### Weather Instrument Operational Features

Wind data is displayed in the **Navigational Panel**.

![](images/image535.png)

| No. | Element |
|---|---------|
| **1** | Parameter name |
| **2** | Sensor name |
| **3** | Wind direction (depends on the selected wind type) |
| **4** | Wind speed (depends on the selected wind type) |
| **5** | Wind type selected in the **Wind** tab of the multi-function window |
| **6** | Wind speed units, set in {doc}`**Measurement Units** </sections/system-settings/measurement-units/index>` (m/s, knots, km/h) |

In the **Wind** tab, the selected wind direction relative to the vessel is displayed graphically.

![](images/image536.png)

| No. | Element | Description |
|---|---------|----------|
| **1** | Wind type selection | ![](images/image537.png) |
| **2** | Wind speed | Wind speed of the selected type |
| **3** | Wind direction | Wind direction of the selected type |
| **4** | Wind force | Wind force in Beaufort scale points |
| **5** | Vessel symbol | Orientation always vertical |
| **6** | Compass meridian | From gyrocompass — true, from magnetic compass — magnetic |
| **7** | North direction | Compass north direction (true or magnetic, depending on the heading source) |
| **8** | Wind vector | Wind vector of the selected type<br><br>![](images/image538.png) |

### Wind Types

ECDIS displays three wind types:

- **True Wind** — wind relative to the water surface. Determined by the anemometer taking into account the vessel's heading and speed, or received directly from the sensor if it is installed on a stationary platform.

- **Relative/Apparent Wind** — wind perceived by an observer on a moving vessel. It is the vector sum of the true wind and the opposing flow from the vessel's motion.

- **Calculated Wind** — wind calculated by ECDIS based on anemometer data, heading, and vessel speed. Used when the sensor does not provide direct true wind values.

### Wind Direction Recalculation

Depending on the type of received sentence, ECDIS recalculates wind directions for the navigator's convenience:

1. ``$--MWD`` — True (broadcast), Relative, Calculated.

2. ``$--MWV``:
   - Relative: Relative (broadcast) and Calculated
   - Calculated: Calculated (broadcast)

### Wind Direction Calculation Formulas

Wind direction calculation is performed using the following formulas:

$V_{tw} = \sqrt{{STW}^{2} + V_{aw}^{2} - 2STWV_{aw}\cos\left( K_{aw} \right)}$

$K_{tw} = HDG + K_{aw} \pm KK$

$KK = arccos\left\lbrack \frac{\left( V_{aw} - STW\cos(K_{aw}) \right)}{V_{tw}} \right\rbrack$

**Where:**

- $STW$ — vessel speed, kn.
- $HDG$ — vessel heading
- $V_{aw}$ — apparent wind speed, kn.
- $K_{aw}$ — apparent wind direction, °. If the sensor provides values relative to the vessel's centerline, conversion to the circular geographic system is required:
<br><br>
$K_{geo} = HDG + K_{rel}$ (at 0° ≤ $K_{rel}$ ≤ 180°)
<br><br>
or
<br><br>
$K_{geo} = HDG - K_{rel}$ (at 180° < $K_{rel}$ < 360°)
<br><br>
- $V_{tw}$ — true wind speed, kn.
- $K_{tw}$ — true wind direction
- $KT$ — calculated wind direction
- $VT$ — calculated wind speed
- $KK$ — angle between true and apparent wind

```{important}
Wind parameter calculation is performed when heading and vessel speed data from sensors are available. If heading and speed data are lost, wind value recalculation will be suspended.
```

**Examples of wind data display with various sensor state combinations:**

| Alarm and warning zone | Navigational Panel | Wind tab |
|---------------------|---------------------|---------------------|
| ![](images/image539.png) | ![](images/image540.png) | ![](images/image541.png) |
| <center> No speed data </center> |

<br/>

| Alarm and warning zone | Navigational Panel | Wind tab |
|---------------------|---------------------|---------------------|
| ![](images/image542.png) | ![](images/image543.png) | ![](images/image544.png) |
| <center>No heading data</center> |
