Unlike today’s modern GPS that is used, captains had to navigate using charts, Ledgers, the Sun and stars, and an assortment of tools such as the Octant.

This would have been a useful skill to have for any sailor, and quite often was taught to those who had an aptitude for reading and writing. 

The Octant was replaced by the Sextant in the following century and was used primarily on seafaring vessels and early astronavigation by aircraft through the late 20th century, replaced by GPS in the mid-1990s