A barometer is used to measure atmospheric pressure and is used as scientific equipment over ships and marine vessels. A pressure tendency can be used to forecast short term changes in the weather, an essential tool for it is the barometer necessary for sailing route. As the elevation does not change for ships, barometers are widely used for marine sailing. It is highly reliable and measure aneroid movements accurately. It is fully adjustable with inch and millibar scales. Barometer movements are calibrated for ships usage and also for other marine vessels.