on your boat, and if that spot is near obvious magnetic sources, consider an external sensor.

What the catalogue tells you, and what it does not

The catalogue on this site lists the parts that come in a pack, including whether a control head or drive is in the box. It also names the model line, such as Raymarine Evolution or Furuno NavPilot. What it does not state is how a particular compass performs in a particular boat.

The maker's page is the source for what is in a pack and what the sensor is called. For example, Raymarine describes its Evolution sensors as "the autopilot central processor and 3D heading sensor at the heart of every Evolution autopilot system." Furuno notes that some NavPilot models require a separate heading source, such as a PG700 or SC33.

When a listing does not say whether the compass is integrated or external, that is a detail to ask the seller about. The absence of the word "external" does not mean the sensor is integrated; it may just be unstated.

How to choose for your boat

Start by thinking about where the autopilot's main unit will go. If you are replacing an old autopilot, the new unit may fit in the same spot. If that spot is near a compass, a radio, or a steel bulkhead, an external sensor gives you an escape route. For a full system that includes everything, compare best complete autopilot packs.

For a small sailboat with a tiller pilot, the autopilot is often self-contained, with the compass built in. That is usually fine because the unit sits in the cockpit, away from the worst of the helm electronics. Look at best tiller pilots for self-contained options.

For a powerboat with a crowded helm, an external compass is often the safer choice. You can mount the sensor in a locker or under a deck, away from the displays and wiring that fill the dash.

The choice is not about which is better in the abstract. It is about which fits your boat's layout and your willingness to run one more cable.

What to pick for your situation

The table below matches common situations to the type of sensor that usually makes sense. Use it as a starting point, then check the maker's page for the specific pack you are considering.

What to pick for your situation

Questions

What is an integrated compass in an autopilot?

An integrated compass is a heading sensor that is built into another autopilot component, such as the course computer or control head. It saves space and simplifies installation because there is no separate sensor to mount. For a list of autopilots with control heads, see best autopilots with control head.

Why would I want an external compass?

An external compass is a separate sensor that you can mount away from magnetic interference. This is useful if the integrated location is near electronics, wiring, or metal that could disturb the compass.

Does an external compass always perform better?

No. Performance depends on where the sensor is mounted and the quality of the sensor itself. An external sensor gives you more placement flexibility, but you still need to choose a good location.

How do I know if a pack has an integrated or external compass?

Check the listing for the words "integrated" or "external," or look for a separate sensor part number. If it is not stated, ask the seller or check the maker's page for the pack contents.

Can I add an external compass to a pack that has an integrated one?

Some autopilots allow an external heading source to be connected, but this depends on the specific model. Check the maker's page or ask a dealer whether the system supports an external sensor.

What is a 3D heading sensor?

A 3D heading sensor is a type of compass that measures heading in three dimensions, which helps the autopilot account for the boat's motion. It is a term used by some makers, such as Raymarine for its Evolution sensors.