aftcastle

An aftcastle, also called an aftercastle, is a raised structure at the stern of a sailing ship. It sits on the after part of the upper deck, behind the main deck, and is often two stories tall. The aftcastle is distinct from the forecastle at the bow and from other stern features such as the poop deck or the quarterdeck, though the terminology varies by vessel and era.

The aftcastle typically housed living quarters for officers and sometimes crew, along with spaces used for navigation, signaling, and command. On many ships it provided a sheltered, elevated vantage point from which the helmsman could observe the stern and the sea, and from which signals or orders could be issued. In some designs the helm and steering apparatus were located there or adjacent areas, while on others the wheelhouse or quarterdeck served that function as naval architecture evolved.

Design and function of the aftcastle varied considerably with ship type and period. On older sailing ships it could be a prominent, multideck structure that reinforced the stern and allowed better observation and protection for important spaces. In later vessels the rise of enclosed wheelhouses and specialized quarterdecks reduced or transformed the traditional role of the aftcastle.

Today, the term is primarily encountered in historical contexts, restorations, and descriptions of traditional sailing ships. It is part of the broader vocabulary describing the stern architecture of classical hulls, alongside forecastle, poop deck, and quarterdeck.