Sail-plan

Sailing frigate and its rigging

A sail-plan is a set of drawings, usually prepared by a naval architect. It shows the various combinations of sail proposed for a sailing ship.

The combinations shown in a sail-plan almost always include three configurations:

In all sail plans, the architect attempts to balance the force of the sails against the drag of the underwater keel in such a way that the vessel naturally points into the wind. In this way, if control is lost, the vessel will avoid broaching (turning edge-to-the wind), and being beaten by breaking waves. Broaching always causes uncomfortable motion, and in a storm, the breaking waves can destroy a lightly built boat. The architect also tries to balance the wind force on each sail plan against a range of loads and ballast. The calculation assures that the sail will not knock the vessel sideways with its mast in the water, capsizing and perhaps sinking it.

Terminology

This photo of the Star of India provides not only good view of most of her sails, but also most of her standing and running rigging. The Star of India is berthed in San Diego, California, and is open to the public.

Types of rig

Types of sail

Each form of rig requires its own type of sails. Among them are:

Order

The names of all of the possible square rigged sails on one mast of a sailing vessel from the 19th century

The standard terminology assumes three masts, from front to back, the fore-mast, main-mast and mizzen-mast. On ships with fewer than three masts, the tallest is the main-mast. Ships with more masts number them.

From bottom to top, the sails of each mast are named by the mast and position on the mast, e.g. for the mainmast, from lowest to highest: main course, main topsail, main topgallant ("t'gallant"), main royal, main skysail, and main moonraker. Since the early nineteenth century, the topsails and topgallants are often split into a lower and an upper sail to allow them to be more easily handled. This makes the mast appear to have more "sails" than it officially has.

On many warships, sails above the fighting top (a platform just above the lowest sail) were mounted on separate masts ("topmasts" or "topgallant masts") held in wooden sockets called "tabernacles". These masts and their stays could be rigged or struck as the weather and tactical situation demanded.

In light breezes, the working square sails would be supplemented by studding sails ("stuns'l") out on the ends of the yardarms. These were called as a regular sail, with the addition of "studding". For example, the main top studding sail.

The staysails between the masts are named from the sail immediately below the highest attachment point of the stay holding up the staysail. Thus, the mizzen topgallant staysail can be found dangling from the stay leading from above the mizzen (third) mast's topgallant sail to some place (usually two sails down) on the second (main) mast.

The jibs, staysails between the first mast and the bowsprit were named (from inner to outer most) fore topmast staysail (or foretop stay), inner jib, outer jib and flying jib. All of the jib's stays meet the foremast just above the fore topgallant. Unusually, a fore royal staysail may also be set.

Material

Sails were classically made of hemp or cotton. They are now made from polyesters (Dacron and PET film), sometimes reinforced with crystalline hydrocarbons (Kevlar and Spectra). Some large, lightweight sails are made of polyamides (nylon).

Lines

In the age of sail, lines were made of manila, cotton, hemp, or jute. Modern lines are made of polyester (Dacron), polyamides (nylon), and sometimes crystallized hydrocarbons (Kevlar and Spectra). Standing rigging may include wire rope made of stainless or galvanized steel. Other older, or less common materials include papyrus in ancient Egypt and coir.

Rigging

Sprit and stays

The stays on a ship roughly form hoops of tension holding the masts up against the wind. Many ships have been "tuned" by tightening the rigging in one area, and loosening it in others. The tuning can create most of the stress on the stays in some ships.

Types of ships

Examples of historic rigging for two masted ships

Sailboat types may be distinguished by:


Proa

Constructed using stone age tools, variations on the crab claw sail rig on various sized open ocean canoes carried the Pacific island navigators on regular long range trips. Both ends are alike, and the boat is sailed in either direction, but it has a high windward side and a lower leeward side supported by an outrigger.

Sunfish

A variation on the proa with a single unstayed mast and a single sail, which uses upper and lower spars like a crab claw sail but which pivots around the mast like a lateen. The usage of two straight spars allows for the sails to be cut straight without any camber factored in, making the sails considerably simpler to manufacture.

Bragana or felucca

A classic in the Mediterranean or Indian Ocean. Three lateen sails in a row.

Catboat

A sailboat with a single mast and single sail, usually gaff-rigged. This is the easiest sail-plan to sail, and is used on the smallest and simplest boats. The catboat is a classic fishing boat. A popular movement among home-built boats uses this simple rig to make "folk-boats". One of the advantages of this type is that it can be rigged with no boom to hit one's head or knock one into the water. However, the gaff requires two halyards and often two topping lifts. The weight of the gaff spar high in the rigging can be undesirable. The gaff's fork (jaws) is held on by a rope threaded through beads called trucks (US) or parrel beads (UK). The gaff must slide down the mast, and therefore prevents any stays from bracing the mast. This usually makes the rig even heavier, requiring yet more ballast.

Sloop

A Bermuda or gaff mainsail lifted by a single mast with a single jib bent onto the forestay, held taut with a backstay. The mainsail is usually managed with a spar on the underside called a "boom". One of the best-performing rigs per square foot of sail area and is fast for up-wind passages. This rig is the most popular for recreational boating because of its potential for high performance. On small boats, it can be a simple rig. On larger sloops, the large sails have high loads, and one must manage them with winches or multiple purchase block-and-tackle devices.

Gunter

A rig designed for smaller boats where the mast is often taken down. It consists of a relatively short mast (usually slightly shorter than the boat so that it can be stowed inside) and a long gaff (often only slightly shorter than the mast). However, rather than the usual trapezoidal shape of a gaff sail, it is triangular, like a Bermuda rig. This allows the gaff, when hoisted, to pivot upwards until it is vertical, effectively forming an extension to the mast. Thus a decent-sized sailing rig can be added to the boat while still allowing all the equipment to be stowed completely inside it. The popular Mirror class of dinghy is gunter rigged for this reason.

Lugger

Sailing fifie

Similar to a gaff rig but the a lugger's gaff does not attach to the mast. Instead, it is allowed to move forward and aft of the mast and is managed through a series of lines that attach to the gaff and to the corners of the sail. May or may not have a boom along its foot. In Scotland, when constructed with a main dipping lug sail and a mizzen standing lug sail, such vessels were known as fifies, sailing fifies, or herring drifters, and were often used for herring fishing.

Cutter

A small single-masted ship with fore-and-aft rigging on its only mast and with two or more headsails; frequently a bowsprit as well. Better than a sloop for light winds, it is also easier to manage, due to the sail area being split up between smaller sails which require less force to trim as compared to the larger single jib of the sloop. The mast is located at about 50% of boat length.

Yawl

A small ship, fore-and-aft rigged on its two masts, with its mainmast much taller than its mizzen and with or without headsails. The mizzen mast is located aft of the rudderpost, sometimes directly on the transom, and is intended to help provide helm balance.

Ketch

A small ship with two masts, both fore-and-aft rigged, with the mizzen located well forward of the rudderpost and of only slightly smaller size than the mainmast (if the height of the masts were reversed—the taller in the back and the shorter in the front—it would be considered a schooner). Historically the mainmast was square rigged instead of fore-and-aft, but in modern usage only the latter is called a ketch. The purpose of the mizzen sail in a ketch rig, unlike the mizzen on a yawl rig, is to provide drive to the hull. A ketch rig allows for shorter sails than a sloop with the same sail area, resulting in a lower center of sail and less overturning moment. The shorter masts therefore reduce the amount of ballast and stress on the rigging needed to keep the boat upright. Generally the rig is safer and less prone to broaching or capsize than a comparable sloop, and has more flexibility in sail-plan when reducing sail under strong crosswind conditions—the mainsail can be brought down entirely (not requiring reefing) and the remaining rig will be both balanced on the helm and capable of driving the boat. The ketch is a classic small cargo boat.

Junk

Chinese Junk sail plan

The standard Chinese design: The sails are made flat with bamboo inserts (battens), permitting them to sail well on any point of sail. Easy to sail, and reasonably fast. The nature of the rig places no extreme loads anywhere on the sail or rigging, thus can be built using light-weight, less expensive materials. Some of the largest sailing ships ever constructed were junks for the Chinese treasure fleet. Junks also customarily had internal water-tight rooms. They remained water-tight because they had no door to other water-tight compartments. Movement was over the wall by ladders or companionways. Usually they were constructed of teak or mahogany.

Schooner

A fore-and-aft rig having at least two masts, with a foremast that is usually smaller than the other masts. Schooners have traditionally been gaff-rigged and in small craft are generally two-masted, however many have been built with marconi rigs (and even junk rigs) rather than gaffs and in the golden age of sail, vessels were built with as many as seven masts. One of the easiest types to sail, but performs poorly to windward without gaff topsails. The extra sails and ease of the gaff sails make the rig easier to operate, though not necessarily faster, than a sloop on all points of sail other than up-wind. Schooners were more popular than sloops prior to the upsurge in recreational boating. The better performance of the sloop upwind was outweighed for most sailors by the better performance of the schooner at all other, more comfortable, points of sail. Advances in design and equipment over the last hundred years have diminished the advantages of the schooner rig. Many schooners sailing today are either reproductions or replicas of famous schooners of old.

Topsail Schooner

A schooner having one or more square-rigged sails on its foremast, but still having gaff-rigged main sails on all masts.

Two-topsail Schooner or Jackass brig

A two-topsail schooner or jackass brig flying a fore course

A schooner having one or more square-rigged sails on its foremast and mainmast, but still having gaff-rigged main sails on all masts.[1]

Brig

Two masts, both square-rigged. The mainmast has a square mainsail and a spanker sail behind it. They are considered very fast and maneuverable, and can reach speeds of up to 11 knots.

Brigantine (UK), Brig (US)

Two masts: a square-rigged foremast and a mainmast with a gaff mainsail and square topsails, with staysails between the masts. For UK terminology it is the gaff-rigged mainsail on a brigantine which distinguishes it from the brig, which is principally square rigged on both masts. In American terminology, this sail plan is often considered still a brig, and the term "brigantine" usualy refers to a vessel with the foremast square-rigged and the mainmast fore-and-aft rigged, without any square sails (a hermaphrodite brig).[2][3]

Hermaphrodite Brig or Schooner Brig

Two masts, square-rigged on the foremast and fore-and-aft rigged on the mainmast.[2]

Snow

Similar to the brig in that it has two masts, both of them square-rigged. Where it differs from the brig is that instead of being attached the main-mast, the spanker sail is attached to a small trysail mast just abaft (behind) the main-mast.

Barque

Three masts or more, square rigged on all except the aftmost mast. Usually three or four masted but five masted barques have been built. Lower-speed, especially downwind, but requiring fewer sailors than a ship. This is a classic slow-cargo ship.

Barquentine or Schooner Barque

A three masted vessel, square rigged on the foremast and fore-and-aft rigged on the main and mizzen masts. Some sailors who have sailed on them say it is a poor-handling compromise between a barque and a ship, though having more speed than a barque or schooner.

Polacre

A three master with a narrow hull; carrying a square-rigged foremast, followed by two lateen sails. The same vessel, if she substituted her square-rigged mast with another lateen rigged one, would be called a xebec.

Fully Rigged Ship

fully rigged ship sail plan
alternate fully rigged ship sail plan

Three or more masts, square rigged on all, usually with stay-sails between masts. The classic ship rig originally had exactly three masts, but four and five masted ships were also built. Occasionally the mizzen mast would have a fore-and-aft sail as its course sail, but in order to qualify as a "fully rigged ship" the vessel would need to have a square-rigged top sail mounted above this (thus distinguishing the fully rigged ship from, say, a barque—see above). The classic sailing warship—the ship of the line—was full rigged in this way, because of high performance on all points of wind. In particular, studding sails or topping sails could be easily added for light airs or high speeds. Square rigs have twice the sail area per mast height compared to triangular sails, and when tuned, more exactly approximate a multiple airfoil, and therefore apply larger forces to the hull. Windage (drag) is more than triangular rigs, which have smaller tip vortices. Therefore, historic ships could not point as far upwind as high performance sloops. However, contemporary marconi rigs (sloops, etc.) were limited in size by the strength of available materials, especially their sails and the running rigging to set them. Ships were not so limited, because their sails were smaller relative to the hull, distributing forces more evenly, over more masts. Therefore, due to their much larger, longer waterline length, ships had much faster hull speeds, and could run down or away from any contemporary sloop or other marconi rig, even if it pointed more upwind. Schooners have a heavier rig and require more ballast than ships, which increases the wetted area and hull friction of a large schooner compared to a ship of the same size. The result is that a ship can run down or away from a schooner of the same hull length. Ships were larger than brigs and brigantines, and faster than barques or barquentines, but required more sailors.

Sail-plan measurements

Sloop rig sail-plan measurements

Every sail-plan has maximum dimensions.[4][5] These maxima are for the largest sail possible and they are defined by a letter abbreviation.

See also

Notes

  1. ↑ http://universalium.academic.ru/145200/main-topsail_schooner
  2. 1 2 http://sailing-ships.oktett.net/brigantine.html
  3. ↑ http://universalium.academic.ru/85396/brigantine
  4. ↑ Sail Measurement Assistance
  5. ↑ Sail Measurement

Further reading

External links

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