Aftercastle

{{Short description|Structure behind mizzenmast on sailing ships}}

{{onesource|date=November 2018}}

File:Aftercastle of Meduse-Garneray-IMG 4780.JPG, as seen from the deck]]

File:Galeon turystyczny a4 ubt.jpeg showing both a forecastle (left) and aftercastle (right)]]

File:Gdańsk - Galeon Lew (rufa).jpg

The aftercastle{{pronunciation needed|date=August 2023}} (or sterncastle, sometimes aftcastle) is the stern structure behind the mizzenmast and above the transom on large sailing ships, such as carracks, caravels, galleons and galleasses.{{Cite web |url=https://www.britannica.com/technology/castle-ship-part#ref266987 |title=Castle ship part |website=Encyclopædia Britannica |access-date=8 January 2017}} It usually houses the captain's cabin and perhaps additional cabins and is crowned by the poop deck, which on men-of-war provided a heightened platform from which to fire upon other ships; it was also a place of defence in the event of boarding. More common, but much smaller, is the forecastle.

The corresponding term forecastle today is also used to describe the upper deck of a sailing ship forward of the foremast in general.

As sailing ships evolved, the aftercastle gave way to the quarterdeck, whose span ran all the way to the main mast.