Sail plan

Sailing frigate and her rigging

A sail plan is a set of drawings, usually prepared by a naval architect which shows the various combinations of sail proposed for a sailing ship. Alternatively, as a term of art, it refers to the way such vessels are rigged as discussed below.[1]

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

Star of India showing view of most of her sails, and her standing and running rigging

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 foremast, mainmast and mizzenmast. On ships with fewer than three masts, the tallest is the mainmast. 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 jibs' 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 sailing vessels

Examples of historic rigging for two masted ships

Sailing vessels may be distinguished by:


Sail-plan gallery (detailed descriptions below)
Proa
Proa: single mast with crab claw sail 
Sunfish
Sunfish (sailboat): single unstayed mast with single sail 
Catboat
Catboat: single mast and single sail, usually gaff-rigged 
Lugger
Lugger: two-masted lug rig 
Gunter
Gunter: single fore-and-aft rigged mast in two pieces 
Sloop
Sloop: single fore-and-aft rigged mast and a jib 
Cutter
Cutter (boat): single mast, gaff rigged mainsail and square-rigged topsail, two or more headsails 
Yawl
Yawl: fore-and-aft rigged mainmast and mizzen mast aft of the tiller 
Ketch
Ketch: two fore-and-aft rigged masts, mizzen mast before the tiller 
Schooner
Schooner: two or more fore-and-aft rigged masts, first mast no taller than the second 
Topsail schooner
Topsail schooner: two schooner-rigged masts with one or more square-rigged topsails 
brig
Bilander: two masts, main mast course sail lateen rigged, all others square rigged 
Schooner Brig
Brig: two square-rigged masts and headsails 
Brigantine
Schooner Brig: one square-rigged foremast and one fore-and-aft rigged main mast 
Snow
Brigantine: one square-rigged foremast and hybrid rigged main mast 
Barque
Snow: headsails, two square-rigged masts, and a third smaller 'snow-mast' with a trysail 
Barquentine
Barque: two or more square-rigged masts and headsails with fore-and-aft rigged aftmost mast 
Polacre
Barquentine: two square-rigged mast (fore) and 2 fore-and-aft rigged (main and mizzen) masts 
Fully-rigged
Polacre: one square-rigged main with headsails and two lateen rigged aft masts 
Junk
Fully rigged ship: three or more (all) square-rigged masts and headsails 
Felucca
Junk rig: one or more junk-rigged masts 
Felucca: one to three lateen rigged masts 

Types of sails

Squarish sails

There is no single best type of rig. There are many types of rig because they all have their advantages and disadvantages.

A single loose-footed square sail hung from a yard was likely the oldest form of sail, as woven cloth is initially square. Ancient Egyptian boats had a single square sail with two yards, top and bottom. A lugsail is similar, but the yard is pulled offcenter, making it more weatherly so that it can go more quickly upwind. A settee sail is a lugsail with one very short side. If the lug is so offcenter that one end is attached to the mast, it is a gaff rig. A spritsail is like a gaff, but the "gaff" runs diagonally across the face of the sail and supports the peak of the sail, and is therefor called a sprit. If the "gaff" is bound nearly parallel to the mast, it becomes a gunter rig. If the sail is a triangle strung between the mast and the horizontal boom, it is a Bermuda rig.

Triangular sails

Spars

All of these sails may have a boom along the bottom, or they may have none. A boom-footed sail gives better control of the sail shape, and thus makes the sail more efficient, especially upwind. One of advantages of loose-footed sails is that there is no boom to hit one's head or knock one into the water. Boats without booms are also lighter and cheaper to make.

Some gaff and some junk rigs get in the way of shroud lines strung between the mast and hull. If the mast cannot be held up by shrouds, it must stand up by itself, which makes it heavier, especially on a large boat.

A gunter rig is often used for smaller boats where the mast is frequently taken down; the mast is made short enough to be stored flat inside the boat. The popular Mirror class of racing dinghy is gunter-rigged for this reason.

Lug, lateen and settee sails have an efficient tack and an inefficient tack, in which the sail presses against the mast, spoiling its aerodynamics. Some swing their yards around the mast to make both tacks efficient, but this is difficult with larger sails.

Crab-claws are easily constructible, as they work well when cut from a single flat sheet (they don't need multiple shaped pieces to create their 3-D draft). On a small boat like the Sunfish, their rigging can also be limited to one sheet and one halyard.

Junk rigs, like crab-claws, place no extreme loads anywhere on the sail or rigging, so they can be built using light-weight, weaker, less-expensive materials. The subdivided sails make them easy for a small crew to handle, and they are easy to reef. Junks also customarily have internal water-tight bulkheads, as do modern ships.

Aspect ratio

The sails above vary in shape from square to triangular. A triangular sail has half the surface area of a squarish sail of the same height. For the sails to have the same surface area, the triangular sail must be twice as tall.

There are several disadvantages to a tall rig. Firstly, it makes the boat less stable. If the sails are tall, the wind tends to push the boat over (the center of effort of the sail pushes sideways higher on the mast). A boat is also more tippy if it has a taller mast or heavy spars high up (such as the gaff on a gaff rig). An outrigger, ballast, and/or a long keel is needed to keep the boat upright. Secondly, a taller rig makes it harder to hold the mast onto the boat (with the standing rigging). Generally, taller rigs are more highly-stressed structures than shorter rigs. This makes them more expensive and more fragile for a given strength of material. Stronger, cheaper modern materials are one reason why shorter, squarer rigs are becoming rare.

Why, then, use a tall triangular sail? Because it is more aerodynamic than a squarish one. Downwind, a sail acts like a windsock; the wind just hits and bounces, pushing the boat downwind. But at right angles to the wind, the sail catches the wind and redirects it, letting it sail faster than the wind. Pushing the wind around to a different direction pushes the sailboat off in the opposite direction (modified by the forces from the hull, which are all that stop the boat from blowing away). A sailboat can't sail directly upwind, but by redirecting the wind it can sail nearly upwind. It can then tack in a zigzag to move directly upwind.

A tall, thin sail redirects the wind more smoothly, so it can sail more nearly upwind than a wide sail (it is more weatherly). Sailing a race in a circle, everyone has to go upwind. So other things (like sail area) being equal, the most weatherly boat will win. This is why almost all racing boats have tall, thin sails. They also have deep, heavy keels, or are multihulls, so that they don't tip over, and strong standing rigging, so their masts don't blow off.

Boats with shorter, wider sails have lighter, shallower hulls. They may wait for a favourable wind to avoid sailing upwind. They may go faster than a high-aspect-ratio sailboat when not going upwind; for instance, crab-claws sail extremely well on a beam reach.

Distinctions in nomenclature

European, and especially English, watercraft terminology draws a strong distinction between square-rigged vessels (with square sails hung from yards mounted centrally and horizontally from masts) and fore-and-aft rigged ones (everything else). It is important to note that any other sail (such as a lug or sprit sail), even if it is geometrically square, is not a square sail in the technical sense used in European sail terminology. It is merely a quadrilateral fore-and-aft sail. Vessels are named by the number of square-rigged masts that they have. This is because square-rigged vessels used to be the fastest rig, and more masts were faster.

Any traditional European vessel that really needed speed was square-rigged. Navy sailing vessels, pirates, merchants that needed to escape pirates,and merchant vessels that just needed speed, such as tea clippers, all had towering stacks of smallish square sails. Given a huge crew to control all the sails, they could often outrace the fore-and-aft rigged vessels of the day, even upwind. They needed more tacks, so they had to go further, but they had nearly twice the sail area, so they went more quickly and still got there sooner. A fore-and-aft rigged vessel, with its less sub-divided sails, would break its masts and rigging if it tried to carry the same area of sail and go equally fast. Stronger materials (and winch technology to control large sails) now let fore-and-aft rigged vessels outrace square-rigged ones.

Junk rigs essentially have the stack of sails, but without all the gaps between them. Where the yards controlled the towers of square sails, the battens controlled the junk sail. In East Asia, the largest and the smallest boats traditionally use junk sails, and vessels are not named by sail type, but by region, function, and other characteristics.

Likewise, in the Pacific both large and small sailing vessels traditionally use what are generally called crabclaw sails, although they are of many different types. Other sails are also traditionally used.

In the Middle East, on the east coast of Africa, and as far east as India, lateens and settees were in common use. Ships were named more with regard to purpose than number of masts or type of sail. For instance, feluccas and sambuks were mostly used for fishing and ferrying, dhows are heavy cargo vessels. Xebecs, which also had oars, were used by corsairs to outpace merchant vessels, which were also often xebecs.

Attempts to blend nomenclature, as in the junk diagram to the left above, occur. A ship can be rigged with one of its sails as a junk sail and another as a Bermuda rig without being considered a junk vessel.

Catboat (one mast, one sail)

A catboat is a sailboat with a single mast and single sail; for examples of the variety of catboats, see the section above. 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 for home-built boats uses this simple rig to make "folk-boats".

The term "catboat" is usually qualified by the type of sail, for example "a gaff catboat".

Proa

A proa has one sail, and is thus a catboat, though it is rarely called a catboat. Both ends are alike, and the boat is sailed in either direction, but it has a fixed leeward side and a windward side. The boat is shunted from beam reach to beam reach to change direction, with the wind over the side, a low-force procedure. The bottom corner of the crabclaw sail is moved to the other end, which becomes the bow as the boat sets off back the way it came. The mast usually hinges, adjusting its rake (mast). The proa is a low-stress rig, which can be built with simple tools and low-tech materials, but it is extremely fast. On a beam reach, it may be the fastest simple rig.

In a traditional pacific proa, the outrigger (ama) lies on the windward side of the main hull (vaka), with its weight helping keep the proa upright. The ama is very thin, to punch through waves, smoothing the ride. The first Europeans, building proas from travellers' reports, built Atlantic proas, with the outrigger on the leeward side, with its buoyancy keeping the proa upright.

Sloop (one mast, two sails)

A Bermuda or gaff mainsail lifted by a single mast with a single jib attached to a bowsprit, bent onto the forestay, held taut with a backstay. The mainsail is usually managed with a spar on the underside called a "boom".

A Bermuda-rigged sloop is one of the best racing rigs per square foot of sail area as is it very weatherly, making it faster on upwind 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.

Cutter (one mast, three or more sails)

A small single-masted ship with three or more sails. A common rig is a gaff-rigged mainsail, multiple headsails, and, often, a gaff- or square-rigged topsail above. Sometimes cutters also had an additional square-rigged mainsail when traveling downwind. The mast was normally set amidships, and two or more headsails were set from the mast to the running bowsprit.[4] Considered better than a sloop for light winds; it is also easier to manage, as the sail area is more subdivided.


Two-masted vessels

Lugger

Sailing fifie

A lugger is a two-masted vessel, with for each mast a sail plan similar to a gaff rig. The lug sails it uses, however, do not have gaffs, that attach directly to its masts. Instead, the spars are allowed to move forward and aft of the mast and are managed through a series of lines that attach to the yards and to the corners of the sails. Each 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 are known as fifies, sailing fifies, or herring drifters; they were often used for herring fishing.

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). If square rigged on her mainmast above the course, it is called a "square topsail ketch". 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.

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

This type of vessel has two masts, each made of two spars. The mainmast is rigged exactly like the mainmast of any other schooner (i.e., fore and aft mainsail and gaff rigged topsail) but the foremast, though having the typical schooner's fore and aft rigged mainsail, has above it one or more square rigged topsails. The arrangement requires the ship to have a foremast yard (the lowest) from which no sail hangs. The foremast and all of its sails are comparable to that of a brigantine (see below). If there are square rigged topsails on both masts, then it is called a two topsail schooner or double topsail schooner.[5]

Bilander

The bilander is a two-masted vessel, the foremast carrying square rigs on all of its yards and its taller mainmast having a long lateen mainsail yard with corresponding trapezoidal sail and rig inclined at about 45° with square rigs on the yards above that, the lowermost secured at the corners by a crossjack. The design was popular in the Mediterranean Sea as well as around New England in the first half of the 18th century, but was soon surpassed by better designs. It is considered the forerunner of the brig.[5]

Brig

In American parlance, the brig encompasses three classes of ship: the full-rigged brig (often simply called a "brig"), the hermaphrodite brig, and the brigantine. All American brigs are defined by having exactly two masts that are entirely or partially square rigged. The foremast of each is always entirely square rigged; variations in the taller mainmast are what define the different subtypes [5] (The definition of a brig, brigantine, etc. has been subject to variations in nation and history, however, with much crossover between the classes).

Full-rigged brig

For the full-rigged brig, the foremast and mainmast each has three spars, all of them square rigged. In addition, the mainmast has a small gaff-rigged sail mounted behind ("abaft") the mainmast.

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

On a hermaphrodite brig, also called a "half brig" and a "schooner brig", the main mast carries no yards: it is made in two spars and carries two sails, a gaff mainsail and gaff topsail, making it half schooner and half brig (hence its name). If it also carries one or more square-rigged topsails on the mainmast, it is then considered a "jackass brig".[5] Some authors have asserted that this type of sail plan is that of a brigantine.[6]

Brigantine

Like the hermaphrodite brig, a brigantine also has a main (second) mast made in two spars, and its large mainsail is also fore and aft rigged. However, above this it carries two or three square rigged yards instead of a gaff topsail (the hermaphrodite brig retains the gaff topsail), and carries no square rigged sail at all on its lowermost yard of its mainmast (the full-rigged brig retains a square rigged sail in this position, making it very difficult to visually distinguish at a distance from a brigantine).[5]

Snow

Although superficially similar in appearance to the brig or brigantine, the snow is a much older three masted design which evolved from the larger fully rigged ship. The foremast and mainmast are both squared-rigged, but the fore and aft rigged spanker sail is attached to a small trysail mast (or in modern times a steel cable) stepped directly behind the mainmast. This "snow-mast" allows the gaff to raised unhindered by the mainmast and higher than the main yard, which in turn also allows the snow to fly a main course without complications.

Three-masted vessels

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 than full-rigged ship, especially downwind, but requiring fewer sailors than a full-rigged ship. Optimum rig for transoceanic voyages. This is a classic windjammer rig.

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 (three or more at least partly square-rigged masts)

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.[7][8] These maxima are for the largest sail possible and they are defined by a letter abbreviation.

See also

Notes

  1. ↑ Folkard, Henry Coleman (2012). Sailing Boats from Around the World: The Classic 1906 Treatise. Dover Maritime. Courier Corporation. p. 576. ISBN 9780486311340.
  2. ↑ Perkins, Tom; Dijkstra, Gerard; Navi, Perini; Roberts, Damon (2004), The Maltese Falcon: the realization (PDF), International HISWA Symposium on Yacht Design and Yacht Construction, retrieved 7 September 2016
  3. ↑ http://vaka.org/2017/01/calling-the-wind-of-reunion/
  4. ↑ Nicholas Blake; Richard Lawrence (August 2005). The Illustrated Companion to Nelson's Navy. Stackpole. p. 46. ISBN 978-0-8117-3275-8.
  5. 1 2 3 4 5 John Robinson; George Francis Dow (1922). The Sailing Ships of New England, 1607-1907. Marine Research Society. pp. 28–30.
  6. ↑ John Harper (30 November 2010). Ghostly Tales on Land and Sea. F+W Media. p. 57. ISBN 978-1-4463-5004-1.
  7. ↑ Sail Measurement Assistance
  8. ↑ Sail Measurement

Further reading

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.