The forecastle of a ship, commonly seen spelled as foc'sle to reflect the truncated pronunciation used by mariners, is the area where sailors sleep and congregate while off duty. The foc'sle is located in the forward part of the ship, also called the bow, and in front of the main mast. The foc'sle serves as accommodations for regular sailors, while officers of the ship are housed in other areas.
The term “before the mast,” which has come to refer to regular sailors, is also a reference to the foc'sle. Individuals knowledgeable about sailing history are familiar with the tradition of housing sailors in the forward part of the ship, or “before the mast.” The term has become familiar in the popular imagination because of the writing of Richard Henry Dana, Jr. who spent two years as an enlisted sailor and wrote about the experiences in a popular 1840 book called Two Years Before the Mast.
The term forecastle has been in use to describe the forward part of a ship since the 1400s, when ships commonly had a raised deck in the front of the ship for use in battles. This raised deck was known as the castle, because it resembled a fortified castle, and the deck area in front of the castle came to be known as the forecastle. As well as providing quarters and a social area, the foc'sle is also a crucial observation point, and sailors are often stationed there to keep an eye out for navigational hazards. During the anchoring process, the foc'sle is usually alive with activity as sailors maneuver the heavy anchors.
Machinery related to the operation of the ship along with spare ropes and sails are also stored in the foc'sle. The anchor windlass used to wind up the anchor chains is commonly on the forward part of the foc'sle, along with the anchors themselves. In addition, weapons are kept in a locker on the foc'sle to be readily accessible in case of need. The foc'sle is also used as a social area, and ships with more room forward will sometimes make accommodations for this.
Quarters within the foc'sle are often divided depending on speciality. The rigging crew, answerable to the boatswain or bosun, would bunk in a separate area of the foc'sle along with the other regular sailors. Marines, sailors hired to protect the ship in event of attack or to act as an offensive force, were usually berthed in another part of the foc'sle. In the early days of sailing, mixing between regular sailors and marines or between enlisted sailors and officers was not encouraged, and divided sleeping quarters emphasized this.