The sextant is an instrument used to measure angles. Its arc is one sixth of a circle. Hence it is called a sextant.In actual practice, the arc of the sextant is about 60°. Being an instrument of double reflection, it can measure angles up to
A change in draught may arise during a voyage due to factors such as cargo and ballast changes as well as sea water density, and dynamic factors such as squat, pitch /roll etc. These factors should be considered in the appraisal and appropriate figures calculated