A polacca, also known as a polacre, was a type of sailing vessel, most common in the Mediterranean in the 17th, 18th and early 19th centuries. Most polaccas had three masts, with a variety of different types of sail. Merchants used this type of craft to carry cargo, but polaccas were also used as fighting vessels, both by European navies and by North African corsairs. The name "polacca" probably comes from an Italian word meaning "Polish," although the vessels themselves do not seem to have originated in Poland.
The most common arrangement of sails for a polacca included both lateen and square-rigged sails. These two types of sails had different sailing characteristics and could be combined in a number of different ways. Square-rigged sails were set on spars which ran across the ship horizontally, perpendicular to the line of the keel. Their name comes from this position on the mast, not from their shape, which was narrower at the top than at the bottom.
Lateen sails were large triangular sails set on a long yard which ran fore-and-aft along the line of the keel. This yard was typically high up on the mast at an angle. Lateen-rigged vessels were highly maneuverable but not as fast as square-rigged vessels running before the wind.
The typical polacca carried a lateen sail on its foremast. As a result of the large size of the lateen yard, the foremast would be slanted forward to provide extra space. The mainmast was usually square-rigged, while the mizzen mast carried another fore-and-aft sail, often a lateen or a similar type of triangular sail called a gaff sail. This combination of sails created a balance of speed and maneuverability.
Although this type of sail plan was the most common for a polacca, a large number of variations existed. One variant, the so-called polacre-xebec, had a square-rigged foremast, lateen rigs on the two rear masts, and two sails on the stays between the foremast and bowsprit. These sails were called staysails, headsails or jibs.
In addition to transporting cargo, polaccas could also serve as fighting vessels. Craft of this type included those commanded by Jan Janszoon van Haarlem, alias Murat Reis, a 17th-century Dutch privateer who became a corsair leader. Murat Reis took the port of Salé as his base of operations and conducted raids in the Atlantic, even striking as far west as Ireland. Murat Reis's vessels included polaccas which mounted up to 24 guns.