Relation between the Error by the Compass-bowl-motion and the Directional System

Abstract

Magnetic compasses are essential in nautical instruments especially for small vessels. From the view point of the safety, it is important to study every error of the magnetic compasses. The indication error due to ship's roll and pitch on the magnetic compass bowl had already mentioned in our former report. This paper describes about the experimental results upon the errors caused by the artificial movement simulated as ship's roll and pitch in the case of using a model card and bowl having a few clearances made between the edge of the card and the upper glass (upper clearance), between the outer edge of the card and the inside of the bowl (edge clearance), as well the area of the card. These results show that this error increases with the edge clearance, decreases with upper clearances and the card areas. Consequently, it becomes that a profitable design about these dimensions of a directional system exists in each size of the card.