The course sheets
   The sheets' task was to hold the leeward lower corners of the sails the clews -against the wind pressure. From ancient times until the 19th century the method of guiding the course sheets remained the same. A single block was fixed to the clew. The sheet itself was fixed to a ring bolt on the outer side of the bulwarks, reeved through the sheet block, and ran directly inboard -or after the 15th century through a sheave in the bulwarks -where it belayed to a range cleat, or on the Continent from the early 16th century , to a staghorn.

Multiple sheets
   Until the late 10th century multiple sheets were used in Viking ships; they were spliced into the foot rope of the sail, and 8 to 12 rope ends hung down to the deck for the men to hold. The Stenkyrka figurestone, illustrated on the right, shows a clear example of this type of multiple sheet

The middle sheets
   After the middle of the 14th century a further sheet was fitted to the middle of the foot rope, and after the middle of the 15th century there were two of them, one on the foot rope of the mainsail, and one on the foot rope of the bonnet. The sharp vertical centrefold, which can be
seen on the mainsails and sometimes on the foresails of ships between the middle of the 14th and the middle of the 16th century , was a result of these middle sheets, which disappeared again in the mid-16th century

The topsail sheets
    In the second half of the 15th and the early 16th century, when the topsails were still very small, the sheets as well as the braces were taken to the top and belayed there. Shortly after 1500 the topsail sheets were led to the lower yard arm via small blocks, and thence to the deck parallel to the braces

The topgallant and royal sheets
   In the middle of the 16th century the topsail sheet was fixed to the clew with a stopper knot (pictured opposite), reeved through a block at the yard arm situated below it, then ran to a leading block on the inner third of the yard, and finally down to the deck, where it reeved through a sheave in a kevel block, and belayed to its head. The topgallant and royal sail sheets followed a similar course to the topsail sheets, and belayed to the bitts.

The tacks
   Tacks were only used on the courses. Until the first half of the 18th century they were single ropes, which were attached to the clew with a stopper knot. The main tack reeved through the hole in the chesstree into the waist, and belayed on a range cleat. The fore tack ran through square timber with two holes, fixed to the knee of the head until the beginning of the 17th century, around 1630 through a guide below knee of the head, around 1650 through two holes in the knee of the head, and since the first half of the 18th century through a block on the outboard end of the bumkin. In the first half of the 18th century doubled tacks were fitted, reeved through a block fixed to the clew with a stopper knot. This was a Continental development, later adopted by the British.