What does variation change with?

Variation, also known as magnetic declination, refers to the angle between magnetic north and true north. It changes primarily with geographical location because different locations on the Earth's surface have different magnetic field strengths and angles due to the irregularities in the Earth's magnetic field.

In some areas, the angle differs significantly, and sailors need to account for this variation to navigate accurately. Areas close to magnetic poles might show drastic differences, while variations are less pronounced near the equator.

Understanding how geographical location influences variation is vital for navigators to ensure correct course plotting and safe navigation. The other factors, such as compass type, time, and vessel size, do not directly alter the magnetic declination and hence are not relevant to the concept of variation in navigation.