Navigational instruments, particularly dividers and course plotters, are essential tools for manual navigation at sea. Dividers are used to measure and transfer distances on nautical charts, allowing navigators to accurately gauge the distance between two points using the chart's scale. Course plotters, also known as parallel rulers or navigation triangles, are used to precisely draw or adjust courses on the chart. They enable the transfer of bearings and angles and help in determining the course by sliding them along the chart's meridians. Despite modern GPS technology, navigational instruments remain crucial, especially as a reliable backup and for traditional maritime training.