"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.
- Cup anemometer
- 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.
