A pair of Viper swimfins

Full foot fins

Swimfins, swim fins, fins or flippers are worn on the foot or leg and made from finlike rubber or plastic, to aid movement through the water in water sports activities such as swimming, bodyboarding, bodysurfing, kneeboarding, riverboarding, and various types of underwater diving.

Scuba divers use fins to move through water efficiently, as human feet being very small provide relatively poor thrust, especially when the diver is carrying equipment that increases hydrodynamic drag.^[1][2][3] Very long fins and monofins are used by freedivers as a means of underwater propulsion that does not require high frequency leg movement.

History[link]

Early inventors, including Leonardo da Vinci and Giovanni Alfonso Borelli, toyed with the concept of swimfins.^[4]

Benjamin Franklin made a pair of early swimfins when he was a young boy living in Boston, Massachusetts near the Charles River; they were two thin pieces of wood, about the shape of an art palette, which allowed him to move faster than he usually did in the water.^[5]

Modern swimfins are an invention from the Frenchman Louis de Corlieu, capitaine de corvette (Lieutenant Commander) in the French Navy. In 1914 De Corlieu made a practical demonstration of his first prototype for a group of navy officers, Yves le Prieur among them,^[6] who years later, in 1926, invented an early model of scuba set. De Corlieu left the French Navy in 1924 to fully devote himself to his invention.^[7] In April 1933 he registered a patent (number 767013, which in addition of two fins for the feet included two spoon-shaped fins for the hands) and called this equipment propulseurs de natation et de sauvetage (which can barely be translated as "swimming and rescue impulse device").^[6]

After floundering for years, even producing his fins in his own flat in Paris, De Corlieu finally started mass production of his invention in France in 1939. The same year he rented a licence to Owen P. Churchill for mass production in the United States. To sell his fins in the USA Owen Churchill changed the French De Corlieu's name (propulseurs) to "swimfins", which is still nowadays the current English name. Churchill presented his fins to the US Navy, who decided to acquire them for its Underwater Demolition Team (UDT). American UDT and British COPP frogmen (COPP: Combined Operations Pilotage Parties) used the "Churchill fins" during all prior underwater deminings, allowing this way in 1944 the Normandy landings. During years after World War II had ended, De Corlieu spent time and efforts struggling into civil procedures, demanding others for patent infringement.^[8]

In Britain, Dunlop made frogman's fins for World War II, but after the war saw no market for them in peacetime, and, after the first supply of war-surplus frogman's kit was used up, the British public had no access to swimfins (except for home-made attempts such as gluing marine plywood to plimsolls), until Oscar Gugen began importing swimfins and swimming goggles from France.^[4]

In 1946 Lillywhites imported about 1100 pairs of swimfins; they all sold in under 3 months.^[9]

In 1948 Luigi Ferraro, collaborating with the Italian diving equipment company Cressi-sub, designed the first full-foot fin, the Rondine, named after the Italian word for swallow. A distinctive feature of Cressi's continuing Rondine full-foot fin line is the embossed outline of the bird on the foot pockets and the blades.

In 1949 Ivor Howitt or a friend of his mailed to the Dunlop Rubber Company for swimfins; Dunlop answered that they had no plans to make swimfins and saw no use for them in peacetime. Howitt made his own swimfins with innertube rubber stretched across a frame of stiff rubber tube.

Types[link]

Cressi-sub vented paddle fin Beuchat Closed-heel Jetfins Beuchat Open-heel adjustable Jetfins Long bladed open heel fin with moderately stiff plastic blade A freediver using a monofin

Types of fins have evolved to address the unique requirements of each community using them. Scuba divers, in particular, need large wide fins to overcome the water resistance caused by their diving equipment; snorkelers need lightweight flexible fins; ocean swimmers, bodysurfers, and lifeguards favor smaller designs that stay on their feet when moving through large surf and that make walking on the beach less awkward. In general there are two main groups of fins; full foot and open heel. Full foot fins fit like a shoe, and are designed to be worn over bare feet. If a larger size is chosen, however, full-foot fins can also be worn over socks and thin-soled booties. They are commonly used for surface swimming, and are in non adjustable sizes. Open heel have a foot pocket with an open heel area, and the fin is held to the foot by springs or straps. They can be worn over boots, and are common in diving. Many companies design fins with the same fin architecture but a choice of heel type. Other, more specific design trends are listed below.

Common types[link]

Paddle fins[link]

These are the most basic fins; a pair of simple stiff plastic, composite, or rubber blades that work as extensions of the feet while kicking. Some paddle fins have channels and grooves to improve power and efficiency though it has been shown that the desired effect does not occur.^[3][10] Paddle fins are widely believed to be the most versatile and have improved swimming economy in men.^[1][11] Tests in women showed a more flexible fin to be more economical, most likely due to lower leg power.^[3][12]

Vented fins[link]

Vented fins were first designed in 1964 by Georges Beuchat and commercialised as Jetfins. The Jetfin tradename and design were sold to Scubapro in the 1970s. This style of fin is strongly favored by technical divers that use a frog kick allowing a high degree of control but sacrifice speed for low oxygen consumption.^{[citation needed]} Vented fins are generally stiff paddle fins that have vents at the base of the foot pocket. The vents are intended to allow for the passage of water during the recovery stroke, but prevent passage during power strokes due to the blade angle, attempting to lessen effort during recovery and improve kick efficiency. A review and study by Pendergast et al in 2003 concluded that vented fins did not improve economy, implying that water does not pass through the vents.^[1] There is a risk of objects catching in the vents.

Split fins[link]

Some swimfins have the end of the blade split. The manufacturers claim that split fins operate similarly to a propeller, by creating lift forces to move the swimmer forwards.^[13] The claim is that water flowing toward the center of the fin's "paddle" portion also gains speed as it focuses, creating a "suction" force.^[13] A 2003 study by Pendergast et al called this into question by showing that there was no significant change in performance for a particular split fin design when the split was taped over.^[1] The technology used in most commercial split fin designs is patented by the industrial design firm Nature's Wing, and is used under license.^[14]

Freediving fins[link]

These are very similar to paddle fins, except they are far longer, and designed to work with slow stiff-legged kicks that claims to conserve energy. The vast majority are made in the "full-foot" design with very rigid footpockets, which serves to reduce weight and maximize power transfer from the leg into the fin. Freediving fins are commonly made of plastic, but are also often made from materials such as fiberglass and carbon fiber.

Monofins[link]

A monofin is typically used in finswimming and free-diving. It consists of a single surface attached to footpockets for both the free-diver's feet. Monofins can be made of glass fibre or carbon fibre. The diver's muscle power and swimming style, and the type of activity the monofin is used for, determine the choice of size, stiffness, and materials.

Less usual types[link]

Open and closed heel fins are predominant, but there is a range of fins that have specialised blade attachment architecture. These include (these names are tradenames):

Delfins[link]

The Mor-Fin Corporation produces "delfins", which are swimfins that end short and to the end is attached a shape like a fish's forked homocercal caudal fin. The entire fin is based on the anatomy of various marine animals.^[15]

Force fins[link]

"Force Fin" is the trademark for fins designed, developed, manufactured and distributed by Bob Evans Designs, Inc.^[16] They are distinguished by an open foot pocket, that encloses only the instep, leaving the toes free so the foot can flex.^[17]

Shinfins[link]

These fins are attached to the ankle and rest against the (anatomically) upper side of the foot. The manufacturers claim this avoids leg cramps and reduces foot strain.^[18]

Flipfins[link]

Flipfins in use by frogmen attacking in a harbor, for better mobility on land

Flipfins are a open-heel swimfin designed to allow easy walking on land. Its blade and foot part are separate: the blade hinges onto the foot part at each side, roughly on the level of the metatarsal heads, and when swimming is held in line by a clip on the front of the foot part. On land or when wading the blade can be unclipped and hinged vertically so it does not interfere with walking.^[19][20]

Breast stroke fins[link]

Breast stroke fins are optimized for use with the breaststroke.

• 

  Swim fin strap attacment with simple rubber strap and wire buckle

• 

  Swim fin strap attachment with swivelling plastic buckle and clip

• 

  Aftermarket stainless steel spring fin strap attached with long D-shackles for security

• 

  Open heel fin with stainless steel spring strap with rubber padding

Training[link]

Divers are initially taught to fin with legs straight, without excess bending of the knee, the action coming from the hips;^[21] a leg action with much knee bending like riding a bicycle is inefficient and is a common fault with divers who have not learned properly how to fin swim. Fins with differing characteristics (e.g. stiffness) may be preferred, depending on the application,^[22] and divers may have to learn a modified finning style to match.

The upper limit of a diver's fin-kick thrust force using a stationary-swimming ergometer was shown to be 64 newtons (14 lbf).^[23] The maximum thrust averaged over 20 seconds against a strain gauge has been measured as high as 192 newtons (43 lbf).^[1] Resistive respiratory muscle training improves and maintains endurance fin swimming performance in divers.^[24]

See also[link]

Underwater diving portal

• Human swimming
• PowerSwim, a device somewhat like two pairs of long thin airplane wings fastened to a scuba diver's hips and legs
• Diving equipment
• Scuba equipment
• Finswimming

References[link]

External links[link]

Media related to Swimfins at Wikimedia Commons

• Swim Fins, A comprehensive site on swimming fins, including technical information on swim training and cardiovascular exercise using fins.

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Swimmers redirects here. For other meanings see Swimmer (disambiguation).

Look up swim in Wiktionary, the free dictionary.

Swim or SWIM may refer to:

Movement and sport[link]

• Aquatic locomotion, the act of biologically propelled motion through a liquid medium
• Human swimming, the useful or recreational activity of movement through water
• Swimming (sport), the competitive sport of swimming

SWIM[link]

• Semantic Wiki Information Management, a subcommittee of the Semantic Interoperability Community of Practice (SICoP)
• System Wide Information Management, a technology to help provide data sharing of Air Traffic Management system information
• Surface Water Improvement and Management Program, a Florida state program to improve water quality.
• Someone Who Isn't Me, on internet forums.

Music[link]

• swim ~, a record label founded by Wire guitarist and singer Colin Newman, and Minimal Compact bass player and singer Malka Spigel
• Swim (Caribou album), a 2010 album by Caribou
• Swim (EP), a 1996 EP by the band Feeder, later re-released as an 11 track album
• Swim, a 2008 album from indie band Whispertown 2000
• "Swim" (song), a 2003 song by the alternative rock band Fishbone
• "Swim", a song from Madonna's 1998 album Ray of Light
• "Swim", a song from Jack's Mannequin's 2008 album The Glass Passenger

See also[link]

• Swimming (disambiguation)
• Swimmers (disambiguation)
• All pages beginning with "swim"
• All pages with titles containing "swim"

This disambiguation page lists articles associated with the same title. If an internal link led you here, you may wish to change the link to point directly to the intended article.

Arrow fletches are a type of fin.

A fin is a surface used for stability and/or to produce lift and thrust or to steer while traveling in water, air, or other fluid media, (in other words, a foil (fluid mechanics)). The first use of the word was for the limbs of fish, but has been extended to include other animal limbs and man-made devices. Fins, as with other foils, operate in fluids such as water or air.

Spotted Dolphin The pectoral fin and dorsal fin of the dolphin contribute to its agility and speed in the water. Its tail is also recognizable as a fin. The pectoral fins are movable and used in maneuvering; the dorsal fin is fixed and contributes stability, and the tail is used for propulsion, as well as maneuvering.

Fins are seen both in nature and in manmade iterations.

Swimming water animals such as fish and cetaceans actively use pectoral fins for maneuvering, and dorsal fins contribute stability as the animal swims, propelling and maneuvering with its tail, itself recognizable as a fin.

The fin on fixed-wing aircraft is known as a vertical stabilizer. Fins are also seen used as e.g., fletching on arrows and at the rear of some bombs, missiles, rockets, and self-propelled torpedoes. These are typically "planar" (shaped like small wings), although grid fins are sometimes used in specialized cases.

Examples of fins include:

• Propellers usually have a number of fins that work to translate torquing force to lateral thrust, thus propelling a ship. These are also called blades. In the case of high power application it is important to avoid cavitation, caused by excessive negative pressure, as this can cause noise, a loss of power, and damage to the propeller.

• For scuba divers' fins, see swimfin.

Surfboard fins[link]

In surfing, there are two major types of (typically stationary) surfboard fins (hydrofoils), and a host of illustrative issues.

Both a skeg and "rail fins" stabilize the motion of the surfboard. They also contribute to the desired effect of converting the (kinetic energy) push of the sloped wave face combined with the rider's mass on the sloped wave face (potential energy) into redirected energy - lift (lift (physics)) - the surfer deflects his surfboard and fins off the water of the wave face (and/or vice-versa) to make forward progress across the wave face, or "down the line," that is, parallel to the wave crest and beach - riding parallel to the crest (perpendicular to the pull of gravity down the wave's slope) in this way is known as "trimming." Lift (aka "drive") from the board and its fin(s) is what enables all maneuvers in surfing.

A "skeg" (an upright, streamlined, often raked keel) typically denotes one centrally-mounted stabilizer foil mounted perpendicularly to the riding surface, at the rear of the surfboard.

Smaller surfboard fins mounted near the edge (or "rail") of the surfboard are known as "rail fins" and are seen in multi-fin arrangements (often in combination with a similarly-sized central fin further back on the board). Rail fins enable high-performance surfing, and are most often "single-foiled," with one flat side and one "foiled" side, as seen on an airfoil, for greater lift.

A fin configuration with fins near the edge of the board stabilizes and contributes lift during turning maneuvers, which contributes to the board's ability to "hold" during turning maneuvers. Rail fins are often seen in addition to a central fin, but can be used without a central fin as well. Some of the most popular multi-fin configurations use two rail fins (a "twin-fin"), two rail fins plus a similar-sized central fin mounted further back (e.g. a "Thruster"), or four fins (a "quad"). Rail fins are more or less engaged by the rider's heel and toes as they lean in the desired direction of their turn. As the rider does so, an "inside" rail fin sinks deeper and its angle of attack is increased, as is its lift-induced drag. Rail fins also add lift (known as "drive") in trim and with greater holding ability, enable steeper wave faces to be ridden and higher speed "down the line."

Rail fins are typically "toed-in," that is, the leading edge of the fins are oriented toward the centerline of the surfboard, which decreases the angle of attack in trim, which makes it easier to initiate turns. "Toeing in" rail fins also adds drag on the "outside" fin, as its angle of attack is negative during trim or in a turn. These combined factors of toed-in rail fins cause several issues: drag on a toed-in outside rail fin can slow the board down in trim, but it can also give a braking effect during turns that is useful. The inside rail fin (and the board itself) can be "pumped," attacked and re-attacked, by swerving up and down the face, causing acceleration down the line, or similarly pumped to achieve a desired trajectory through a multi-stage turn. At higher speeds, the drag off toed-in rail fins can cause surfboards to oscillate and become unstable - a phenomenon known as "speed wobbles

Most surfboards intended for larger waves are longer (to increase hull speed for paddling, wave-catching, and surfing), and as most shapers orient the rail fins toward the nose of the board, a longer board inherently results in reduced toe-in of rail fins, therefore less negative angle of attack, less oscillation, greater stability, and higher speeds. Rail fins also typically have some degree of "cant," that is, are tilted out toward the rail they are adjacent to. This is a significant additional factor in lift at various attitudes, drag, and performance, as are the variables of other foils - including flexibility, thickness, and planform. Rail fins evolved into being and surged into popularity as riders (Simon Anderson, most famously) sought a solution to two major performance issues of a central "single" fin - both related to engagement of the foil: For one, a centrally-mounted fin is tilted up out of the water as the board is leaned over, and thus it loses more and more of its lift as the lean angle increases - if the lean angle is acute enough, the fin's tip can be the only area left in the water; the tip may then rapidly stall and, having lost its lift, become disengaged from the water, leaving the board's bottom as the only control surface still operating. Before rail fins became (extremely) popular, this tendency of "single fins" led to riders "nursing" turns - this tendency was a significant limiting factor on performance. The enhanced hold offered by rail fins during turning led to more types of maneuvers being possible. The other major issue leading to rail fins' use is the fact that a rider can use the lift near the rail to increase speed and performance on smaller waves due to the above effects and abilities of these foils. ^[1]

In Windsurfing, a derivative of traditional surfing, skegs are also often used as a central stabilizing fin (hydrofoil) located at the rear of the board. A windsurfer's skeg also has the effect of producing lift, which allows the rider to direct the craft laterally against the lift the sail (itself an airfoil) produces. The skeg has undergone numerous phases of development and, as with other foils, its design is determined by the balance of the pressures it experiences in use, including lift, drag (physics), ventilation and stall (flight).

References[link]