Draft (sail)

In nautical parlance, the draft or draught of a sail is a degree of curvature in a horizontal cross-section. Any sail experiences a force from the prevailing wind just because it impedes the air's passage. A sail with draft also functions as an airfoil when set at an angle slightly greater than the angle of the wind, producing lift which then propels.

The word "belly" is also used in reference to the draft of a sail (i.e. "More belly in the main sail.").

References

Draft

Draft or draught may mean:

Watercraft dimensions

Selection processes

Entertainment

Draft (engineering)

In engineering, draft is the amount of taper for molded or cast parts perpendicular to the parting line. It can be measured in degrees or mm/mm (in/in).

Consider the fabrication of a hollow plastic box, without lid. Once the plastic has hardened around the mold, the mold must be removed. As the plastic hardens, it may contract slightly. By tapering the sides of the mold by an appropriate "draft angle", the mold will be easier to remove.

If the mold is to be removed from the top, the box should taper in towards the bottom, such that measuring the bottom internal dimension will yield a smaller length and width than measuring the top from which the mold is extracted.

By specifying the opening length and width, a draft angle, and a depth, it is not necessary to specify the dimensions for the internal surface, as these may be calculated from the above.

The manufacture of a part that incorporates zero or negative angles may require a mold that can be separated into two or more parts, in order to release the casting.

Draft (sports)

A draft is a process used to allocate certain players to sports teams. In a draft, teams take turns selecting from a pool of eligible players. When a team selects a player, the team receives exclusive rights to sign that player to a contract, and no other team in the league may sign the player.

The best-known type of draft is the entry draft, which is used to allocate players who have recently become eligible to play in a league. Depending on the sport, the players may come from college, high school or junior teams or teams in other countries.

An entry draft prevents expensive bidding wars for young talent and ensures that no one team can sign contracts with all of the best young players and make the league uncompetitive. To encourage parity, teams that do poorly in the previous season usually get to choose first in the postseason draft, sometimes with a "lottery" factor to discourage teams from purposely losing.

Other types of drafts include the expansion draft, in which a new team selects players from other teams in the league; and the dispersal draft, in which a league's surviving teams select players from the roster of a newly defunct franchise.

Sail

A sail is a catchment device designed to receive and redirect a force upon a generous surface area. Traditionally, the surface was engineered of woven fabric and supported by a mast, whose purpose is to propel a sailing vessel. Sails may be configured in many ways to include traditionally understood maritime purposes, as well as land vehicles and solar collection purposes. The rich encyclopedic history of maritime sails suggests alternative uses of the technology well documented.

History of sails

Archaeological studies of the Cucuteni-Trypillian culture ceramics show use of sailing boats from the sixth millennium onwards. Excavations of the Ubaid period (c. 6000 -4300 BC) in Mesopotamia provides direct evidence of sailing boats. Sails from ancient Egypt are depicted around 3200 BCE, where reed boats sailed upstream against the River Nile's current. Ancient Sumerians used square rigged sailing boats at about the same time, and it is believed they established sea trading routes as far away as the Indus valley. The proto-Austronesian words for sail, lay(r), and other rigging parts date to about 3000 BCE when this group began their Pacific expansion.Greeks and Phoenicians began trading by ship by around 1,200 BCE.

Sail (Lake District)

Sail is a hill in the English Lake District, lying between Derwentwater and Crummock Water.

Topography

The North Western Fells occupy the area between the rivers Derwent and Cocker, a broadly oval swathe of hilly country, elongated on a north-south axis. Two roads cross from east to west, dividing the fells into three convenient groups. The central sector, rising between Whinlatter Pass and Newlands Pass, includes Sail. The highest ground in the North Western Fells is an east-west ridge in this central sector, beginning with Grasmoor above Crummock Water and then gradually descending eastwards over Crag Hill, Sail, Scar Crags and Causey Pike.

Sail is in every sense a satellite of Crag Fell, although having sufficient prominence to be listed as a Hewitt. From the summit of Crag Hill the eastward ridge narrows between opposing walls of crag. This rocky crest is The Scar, the depression being at around 2,425 ft. The roughness decreases as the rounded top of Sail is reached, and the ridge then turns east north east. A further depression at 2,015 ft leads to the summit of Scar Crags. This col is unnamed on maps of the Ordnance Survey, but Alfred Wainwright termed it Sail Pass in his influential Pictorial Guide to the Lakeland Fells

Sail (anatomy)

A sail is a large, flattish protrusion from the back of an animal colinear with the spine. Many extinct species of amphibians and reptiles have very extended neural spines growing from their back vertebrae. These are thought to have supported a sail. Paleontologists have proposed many ways in which the sail could have functioned in life.

Function

Many suggestions have been made for the function of the sail. The consensus amongst modern scholars is that, at least for the pelycosaurs, the sail was used for thermoregulation.

Thermoregulation

The structure may have been used for thermoregulation. The base of the spines have a channel which it is proposed contained a blood vessel supplying abundant blood to the sail. The animal could have used the sail's large surface area to absorb heat from the sun in the morning. As ectotherms they required heat from an external source before their muscles would start to function properly. A predator would thus have an advantage over its slower moving prey. The sail could be used in reverse if the animal was overheating. By standing in the shade, the sail would radiate heat outwards.