How Did Square Rigged Ships Sail Upwind?

Square-rigged ships, also known as square-riggers, can sail upwind using sideways force generated by square sails. Fore-and-aft rigs can point higher into the wind, but some large ships tried compromises with hermaphrodite rigs to gain an ability to point higher without losing the downwind power advantage. Square-rigged vessels could only sail approximately sixty degrees into the wind and often used a shallow zig-zag pattern to reach their destination. Sailors on deck were responsible for monitoring these ships.

When sailing downwind, the sails are set at right angles to the wind, pushing the ship forward. This is a generic type of sail and rigging arrangement in which the primary driving sails are carried on horizontal spars perpendicular to the keel. The ships were made of overlapping planks of wood to give strength and flexibility to withstand rough seas. The mast of a square-rigged ship carries far more canvas than the same mast fore-and-aft rigged, and there is room to carry three big staysls between the masts.

Sails work like parachutes, creating drag by being perpendicular to the wind. To turn, the ship’s wheel shifts the rudder, changing the flow of water underneath the ship. To slow down, sail area is reduced by hoisting. Most sails on a square-rigger were square-rigged and well optimized for off-wind sailing.

Sails are attached to long horizontal spars of wood called yards suspended above the deck through a complex system of ropes. A square rigger can sail about 6 points (70 degrees) from the wind, which means they have to sail nearly three miles in braced into the wind.