Mainmast

Mainmast is the central and typically the tallest mast on a sailing vessel with multiple masts. On a three-masted ship, the mainmast sits between the foremast toward the bow and the mizzenmast toward the stern; on a two-masted vessel, the mainmast is the aft mast and usually carries the principal sail area. The term can also apply to the central mast on rigs with more than three masts, but is most commonly used for the middle mast in standard fore-and-aft or square rig configurations.

Construction and rigging: The mainmast is anchored into a mast step or keelson and secured by standing rigging—shrouds to the sides and stays fore and aft. It may support yardarms for square sails or carry a mainsail on a fore-and-aft rig. In modern sailboats, the mainmast supports the mainsail via tracks and a boom, with halyards to hoist the sail.

Function: The mainmast provides a large share of a vessel’s sail area and height, contributing to upwind performance and balance. The mainsail (and any topsails on larger rigs) is typically the primary driving sail.

History and notes: As ships grew more complex in the Age of Sail, the mainmast was often the tallest and strongest mast to bear the loads of the main sails. In contemporary sailing craft, the mainmast remains the central reference for rigging and sail plan, and may be built from wood, steel, aluminum, or composite materials depending on vessel type.