A lateen is a sail configuration dating back to ancient times and still in regular use on a variety of vessel types today. It consists of a triangular, fore and aft sail suspended from a yard. The yard crosses the mast at approximately its midpoint with its forward end almost at hull level and its rear pitched up above the top of the mast. This arrangement places the yard and sail at an angle of around 45° to the mast and equally positioned behind and in front of it. Lateen rigged vessels may have one or more masts and can include additional sails such as jibs or foresails.
The exact origins of the lateen rig are unclear; several historians believe it was in use as far back as the first century BC. It was widely used on vessels of the Roman Empire in the Mediterranean and was one of the rigging standards during the Age of Discovery. An evolutionary offshoot of traditional square rigging, the lateen sail found favor among sailors from the Mediterranean to the Indian Ocean where it is still the rig of choice on dhows and smaller fishing vessels.
The lateen sail is a fore and aft design meaning it is orientated along the keel line, or length, of the vessel. The sail is triangular and supported along its upper edge by a long spar or yard. The yard is attached to the mast with parrel lines in the region of its midpoint. The gaff is orientated with its front end secured low towards the bow of the vessel with a tack line. This places its other end in a pronounced pitched up attitude and typically higher than the mast.
The lower edge of the sail may feature an additional spar known as a boom but is generally unsupported. Its rear corner is secured to the vessel by a line known as a sheet which is used to adjust the sail. The yard remains on one side of the mast at all times which lends the rig the disadvantage of a “bad tack” sail position under certain conditions. Bad tack occurs when the wind pushes the sail against the mast, thereby negatively affecting its carrying capacity. On the opposite tack, or when the wind blows from the other side of the vessel, the sail fills away from the mast and achieves full potential.
The lateen rig is a simple arrangement to manage and requires a small crew. It can be dropped and raised quickly, thereby making it an ideal choice for vessels which regularly navigated under bridges. These sails may be appropriate for single- or multiple-mast vessels and are often used in conjunction with jibs and foresails.