> For the complete documentation index, see [llms.txt](https://pcnautic.gitbook.io/autopilot/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://pcnautic.gitbook.io/autopilot/operate/web-interface-apps/compass-calibration.md).
# Compass Calibration
## Compass Calibration
{% hint style="success" %}
A magnetic compass is naturally sensitive to external influences. Interference can be caused by:
* Magnetic objects such as screwdrivers, eyeglass cases, AirPods cases, or magnets in clothing
* Electronic devices, including mobile phones
* Nearby infrastructure such as harbors, bridges, locks, tunnels, high-voltage lines, and underground cables
These factors can result in inaccurate heading readings.
*Tip: For a stable and reliable heading display—especially in areas with strong magnetic interference—we recommend using the GPS ground course whenever possible.*
{% endhint %}
### Magnetic heading
This is the direction the bow of the boat is pointing, relative to **magnetic north**, as measured by the internal compass in the ControlHead.
* 0° = North
* 90° = East
* 180° = South
* 270° = West
### Pitch
Pitch measures the tilt of the bow up or down:
* Positive pitch = bow up
* Negative pitch = bow down
* When the boat is level, pitch should be close to **0°**
### Roll
Roll measures the tilt from side to side:
* Positive roll = leaning to starboard
* Negative roll = leaning to port
* Should also be close to **0°** when the boat is level
{% hint style="info" %}
Both pitch and roll values are provided by the inertial sensors (IMU) inside the ControlHead.
{% endhint %}
### Alignment
Press the button only when the boat is level and stationary in the harbour to align the internal inertial sensors.
{% hint style="warning" %}
Make sure the ControlHead is permanently mounted before alignment. After pressing the button, Pitch and Roll should both be close to zero.
{% endhint %}
### Magnetic Heading Offset
If the ControlHead is mounted facing straight forward, leave the offset at **0°**.
* If mounted sideways:
* **Starboard side:** use **–90°**
* **Port side:** use **90°**
### **Compass Lock Calibration**
Best performed on open water, away from magnetic interference.
* Sail gentle laps both port and starboard.
* When the heading is stable, enable **Compass Lock Calibration**.
{% hint style="info" %}
If you notice inaccurate heading under heeling conditions, consider temporarily unlock — the compass will then learn under those conditions.
{% endhint %}
## Calibration Plot
{% hint style="danger" %}
For experts only
{% endhint %}
On this page you can view a visual representation of the calibration data. You can also configure the lock for both the compass and the accelerometer here.
### **Calibration Locks**
#### **Compass Lock Calibration**
It is best to perform this calibration on open water, away from magnetic interference.
* Sail a few gentle loops to both port and starboard.
* When the heading remains stable, you can enable **Compass Lock Calibration**.
#### **Accelerometer Lock Calibration**
{% hint style="danger" %}
This setting should remain locked during normal operation.
{% endhint %}
Accelerometer calibration is **not required** under regular conditions. **It is performed by us before delivery.**
* The process involves placing the ControlHead briefly on each of its six sides.
* This requires the unit to be removed from its installation.
### **Calibration Type**
Select whether you want to calibrate the accelerometer or the compass. Calibration only takes place when the corresponding lock is disabled.
### **Calibration Parameters**
This section shows the current calibration values for both the accelerometer and the compass. When a new calibration is applied, the “age” will be reset.
---
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