Marine Anemometer - Working principle and Types

"Marine Anemometer"

The Marine Anemometer is a weather instrument used to measure wind speed and wind direction. The term anemometer is derived from the Greek word "anemos" meaning wind.

There are 2 mainly used anemometer in the marine industry.

1. Cup anemometer
2. Vane anemometer

Cup anemometer:

Working principle:

• Cup Anemometer consists of 4 Hemispherical cups mounted on the end of the horizontal arms.
• Horizontal arms are mounted on a Vertical shaft.
• The airflow passes through the cups in a horizontal direction makes the shaft rotate.
• AC generator connected to the shaft. Faster the shaft rotates higher the electric current will produce.
• AC voltage is rectified to DC voltage and output voltage is measured for set interval and the voltage signal is calibrated to measure the wind speed.
• This type of anemometer gives only wind speed unless the wind vane additionally fitted on the instrument for wind direction.

Vane Anemometer:

Working principle:

• In Vane Anemometer the propeller is fitted, the rotating axis of the propeller must be parallel to the flow of wind.
• To align the body parallel to the wind flow, the tail (wind vane) is designed. so the propeller always faces the wind direction.
• AC generator connected to the shaft. Faster the shaft rotates higher the electric current will produce.
• AC voltage is rectified to DC voltage and output voltage is measured for set interval and the voltage signal is calibrated to measure the wind speed.
• An analog signal is transmitted to the wind speed and direction indicator and the instantaneous wind speed and wind direction are ascertained.