Surfing

About three to five thousand years ago, cultures in ancient Peru surfed on reed watercraft for fishing.[6][7] The Moche culture used the caballito de totora (little horse of totora), with archaeological evidence showing its use around 200 CE.[8] An early description of the Inca surfing in Callao was documented by Jesuit missionary José de Acosta in his 1590 publication Historia natural y moral de las Indias, writing:[9]

It is true to see them go fishing in Callao de Lima, was for me a thing of great recreation, because there were many and each one in a balsilla caballero, or sitting stubbornly cutting the waves of the sea, which is rough where they fish, they looked like the Tritons, or Neptunes, who paint upon the water.

In July 1885, three teenage Hawaiian princes took a break from their boarding school, St. Mathew's Hall in San Mateo, and came to cool off in Santa Cruz, California. There, David Kawānanakoa, Edward Keliʻiahonui and Jonah Kūhiō Kalanianaʻole surfed the mouth of the San Lorenzo River on custom-shaped redwood boards, according to surf historians Kim Stoner and Geoff Dunn.[10] In 1890, the pioneer in agricultural education John Wrightson reputedly became the first British surfer when instructed by two Hawaiian students at his college.[11][12][13]

George Freeth (8 November 1883 – 7 April 1919) is often credited as being the "Father of Modern Surfing". He is thought to have been the first modern surfer.

In 1907, the eclectic interests of the land baron Henry E. Huntington brought the ancient art of surfing to the California coast. While on vacation, Huntington had seen Hawaiian boys surfing the island waves. Looking for a way to entice visitors to the area of Redondo Beach, where he had heavily invested in real estate, he hired a young Hawaiian to ride surfboards. George Freeth decided to revive the art of surfing, but had little success with the huge 500 cm (16 ft) hardwood boards that were popular at that time. When he cut them in half to make them more manageable, he created the original "Long board", which made him the talk of the islands. To the delight of visitors, Freeth exhibited his surfing skills twice a day in front of the Hotel Redondo. Another native Hawaiian, Duke Kahanamoku, spread surfing to both the U.S. and Australia, riding the waves after displaying the swimming prowess that won him Olympic gold medals in 1912 and 1920.

In 1975, a professional tour started.[14] That year Margo Oberg became the first female professional surfer.[14]

The geometry of tube shape can be represented as a ratio between length and width.

Tube shape is defined by length to width ratio. A perfectly cylindrical vortex has a ratio of 1:1. Other forms include:

• Square: <1:1
• Round: 1-2:1
• Almond: >2:1

Peel or peeling off as a descriptive term for the quality of a break has been defined as "a fast, clean, evenly falling curl line, perfect for surfing, and usually found at pointbreaks." [16]

Tube speed is the rate of advance of the break along the length of the wave, and is the speed at which the surfer must move along the wave to keep up with the advance of the tube.[17] Tube speed can be described using the peel angle and wave celerity. Peel angle is the angle between the wave front and the horizontal projection of the point of break over time, which in a regular break is most easily represented by the line of white water left after the break. A break that closes out, or breaks all at once along its length, leaves white water parallel to the wave front, and has a peel angle of 0°. This is unsurfable as it would require infinite speed to progress along the face fast enough to keep up with the break. A break which advances along the wave face more slowly will leave a line of new white water at an angle to the line of the wave face.[17][18]

${\displaystyle V_{s}={\frac {c}{sin\alpha }}}$[17]

Where:

${\displaystyle V_{s}=}$velocity of surfer along the wave face

${\displaystyle c=}$wave celerity (velocity in direction of propagation)

${\displaystyle \alpha =}$peel angle

In most cases a peel angle less than 25° is too fast to surf.[17]

• Fast: 30°
• Medium: 45°
• Slow: 60°

The type of break depends on shoaling rate. Breaking waves can be classified as four basic types: spilling (ξ_b<0.4), plunging (0.4<ξ_b<2), collapsing (ξ_b>2) and surging (ξ_b>2), and which type occurs depends on the slope of the bottom.[17]

Waves suitable for surfing break as spilling or plunging types, and when they also have a suitable peel angle, their value for surfing is enhanced. Othe factors such as wave height and period, and wind strength and direction can also influence steepness and intensity of the break, but the major influence on the type and shape of breaking waves is determined by the slope of the seabed before the break. The breaker type index and Iribarren number allow classification of breaker type as a function of wave steepness and seabed slope.[17]

The value of good surf in attracting surf tourism has prompted the construction of artificial reefs and sand bars. Artificial surfing reefs can be built with durable sandbags or concrete, and resemble a submerged breakwater. These artificial reefs not only provide a surfing location, but also dissipate wave energy and shelter the coastline from erosion. Ships such as Seli 1 that have accidentally stranded on sandy bottoms, can create sandbanks that give rise to good waves.[19]

An artificial reef known as Chevron Reef was constructed in El Segundo, California in hopes of creating a new surfing area. However, the reef failed to produce any quality waves and was removed in 2008. In Kovalam, South West India, an artificial reef has successfully provided the local community with a quality lefthander, stabilized coastal soil erosion, and provided good habitat for marine life.[20] ASR Ltd., a New Zealand-based company, constructed the Kovalam reef and is working on another reef in Boscombe, England.

Surfing a stationary, artificial wave in Southern California

Even with artificial reefs in place, a tourist's vacation time may coincide with a "flat spell", when no waves are available. Completely artificial Wave pools aim to solve that problem by controlling all the elements that go into creating perfect surf, however there are only a handful of wave pools that can simulate good surfing waves, owing primarily to construction and operation costs and potential liability. Most wave pools generate waves that are too small and lack the power necessary to surf. The Seagaia Ocean Dome, located in Miyazaki, Japan, was an example of a surfable wave pool. Able to generate waves with up to 3 m (10 ft) faces, the specialized pump held water in 20 vertical tanks positioned along the back edge of the pool. This allowed the waves to be directed as they approach the artificial sea floor. Lefts, Rights, and A-frames could be directed from this pump design providing for rippable surf and barrel rides. The Ocean Dome cost about $2 billion to build and was expensive to maintain.[21] The Ocean Dome was closed in 2007. In England, construction is nearing completion on the Wave,[22] situated near Bristol, which will enable people unable to get to the coast to enjoy the waves in a controlled environment, set in the heart of nature.

There are two main types of artificial waves that exist today. One being artificial or stationary waves which simulate a moving, breaking wave by pumping a layer of water against a smooth structure mimicking the shape of a breaking wave. Because of the velocity of the rushing water, the wave and the surfer can remain stationary while the water rushes by under the surfboard. Artificial waves of this kind provide the opportunity to try surfing and learn its basics in a moderately small and controlled environment near or far from locations with natural surf.

The Glossary of surfing includes some of the extensive vocabulary used to describe various aspects of the sport of surfing as described in literature on the subject.[23][24] In some cases terms have spread to a wider cultural use. These terms were originally coined by people who were directly involved in the sport of surfing.

Ocean waves are defined as a collection of dislocated water parcels that undergo a cycle of being forced past their normal position and being restored back to their normal position.[30] Wind caused ripples and eddies form waves that gradually gain speed and distance (fetch). Waves increase in energy and speed, and then become longer and stronger.[31] The fully developed sea has the strongest wave action that experiences storms lasting 10-hours and creates 15 meter wave heights in the open ocean.[30]

The waves created in the open ocean are classified as deep-water waves. Deep-water waves have no bottom interaction and the orbits of these water molecules are circular; their wavelength is short relative to water depth and the velocity decays before the reaching the bottom of the water basin.[30] Deep water waves are waves in water depths greater than half their wavelengths. Wind forces waves to break in the deep sea.

Deep-water waves travel to shore and become shallow water waves when the water depth is less than half of their wavelength, and the wave motion becomes constrained by the bottom, causing the orbit paths to be flattened to ellipses. The bottom exerts frictional drag on the bottom of the wave, which decreases the celerity (or the speed of the wave form), and causes refraction. Slowing the wave forces it to shorter which increases the height and steepness, and the top (crest) falls because the velocity of the top of the wave becomes greater than the velocity of the bottom of the wave where the drag occurs.[30]

The surf zone is place of convergence of multiple waves types creating complex wave patterns. A wave suitable for surfing results from maximum speeds of 5 meters per second. This speed is relative because local onshore winds can cause waves to break.[31] In the surf zone, shallow water waves are carried by global winds to the beach and interact with local winds to make surfing waves.[31][32]

Different onshore and off-shore wind patterns in the surf zone create different types of waves. Onshore winds cause random wave breaking patterns and are more suitable for experienced surfers.[31][32] Light offshore winds create smoother waves, while strong direct offshore winds cause plunging or large barrel waves.[31] Barrel waves are large because the water depth is small when the wave breaks. Thus, the breaker intensity (or force) increases, and the wave speed and height increase.[31] Off-shore winds produce non-surfable conditions by flattening a weak swell. Weak swell is made from surface gravity forces and has long wavelengths.[31][33]

Surfing waves can be analyzed using the following parameters: breaking wave height, wave peel angle (α), wave breaking intensity, and wave section length. The breaking wave height has two measurements, the relative heights estimated by surfers and the exact measurements done by physical oceanographers. Measurements done by surfers were 1.36 to 2.58 times higher than the measurements done by scientists. The scientifically concluded wave heights that are physically possible to surf are 1 to 20 meters.[31]

The wave peel angle is one of the main constituents of a potential surfing wave. Wave peel angle measures the distance between the peel-line and the line tangent to the breaking crest line. This angle controls the speed of the wave crest. The speed of the wave is an addition of the propagation velocity vector (Vw) and peel velocity vector (Vp), which results in the overall velocity of the wave (Vs).[31]

Wave breaking intensity measures the force of the wave as it breaks, spills, or plunges (a plunging wave is termed by surfers as a "barrel wave"). Wave section length is the distance between two breaking crests in a wave set. Wave section length can be hard to measure because local winds, non-linear wave interactions, island sheltering, and swell interactions can cause multifarious wave configurations in the surf zone.[31]

The parameters breaking wave height, wave peel angle (α), and wave breaking intensity, and wave section length are important because they are standardized by past oceanographers who researched surfing; these parameters have been used to create a guide that matches the type of wave formed and the skill level of surfer.[31]

Table 1 shows a relationship of smaller peel angles correlating with a higher skill level of surfer. Smaller wave peel angles increase the velocities of waves. A surfer must know how to react and paddle quickly to match the speed of the wave to catch it. Therefore, more experience is required to catch a low peel angle waves. More experienced surfers can handle longer section lengths, increased velocities, and higher wave heights.[31] Different locations offer different types of surfing conditions for each skill level.

A surf break is an area with an obstruction or an object that causes a wave to break. Surf breaks entail multiple scale phenomena. Wave section creation has micro-scale factors of peel angle and wave breaking intensity. The micro-scale components influence wave height and variations on wave crests. The mesoscale components of surf breaks are the ramp, platform, wedge, or ledge that may be present at a surf break. Macro-scale processes are the global winds that initially produce offshore waves. Types of surf breaks are headlands (point break), beach break, river/estuary entrance bar, reef breaks, and ledge breaks.[31]

A headland or point break interacts with the water by causing refraction around the point or headland. The point absorbs the high frequency waves and long period waves persist, which are easier to surf. Examples of locations that have headland or point break induced surf breaks are Dunedin (New Zealand), Raglan (New Zealand), Malibu (California), Rincon (California), and Kirra (Australia).[31]

A group of surfers surfing a beach break in Juno Beach, Florida.

A beach break happens where waves break from offshore waves, and onshore sandbars and rips. Wave breaks happen successively at beach breaks. Example locations are Tairua and Aramoana Beach (New Zealand) and the Gold Coast (Australia).[31]

A river or estuary entrance bar creates waves from the ebb tidal delta, sediment outflow, and tidal currents. An ideal estuary entrance bar exists in Whangamata Bar, New Zealand.[31]

A reef break is conducive to surfing because large waves consistently break over the reef. The reef is usually made of coral, and because of this, many injuries occur while surfing reef breaks. However, the waves that are produced by reef breaks are some of the best in the world. Famous reef breaks are present in Padang Padang (Indonesia), Pipeline (Hawaii), Uluwatu (Bali), and Teahupo'o (Tahiti).[31][34] When surfing a reef break, the depth of the water needs to be considered as surfboards have fins on the bottom of the board.

A ledge break is formed by steep rocks ledges that makes intense waves because the waves travel through deeper water then abruptly reach shallower water at the ledge. Shark Island, Australia is a location with a ledge break. Ledge breaks create difficult surfing conditions, sometimes only allowing body surfing as the only feasible way to confront the waves.[31]

Jetties are added to bodies of water to regulate erosion, preserve navigation channels, and make harbors. Jetties are classified into four different types and have two main controlling variables: the type of delta and the size of the jetty.[35]

The first classification is a type 1 jetty. This type of jetty is significantly longer than the surf zone width and the waves break at the shore end of the jetty. The effect of a Type 1 jetty is sediment accumulation in a wedge formation on the jetty. These waves are large and increase in size as they pass over the sediment wedge formation. An example of a Type 1 jetty is Mission Beach, San Diego, California. This 1000-meter jetty was installed in 1950 at the mouth of Mission Bay. The surf waves happen north of the jetty, are longer waves, and are powerful. The bathymetry of the sea bottom in Mission Bay has a wedge shape formation that causes the waves to refract as they become closer to the jetty.[35] The waves converge constructively after they refract and increase the sizes of the waves.

A type 2 jetty occurs in an ebb tidal delta, a delta transitioning between high and low tide. This area has shallow water, refraction, and a distinctive seabed shapes that creates large wave heights.[35]

An example of a type 2 jetty is called "The Poles" in Atlantic Beach, Florida. Atlantic Beach is known to have flat waves, with exceptions during major storms. However, "The Poles" has larger than normal waves due to a 500-meter jetty that was installed on the south side of the St. Johns. This jetty was built to make a deep channel in the river. It formed a delta at "The Poles". This is special area because the jetty increases wave size for surfing, when comparing pre-conditions and post-conditions of the southern St. Johns River mouth area.[35]

The wave size at "The Poles" depends on the direction of the incoming water. When easterly waters (from 55°) interact with the jetty, they create waves larger than southern waters (from 100°). When southern waves (from 100°) move toward "The Poles", one of the waves breaks north of the southern jetty and the other breaks south of the jetty. This does not allow for merging to make larger waves. Easterly waves, from 55°, converge north of the jetty and unite to make bigger waves.[35]

A type 3 jetty is in an ebb tidal area with an unchanging seabed that has naturally created waves. Examples of a Type 3 jetty occurs in “Southside” Tamarack, Carlsbad, California.[35]

A type 4 jetty is one that no longer functions nor traps sediment. The waves are created from reefs in the surf zone. A type 4 jetty can be found in Tamarack, Carlsbad, California.[35]

Rip currents are fast, narrow currents that are caused by onshore transport within the surf zone and the successive return of the water seaward.[36][37] The wedge bathymetry makes a convenient and consistent rip current of 5–10 meters that brings the surfers to the “take off point” then out to the beach.[35]

Oceanographers have two theories on rip current formation. The wave interaction model assumes that two edges of waves interact, create differing wave heights, and cause longshore transport of nearshore currents. The Boundary Interaction Model assumes that the topography of the sea bottom causes nearshore circulation and longshore transport; the result of both models is a rip current.[36]

Rip currents can be extremely strong and narrow as they extend out of the surf zone into deeper water, reaching speeds from 0.5 m/s (1.6 ft/s) and up to 2.5 m/s (8.2 ft/s),[37][38] which is faster than any human can swim. The water in the jet is sediment rich, bubble rich, and moves rapidly.[37] The rip head of the rip current has long shore movement. Rip currents are common on beaches with mild slopes that experience sizeable and frequent oceanic swell.[38]

A longer surfboard of 300 cm (10 ft) causes more friction with the water; therefore, it will be slower than a smaller and lighter board with a length of 180 cm (6 ft). Longer boards are good for beginners who need help balancing. Smaller boards are good for more experienced surfers who want to have more control and maneuverability.[33]

When practicing the sport of surfing, the surfer paddles out past the wave break to wait for a wave. When a surfable wave arrives, the surfer must paddle extremely fast to match the velocity of the wave so the wave can accelerate him or her.[33]

When the surfer is at wave speed, the surfer must quickly pop up, stay low, and stay toward the front of the wave to become stable and prevent falling as the wave steepens. The acceleration is less toward the front than toward the back. The physics behind the surfing of the wave involves the horizontal acceleration force (F·sinθ) and the vertical force (F·cosθ=mg). Therefore, the surfer should lean forward to gain speed, and lean on the back foot to brake. Also, to increase the length of the ride of the wave, the surfer should travel parallel to the wave crest.[33]

Surfing, like all water sports, carries the inherent risk of drowning.[39] Anyone at any age can learn to surf, but should have at least intermediate swimming skills. Although the board assists a surfer in staying buoyant, it can become separated from the user.[40] A leash, attached to the ankle or knee, can keep a board from being swept away, but does not keep a rider on the board or above water. In some cases, possibly including the drowning of professional surfer Mark Foo, a leash can even be a cause of drowning by snagging on a reef or other object and holding the surfer underwater.[41] By keeping the surfboard close to the surfer during a wipeout, a leash also increases the chances that the board may strike the rider, which could knock him or her unconscious and lead to drowning. A fallen rider's board can become trapped in larger waves, and if the rider is attached by a leash, he or she can be dragged for long distances underwater.[41] Surfers should be careful to remain in smaller surf until they have acquired the advanced skills and experience necessary to handle bigger waves and more challenging conditions. However, even world-class surfers have drowned in extremely challenging conditions.[42]

A surfer exiting a closeout

Under the wrong set of conditions, anything that a surfer's body can come in contact with is a potential hazard, including sand bars, rocks, small ice, reefs, surfboards, and other surfers.[43] Collisions with these objects can sometimes cause injuries such as cuts and scrapes and in rare instances, death.

A large number of injuries, up to 66%,[44] are caused by collision with a surfboard (nose or fins). Fins can cause deep lacerations and cuts,[45] as well as bruising. While these injuries can be minor, they can open the skin to infection from the sea; groups like Surfers Against Sewage campaign for cleaner waters to reduce the risk of infections. Local bugs and disease can be risk factors when surfing around the globe.[46]

Falling off a surfboard or colliding with others is commonly referred to as a wipeout.

Rip current warning sign

Sea life can sometimes cause injuries and even fatalities. Animals such as sharks,[47] stingrays, Weever fish, seals and jellyfish can sometimes present a danger.[48] Warmer-water surfers often do the "stingray shuffle" as they walk out through the shallows, shuffling their feet in the sand to scare away stingrays that may be resting on the bottom.[49]

Rip currents are water channels that flow away from the shore. Under the wrong circumstances these currents can endanger both experienced and inexperienced surfers. Since a rip current appears to be an area of flat water, tired or inexperienced swimmers or surfers may enter one and be carried out beyond the breaking waves. Although many rip currents are much smaller, the largest rip currents have a width of 12–15 m (40–50 ft). The flow of water moving out towards the sea in a rip will be stronger than most swimmers, making swimming back to shore difficult, however, by paddling parallel to the shore, a surfer can easily exit a rip current. Alternatively, some surfers actually ride on a rip current because it is a fast and effortless way to get out beyond the zone of breaking waves.[50]

The seabed can pose a risk for surfers. If a surfer falls while riding a wave, the wave tosses and tumbles the surfer around, often in a downwards direction. At reef breaks and beach breaks, surfers have been seriously injured and even killed, because of a violent collision with the sea bed, the water above which can sometimes be very shallow, especially at beach breaks or reef breaks during low tide. Cyclops, Western Australia, for example, is one of the biggest and thickest reef breaks in the world, with waves measuring up to 10 m (33 ft) high, but the reef below is only about 2 m (7 ft) below the surface of the water.

A January 2018 study by the University of Exeter called the "Beach Bum Survey" found surfers and bodyboarders to be three times as likely as non-surfers to harbor antibiotic-resistant E. coli and four times as likely to harbor other bacteria capable of easily becoming antibiotic resistant. The researchers attributed this to the fact that surfers swallow roughly ten times as much seawater as swimmers.[51][52]

Man wearing protective ear plugs

Surfers should use ear protection such as ear plugs to avoid surfer's ear, inflammation of the ear or other damage. Surfer's ear is where the bone near the ear canal grows after repeated exposure to cold water, making the ear canal narrower. The narrowed canal makes it harder for water to drain from the ear. This can result in pain, infection and sometimes ringing of the ear. If surfer's ear develops it does so after repeated surfing sessions. Yet, damage such as inflammation of the ear can occur after only surfing once. This can be caused by repeatedly falling off the surfboard into the water and having the cold water rush into the ears, which can exert a damaging amount of pressure. Those with sensitive ears should therefore wear ear protection, even if they are not planning to surf very often.[53]

Ear plugs designed for surfers, swimmers and other water athletes are primarily made to keep water out of the ear, thereby letting a protective pocket of air stay inside the ear canal. They can also block cold air, dirt and bacteria. Many designs are made to let sound through, and either float and/or have a leash in case the plug accidentally gets bumped out.[54][55]

SealMask watersport goggles made by AquaSphere

Surfer's eye (Pterygium (conjunctiva)) is a gradual tissue growth on the cornea of the eye which ultimately can lead to vision loss. The cause of the condition is unclear, but appears to be partly related to long term exposure to UV light, dust and wind exposure. Prevention may include wearing sunglasses and a hat if in an area with strong sunlight. Surfers and other water-sport athletes should therefore wear eye protection that blocks 100% of the UV rays from the water, as is often used by snow-sport athletes. Surf goggles often have a head strap and ventilation to avoid fogging[56][57]

Users of contact lenses should take extra care, and may consider wearing surfing goggles. Some risks of exposing contact lenses to the elements that can cause eye damage or infections are sand or organisms in the sea water getting between the eye and contact lens, or that lenses might fold.[58][59]

Surfer's myelopathy is a rare spinal cord injury causing paralysis of the lower extremities, caused by hyperextension of the back. This is due to one of the main blood vessels of the spine becoming kinked, depriving the spinal cord of oxygen. In some cases the paralysis is permanent. Although any activity where the back is arched can cause this condition (i.e. yoga, pilates, etc.), this rare phenomenon has most often been seen in those surfing for the first time. According to DPT Sergio Florian, some recommendations for preventing myelopathy is proper warm up, limiting the session length and sitting on the board while waiting for waves, rather than lying.[60]