The crab claw sail is a

fore-and-aft A fore-and-aft rig is a sailing ship rig with sails set mainly in the median plane of the keel, rather than perpendicular to it, as on a square-rigged vessel. Description Fore-and-aft rigged sails include staysails, Bermuda rigged sails, gaff ...

triangular sail with

spars SPARS was the authorized nickname for the United States Coast Guard (USCG) Women's Reserve. The nickname was derived from the USCG's motto, "—"Always Ready" (''SPAR''). The Women's Reserve was established by law in November 1942 during Wor ...

along upper and lower edges. The crab claw sail was first developed by the

Austronesian peoples The Austronesian people, sometimes referred to as Austronesian-speaking peoples, are a large group of peoples who have settled in Taiwan, maritime Southeast Asia, parts of mainland Southeast Asia, Micronesia, coastal New Guinea, Island Melan ...

by at least 2000 BCE. It is sometimes known as the Oceanic lateen or the Oceanic sprit, even though it is not restricted to

Oceania Oceania ( , ) is a region, geographical region including Australasia, Melanesia, Micronesia, and Polynesia. Outside of the English-speaking world, Oceania is generally considered a continent, while Mainland Australia is regarded as its co ...

, is neither a

lateen A lateen (from French ''latine'', meaning "Latin") or latin-rig is a triangular sail set on a long Yard (sailing) , yard mounted at an angle on the mast (sailing) , mast, and running in a fore-and-aft direction. The Settee (sail), settee can be ...

sail nor a

spritsail The spritsail is a four-sided, fore-and-aft sail that is supported at its highest points by the mast and a diagonally running spar known as the sprit. The foot of the sail can be stretched by a boom or held loose-footed just by its sheets. A ...

, and has an independent older origin.

History

Crab-claw sails were invented by the

Austronesians The Austronesian people, sometimes referred to as Austronesian-speaking peoples, are a large group of peoples who have settled in Taiwan, maritime Southeast Asia, parts of mainland Southeast Asia, Micronesia, coastal New Guinea, Island Melanesi ...

somewhere in

Island Southeast Asia Maritime Southeast Asia comprises the Southeast Asian countries of Brunei, Indonesia, Malaysia, the Philippines, Singapore, and East Timor. The terms Island Southeast Asia and Insular Southeast Asia are sometimes given the same meaning as Mari ...

by at least 2000 BCE. It spread with the Austronesian migration to

Micronesia Micronesia (, ) is a subregion of Oceania, consisting of approximately 2,000 small islands in the Northwestern Pacific Ocean. It has a close shared cultural history with three other island regions: Maritime Southeast Asia to the west, Poly ...

Island Melanesia Island Melanesia is a subregion of Melanesia in Oceania. It is located east of New Guinea island, from the Bismarck Archipelago to New Caledonia.Steadman, 2006. ''Extinction & biogeography of tropical Pacific birds'' See also Archaeology a ...

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

, and

Polynesia Polynesia ( , ) is a subregion of Oceania, made up of more than 1,000 islands scattered over the central and southern Pacific Ocean. The indigenous people who inhabit the islands of Polynesia are called Polynesians. They have many things in ...

. It may have also caused the unique development of

outrigger boat Outrigger boats are various watercraft featuring one or more lateral support floats known as outriggers, which are fastened to one or both sides of the main hull (watercraft), hull. They can range from small dugout (boat), dugout canoes to large ...

technology due to the necessity for stability once crab claw sails were attached to small watercraft. Crab claw sails can be used for double-canoe (

catamaran A catamaran () (informally, a "cat") is a watercraft with two parallel hull (watercraft), hulls of equal size. The wide distance between a catamaran's hulls imparts stability through resistance to rolling and overturning; no ballast is requi ...

single-outrigger Outrigger boats are various watercraft featuring one or more lateral support floats known as outriggers, which are fastened to one or both sides of the main hull. They can range from small dugout canoes to large plank-built vessels. Outrigger b ...

(on the windward side), or double-outrigger boat configurations, in addition to

monohull right A monohull is a type of boat having only one hull, unlike multihulled boats which can have two or more individual hulls connected to one another. Fundamental concept Among the earliest hulls were simple logs, but these were generally unstab ...

s. Crab claw sails are rigged

and can be tilted and rotated relative to the wind. They evolved from "V"-shaped perpendicular

square sail Square rig is a generic type of sail and rigging arrangement in which a sailing vessel's primary driving sails are carried on horizontal spars that are perpendicular (or square) to the median plane of the keel and masts of the vessel. These sp ...

s (a "double sprit") in which the two spars converge at the base of the hull. The simplest form of the crab claw sail (also with the widest distribution) is composed of a triangular sail supported by two light spars (sometimes erroneously called "

sprit The spritsail is a four-sided, fore-and-aft sail that is supported at its highest points by the mast and a diagonally running spar known as the sprit. The foot of the sail can be stretched by a boom or held loose-footed just by its sheets. A sp ...

s") on each side. They were originally mastless, and the entire assembly was taken down when the sails were lowered. There are several distinct types of crab claw rigs, but unlike western rigs, they do not have fixed conventional names. Atlas pittoresque pl 096

The need to propel larger and more heavily laden boats led to the increase in vertical sail. However this introduced more instability to the vessels. In addition to the unique invention of

outrigger An outrigger is a projecting structure on a boat, with specific meaning depending on types of vessel. Outriggers may also refer to legs on a wheeled vehicle that are folded out when it needs stabilization, for example on a crane that lifts he ...

s to solve this, the sails were also leaned backwards and the converging point moved further forward on the hull. This new configuration required a loose "prop" in the middle of the hull to hold the spars up, as well as rope supports on the windward side. This allowed more sail area (and thus more power) while keeping the center of effort low and thus making the boats more stable. The prop was later converted into fixed or removable canted masts where the spars of the sails were actually suspended by a

halyard In sailing, a halyard or halliard is a line (rope) that is used to hoist a ladder, sail, flag or yard. The term "halyard" derives from the Middle English ''halier'' ("rope to haul with"), with the last syllable altered by association with the E ...

from the masthead. This type of sail is most refined in Micronesian

proa The ProA is the German basketball league system, second-tier Sports league, league of professional club basketball in Germany. The league comprises 16 teams. Officially the ProA is part of the ''2. Basketball Bundesliga'', which consists of the t ...

s which could reach very high speeds. These configurations are sometimes known as the "crane sprit" or the "crane spritsail". Micronesian, Island Melanesian, and Polynesian single-outrigger vessels also used this canted mast configuration to uniquely develop shunting, where canoes are symmetrical from front to back and change end-to-end when sailing against the wind. The conversion of the prop to a fixed mast led to the much later invention of the

tanja sail Tanja sail ( Malay: ''layar tanjak'') or tanja rig is a type of sail commonly used by the Austronesian people, particularly in Maritime Southeast Asia. It is also known as the tilted square sail, canted rectangular sail, rectangular balance lug ...

(also known variously and misleadingly as the canted square sail, canted rectangular sail, boomed lugsail, or balance lugsail). Tanja sails were rigged similarly to crab claw sails and also had spars on both the head and the foot of the sails; but they were square or rectangular with the spars not converging into a point. Another evolution of the basic crab claw sail is the conversion of the upper spar into a fixed mast. In

, this gave the sail more height while also making it narrower, giving it a shape reminiscent of crab

pincer Pincer may refer to: *Pincers (tool) *Pincer (biology), part of an animal *Pincer ligand, a terdentate, often planar molecule that tightly binds a variety of metal ions *Pincer (Go), a move in the game of Go *"Pincers!", an episode of the TV series ...

s (hence "crab claw" sail). This was also usually accompanied by the lower spar becoming more curved. Austronesians traditionally made their sails from woven mats of the resilient and salt-resistant

pandanus ''Pandanus'' is a genus of monocots with about 578 accepted species. They are palm-like, dioecious trees and shrubs native to the Old World tropics and subtropics. Common names include pandan, screw palm and screw pine. The genus is classified ...

leaves. These sails allowed Austronesians to embark on long-distance voyaging. In some cases, however, they were one-way voyages. The failure of pandanus to establish populations in

Easter Island Easter Island (, ; , ) is an island and special territory of Chile in the southeastern Pacific Ocean, at the southeasternmost point of the Polynesian Triangle in Oceania. The island is renowned for its nearly 1,000 extant monumental statues, ...

and

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

is believed to have isolated their settlements from the rest of Polynesia. Because of the crab claw sail's more ancient origin, there is also a hypothesis that contact between

Arabs Arabs (, , ; , , ) are an ethnic group mainly inhabiting the Arab world in West Asia and North Africa. A significant Arab diaspora is present in various parts of the world. Arabs have been in the Fertile Crescent for thousands of yea ...

and Austronesians in their Indian Ocean voyages may have influenced the development of the triangular Arabic

sail; and in return Arab square-shaped sails may have influenced the development of the Austronesian rectangular

of western Southeast Asia. Others, however, believe that the tanja sail was an indigenous invention of Southeast Asian Austronesians, though they also believe that the lateen sail may have been introduced to Arab sailors via contact with Austronesian crab claw sails. A third theory however, concludes that lateen sails were originally Mediterranean and that

Portuguese Portuguese may refer to: * anything of, from, or related to the country and nation of Portugal ** Portuguese cuisine, traditional foods ** Portuguese language, a Romance language *** Portuguese dialects, variants of the Portuguese language ** Portu ...

sailors introduced the lateen sail to Asian waters, starting with

Vasco da Gama Vasco da Gama ( , ; – 24 December 1524), was a Portuguese explorer and nobleman who was the Portuguese discovery of the sea route to India, first European to reach India by sea. Da Gama's first voyage (1497–1499) was the first to link ...

's arrival in

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

in 1500. This means that the development of lateen sails in western sailors were not influenced by the crab claw sail. In western

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

, the crab claw sail reappeared as a recent development. Traditionally the people from western Indonesian islands had shifted to the tanja sail, but starting in the 19th century the

Madurese people Madurese people ('' mUH-dOO-rUH''; ; ) are one of the Austronesian-speaking ethnic group native to the Indonesian island of Madura in the Java Sea, off the northeastern coast of Java. They speak their own native Madurese (with diverse varieties ...

developed the lete sail. "''Lete''" actually means lateen, but the existence of ''pekaki'' (lower spar/boom) indicates that the ''layar lete'' is crab claw sail. Modern

wind tunnel A wind tunnel is "an apparatus for producing a controlled stream of air for conducting aerodynamic experiments". The experiment is conducted in the test section of the wind tunnel and a complete tunnel configuration includes air ducting to and f ...

studies of sail types show that crab sail performance improves over

Bermuda rig Bermuda rig, Bermudian rig, or Marconi rig is a type of sailing rig that uses a triangular sail set abaft (behind) the mast. It is the typical configuration for most modern sailboats. Whilst commonly seen in sloop-rigged vessels, Bermuda rig is ...

s, as the

point of sail A point of sail is a sailing craft's direction of travel under sail in relation to the true wind direction over the surface. The principal points of sail roughly correspond to 45° segments of a circle, starting with 0° directly into the wind ...

deviates from close hauled. The configuration has been considered for modern yachts.

Construction

The crab claw sail consists of a sail, approximately an

isosceles triangle In geometry, an isosceles triangle () is a triangle that has two Edge (geometry), sides of equal length and two angles of equal measure. Sometimes it is specified as having ''exactly'' two sides of equal length, and sometimes as having ''at le ...

in shape. The equal length sides are usually longer than the third side, with

along the long sides. Austronesian sails typically have spars along two edges of the sail. This is to distribute the loads of sheets and other point loads on the sail. The traditional and historic mat sails used for Austranesian sails has no reinforcement of the sail material along the edges. Since mat sails are not as strong as other sail materials, such as canvas, it is important that the spars provide the necessary reinforcement of the edges. The crab claw may also traditionally be constructed with curved spars, giving the edges of the sail along the spars a convex shape, while the leech of the sail is often quite concave to keep it stiff on the trailing edge. These features give it its distinct, claw-like shape. Modern crab claws generally have straighter spars and a less convex leech, which gives more sail area for a given length of spar. Spars may taper towards the leech. The structure helps the sail to spill gusts. The crab claw characteristically widens upwards, putting more sail area higher above the ocean, where the wind is stronger and steadier. This increases the

heeling moment Forces on sails result from movement of air that interacts with sails and gives them motive power for sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and sail-powered land vehicles. Similar principles in a rotating ...

: the sails tend to blow the watercraft over. For this reason, crab claws are typically used on

multihull A multihull is a boat or ship with more than one Hull (watercraft), hull, whereas a vessel with a single hull is a monohull. The most common multihulls are catamarans (with two hulls), and trimarans (with three hulls). There are other types, wi ...

s, which resist heeling more strongly. File:Rigging-melanesia-sail.svg, V-shaped

square rig Square rig is a generic type of sail plan, sail and rigging arrangement in which a sailing ship, sailing vessel's primary driving sails are carried on horizontal spar (sailing), spars that are perpendicular (or wikt:square#Adjective, square) to t ...

from

Melanesia Melanesia (, ) is a subregion of Oceania in the southwestern Pacific Ocean. It extends from New Guinea in the west to the Fiji Islands in the east, and includes the Arafura Sea. The region includes the four independent countries of Fiji, Vanu ...

, the direct precursor of crab claw sails File:Sail plan proa steep.svg, "Crane sprit" type crab claw rig of

with a loose prop File:Boracay paraw sailboats 004.jpg, "Crane sprit" type crab claw rig of the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

with a fixed mast File:Sail plan tepukei.svg, Forward-mounted crab claw rig from the Duff Islands File:Rigging-crabclaws2-sail.svg, New Guinea-style crab claw rig with vertical sails File:Rigging-crabclaws3-sail.svg, Hawaiian crab claw rig amalgamating the upper spar into the fixed mast

Shunting

Due to the construction of the sail, a symmetrical boat with a crab claw does not

tack Thermoproteati is a kingdom of archaea. Its synonym, "TACK", is an acronym for Thaumarchaeota (now Nitrososphaerota), Aigarchaeota, Crenarchaeota (now Thermoproteota), and Korarchaeota (now Thermoproteota), the first groups discovered. They ...

, and instead the sail is shunted. In a shunt, the sail is unfixed from the bow, the other side of it is fixed to the stern, and the mast rake is also reversed. After this conversion, the bow ''becomes'' the stern and vice versa. The vessel therefore always has the '' ama'' outrigger (and

sidestay Rigging comprises the system of ropes, cables and chains, which support and control a sailing ship or sail boat's masts and sails. ''Standing rigging'' is the fixed rigging that supports masts including shrouds and stays. ''Running riggi ...

, if there is one) to windward, and has no bad tack, traveling equally well in both directions.

Proa

In a

, the forward intersection of the spars is placed towards the bow. The sail is supported by a short mast attached near the middle of the upper spar, and the forward corner is attached to the hull. The lower spar, or boom, is attached at the forward intersection, but is not attached to the mast. The proa has a permanent windward and leeward side, and exchanges one end for the other when coming about. To tack, or switch directions across the wind, the forward corner of the sail is loosened and then transferred to the opposite end of the boat, a process called ''shunting''. To shunt, the proa's sheet is let out. The joined corner of the spars is then transferred to the opposite end of the boat. While remaining attached to the top of the mast, the upper spar tilts to vertical and beyond as the forward corner moves past the mast and onward to the other end of the boat. Meanwhile, the

mainsheet In sailing, a sheet is a line (rope, cable or chain) used to control the movable corner(s) (clews) of a sail. Terminology In nautical usage the term "sheet" is applied to a line or chain attached to the lower corners of a sail for the purpose ...

is detached and used to rotate the rearward end of the boom through a horizontal half circle. The spar join is then re-attached at the new "forward" end of the boat and the mainsheet is re-tightened at the new "rearward" end.

Tepukei

A shunting rig with the sail propped vertically at the bow, very similar to the proa rig described above.

Non-shunting crab claw

File:Hokule'a.jpg, Hokule'a, a bluewater ''waʻa kaulua'', with curved-spar, curved-leech crab claw sails, in 1976. File:Hokulea2.jpg, Hokule'a with her kaula pe'a (''sail lines'') tightened to partly close her crab-claw sails. The term "crab claw sail" is also used for non-shunting sails that widen upwards. The 'ōpe'a, the upper spar, is braced up so high that it is nearly parallel to the mast (as in a

gunter rig Gunter rig is a configuration of sail and spars used in sailing. It is a Fore-and-aft rig, fore and aft sail set abaft (behind) the mast. The lower half of the luff (front) of the sail is attached to the mast, and the upper half is fastened to ...

). The paepae, the lower spar/boom, points well above the horizontal, unlike the boom of most

s and

gaff rig Gaff rig is a sailing rig (configuration of sails, mast and stays) in which the sail is four-cornered, fore-and-aft rigged, controlled at its peak and, usually, its entire head by a spar (pole) called the ''gaff''. Because of the size and sh ...

s. The two spars can be brought together or pulled apart with control lines.Hōkūle‘a Image Gallery (From 1973)
''archive.hokulea.com'', accessed 12 February 2020 The mast is fixed and stayed.

Gallery

File:Proa1.jpg, Carolinian '' wa'' with crab claw sail File:Sandeq boats in Majene, West Sulawesi, Indonesia.jpg, ''

Sandeq A Sandeq is a type of outrigger sailboat or trimaran used by the Mandarese people for fishing and as a means of transportation between islands. The size of Sandeq varies, with hulls ranging from long and wide. Its carrying capacity ranges fr ...

'' boats in Majene,

West Sulawesi West Sulawesi (), covering a land area of 17,152.99 km2 with its capital at Mamuju, is a province of Indonesia on the western side of Sulawesi (formerly Celebes) island, consisting 6 regencies ('' kabupaten''), namely Polewali Mandar, Ma ...

File:Pirogue Nouvelle Calédonie.JPG, A proa in

New Caledonia New Caledonia ( ; ) is a group of islands in the southwest Pacific Ocean, southwest of Vanuatu and east of Australia. Located from Metropolitan France, it forms a Overseas France#Sui generis collectivity, ''sui generis'' collectivity of t ...

File:Boracay paraw sailboats 015.jpg,

Visayan Visayans ( Cebuano: ''mga Bisayà'' ) are a Philippine ethnolinguistic family group or metaethnicity native to the Visayas, to the southernmost islands south of Luzon, and to a significant portion of Mindanao. They are composed of numerous di ...

paraw Paraw (also spelled ''parao'') are various double outrigger sail boats in the Philippines. It is a general term (similar to the term '' bangka'') and thus can refer to a range of ship types, from small fishing canoes to large merchant lashe ...

'' with a "crane sprit" crab claw sail File:Choris, Krusenstern Islands.jpg, Illustration of a crab claw sail in

Tikehau Tikehau (meaning ''Peaceful Landing'' in TuamotuanOfficial Tikehau Tourism Site< ...

(

Louis Choris Louis Choris (1795–1828) was a German-Russian painter and explorer.Louis Choris
. The ...

, 1816) File:COLLECTIE TROPENMUSEUM Madoerese prauwen Soerabaja TMnr 10010482.jpg, Madurese ''

golekan Golekan is a type of traditional boat from Madura, Indonesia. They once plied as far as Singapore, where they are referred to as Madurese people, Madurese traders. In the present this type of boat is only known locally, especially near Bangkalan ...

'' with crab claw sails File:Anson-Gosse-1750-30.jpg, 1750 illustration of crab claw sail by George Anson

Notes

References

External links

Video "Hot Buoys" Self-Tacking Crab-Claw Trimaran

{{Ancient seafaring Sailing rigs and rigging Austronesian culture