#### Recommendations for Using Radar Image in Navigation

```{important}
The radar image is an **additional tool** for enhancing navigational safety, but it does **not replace** visual observation, the use of a compass, echo sounder, or other primary navigational aids.
```

##### Verifying Radar Image Overlay Quality

Before using the radar image for navigational purposes, ensure that:

1. **Scale consistency:** the radar image must correspond to the current chart scale
2. **Overlay accuracy:** radar objects (coastline, islands, headlands, isolated point references, navigational marks, radar beacons) must align with their representation on the chart
3. **Signal quality:** the radar image must be clear, without distortion or artifacts, as far as achievable under the current conditions and circumstances
4. **Heading validity:** ensure that the heading is received correctly (required for proper radar image overlay)

```{warning}
When using the **Radar Overlay** function, a guaranteed heading broadcast rate of at least 10 Hz is required. At a lower rate, under conditions of abrupt maneuvering and a large number of point objects, the **radar image** may "scatter."
```

```{danger}
If a discrepancy between the radar image and the ENC is detected when matching known chart objects, determine the cause **immediately**.
```

It is important for the navigator to accurately determine the cause of the discrepancy between the **radar image** and the ENC, as the subsequent actions of the navigator may depend on the cause of the discrepancy.

When determining the cause of the discrepancy, it is important to exclude the influence of configuration changes:
 - antenna alignment has been disturbed;
 - changes have been made to vessel dimensions;
 - GNSS antenna coordinates have been changed or not set;
 - radar antenna coordinates have been changed or not set;
 - CCRP coordinates have been changed or not set;
 - the correct constant heading sensor correction has been changed or not set.

```{warning}
The navigational radar must also be subjected to the same checks.
```

Having excluded technical causes of the discrepancy, verify the vessel's position using {doc}`manual observations </sections/instruments/manual-observations/index>`, as far as possible under the current conditions and circumstances.

If systematic drift or degradation of the GNSS signal is detected, perform the actions and procedures prescribed by the company.
