Forecastle

The forecastle (/ˈfoʊksəl/ ⓘ FOHK-səl; contracted as fo'c'sle or fo'c's'le)[1][2] is the upper deck of a sailing ship forward of the foremast, or, historically, the forward part of a ship with the sailors' living quarters.

A similar but usually much larger structure, called the aftcastle, was at the aft end of the ship, often stretching all the way from the main mast to the stern.

As cannons were introduced and gunfire replaced boarding as the primary means of naval combat during the 16th century, the medieval forecastle was no longer needed, and later ships such as the galleon had only a low, one-deck-high forecastle.

In the Royal Navy of the 17th and 18th centuries, these roles were reserved for older seamen who lacked the agility to go aloft or take other more strenuous duties aboard.

[3] By the end of the 19th century, a raised forecastle had become a typical feature on warships again, in an attempt to keep forward gun positions from getting unacceptably wet on heavy seas.