a. Bodysurfing’s Rosetta Stone
b. The First Mākaha Bodysurfing Classic
c. Breeze and Gale: The Science of Wind
d. Tubes and Temporal Relativity
e. Innovation: Churchill Swim Fin Patent
a. Bodysurfing’s Rosetta Stone
b. The First Mākaha Bodysurfing Classic
c. Breeze and Gale: The Science of Wind
d. Tubes and Temporal Relativity
e. Innovation: Churchill Swim Fin Patent
Every subculture develops its own nomenclature to describe their endeavors. Skiers and snowboarders use dozens of words to articulate different snow conditions. Skateboarders have a name for every kick and flip. Likewise, waveriders have hundreds of words to describe the Ocean and waves.
Bodysurfers have developed our own words to chronicle our Ocean passion. In the United States, womp or whomp has become synonymous with bodysurfing. “I’m gonna go for a womp.” However, the origin of the word comes from early surf days when people would go for a “bodywomp” in shallow shorebreak. Womp being the sound that the body makes when splattering on the sand.
Many words are used to describe a barreling wave: tube, pit, shack, cave, keg, green room, cavern etc. We use a multitude of words to discuss conditions: glassy, blown-out, closed-out, clean, bowling, heaving, funky, crispy, lined-up, peaky, offshore, victory-at-sea, thumping etc.
We’re members of a worldwide tribe. From all corners of the globe, everywhere waves break on shore, people ride the energy. Bodysurfing is an ancient endeavor, probably the first form of recreational waveriding. It stands to reason that many cultures developed their own words for riding waves and more specifically, bodysurfing waves.
Kaha Nalu is the ancient Hawaiian word for bodysurfing. The spirit of Hawaiian bodysurfing is summarized by the Hawaiian State Bodysurfing Association’s motto: Hōpūpū i ke kaha nalu meaning “to be extremely emotionally excited about bodysurfing.”
On the Black Sea coast of Turkey, for centuries people have been partaking in a past time they call Viya, meaning waves in a Greek dialect dating back before the Ottoman Empire. Fishermen challenge themselves by bodysurfing in wintertime storm surf along the jagged Turkish coast. It is still practiced today, passed down from father to son.
In Brazil, bodysurfing is known as jacaré which translates to alligator. It has been used since the 1940’s, when bodysurfing gained popularity at Copacabana Beach in Rio de Janeiro. In the 1980’s, the term surfe de peito meaning chest surf became popular. In Peru, bodysurfing is known as “pechito” or little chest. Costa Rican’s refer to their swim fins as patas de ranas or frog legs.
Similar to a womp in the USA, Australians go for a bodybash and South Africans might run out for a quick goef. In Japan, bodysurfing is ボディーサーフィン and also known as sunori 素乗り or bare riding. Italians enjoy the Mediterranean Sea and sometimes bodysurf, called surf con il corpo. Many countries use the word bodysurf but add their own accents including: Mexico, France, Spain and Portugal.
Whatever you call it, bodysurfing is the most supreme pleasure experienced by people across the globe. If you ever find yourself on a foreign coast with waves breaking, ask around, you might be surprised to find bodysurfers enjoying waves and talking story in their native tongue.
Rodrigo Bruno in Brazil, Keali’i Punley in Hawaii, Tunc Ucyildiz in Turkey, Ricardo Añorga in Peru, Masakazu Miura Fleming in Japan, Oliver and Axel in Italy and Belly Slater in Australia
The following article was written by Hawaiian Kā’eo Awana. The photographs were captured by local photographer Philip Kitamura. Thanks to Sean Enoka and the boys for their collaboration.
Mākaha beach bared 5-6’ waves (Hawaiian scale), or 10-12ʻ faces on the day of the Mākaha Bodysurfing Classic. The waves broke from the outside point and marched into the backwash infested shorebreak. The expressions on each competitor varied from pale intimidation to ragged anticipation to anywhere in between. During check-ins, two ski’s were launched from the north end of the bay. Jet skis are a typical supplement for Mākaha lifeguards, except these weren’t lifeguard skis. To much of everyone’s excitement, the Hawaiian Water Patrol was present to ensure everyone safety. Furthermore, they would be providing assistance during heats to get competitors zoomed back out the point after catching waves. This was a pivotal moment for bodysurfing in Hawaiʻi. An average Saturday morning at Mākaha has 50+ people at the lineup with every type of surf craft under the sun. Competitors were not only able to bodysurf Mākaha at 6’ with 5 other people, but also with jet-ski assist. How can you put a price tag on this experience? With the sun peaking above the Waiʻanae mountain range, the air was buzzing with excitement.
Paipo Division- Paipo boards are typically wooden boards that take on various shapes and sizes, and have no leash. The word paipo derives from the traditional name of papa paepoʻo, which loosely translates to “board to catch waves head first.” Traditional papa paepoʻo riding looks more like bodysurfing than bodyboarding.
Mens Open Handboard – Handboard divisions required some type of handboard device. Handboard types ranged from daughter’s slippers to Kaha Nalu Bulaboards.
Handboard Final Results:
Women’s Open Handboard
Women’s Open Handboard Results:
Tandem Bodysurfing – The tandem division required two partners to be riding a wave at the same time to be judged.
Tandem Final Results:
Women’s Final Results:
Mens 50 & over
Mens 20 & under
20 and under Restults:
People who do not bodysurf often ask what the prizes are for winning a bodysurfing contest in Hawaiʻi. They expect to hear of lavish prizes, brand sponsorships, and cash that are commonly associated with the surfing industry. Most are shocked to hear that a trophy, fins, and clothing gear are typical bodysurfing contest prizes. To Hawaiʻi bodysurfers, contests serve as platform to gather bodysurfers to share the stoke of waveriding together rather than glory, fame, and riches. At these contests bodysurfers are able to reacquaint themselves with their friends, families, and meet fellow torpedo people from around the world. This is the ultimate prize of the contest; everything else is an added bonus. Contests naturally reveal winners and losers, but that is lost in the aloha that bodysurfers share with each other in Hawaiʻi bodysurfing contests. The first annual Mākaha Bodysurfing Classic was a success and raised the bar for bodysurfing contests.
Simply look at a flag and you can reckon one of the most important surf factors. If it’s pointed toward the Ocean or hanging slack, quicken your pace towards the sea. It has an enormous impact on our daily surf conditions, and in fact it is mostly responsible surf’s existence. Moving air. We call it wind. The creator and sometimes destroyer of our waves.
The Earth’s atmosphere is roughly 60 miles of gases that surround the planet. If Earth were the size of a classroom globe, the atmosphere would only amount to a couple layers of paint. Composed mostly of nitrogen and oxygen, the atmosphere is held in place by Earth’s gravity. We live and surf in the very base known as the troposphere.
Atmospheric pressure is the measure of how much air is pressing down on a given region on Earth’s surface. The movement of air from areas of high pressure to areas of low pressure is the primary cause of Earth’s surface winds. The Sun heats the Earth unevenly, so the atmosphere always contains different temperature gradients. As air molecules lose energy, they cool down, becoming more dense and sink through the atmosphere. As air molecules gain energy, they heat up, becoming less dense and rise in the atmosphere. This flow is called convection and its happening all around all the time.
Atmospheric convection creates the high and low pressure that we associate with our weather. As the warm air rises, the pressure on the surface drops. When cool air descends, the pressure on the surface increases. High pressure generally brings clear skies, light wind and stable weather. Low pressure generates precipitation, strong winds and unstable weather.
When the pressure drops, air rushes in and wind speed increases as the atmosphere attempts to find equilibrium. The rotation of the Earth causes the wind to also move in a circular pattern. Counter clockwise in the Northern and clockwise in the Southern Hemisphere: this is called the Coriolis effect.
When air moves over water, the water’s surface is disturbed. A phenomenon known as capillary waves are formed. These ripples begin the swell generating process. Gravity pulls the ripples downward but they also provide extra surface area for the wind to transfer energy into the water.
As stated before: the stronger the wind, the bigger the area (fetch) and the longer they blow- the bigger the swell. Wind speed is measured by the Beaufort Scale: from calm- breeze (4-30mph)- gale (31-63mph)- storm (64-72mph)- hurricane (72mph+). With extreme low pressure at their core, hurricanes and tornadoes contain the strongest winds on Earth, sometimes measured between 200-300mph! The planet Neptune has the strongest known winds in the solar system at 1,300mph+. Imagine the swell that would generate!
Prevailing winds are the predominant day to day winds of an area. In general, westerly winds blow across the mid-latitudes and easterly trade winds blow across the tropics. Hawaiian trade winds act like a big air conditioner for the whole island chain. Blowing from the northeast, they blow gently offshore to many famous beaches on the north coasts of the Islands. Kona winds develop from the south when the trades slow down. They often lead to muggy hot weather and volcanic fog (vog) blowing in from Kilauea on the Big Island.
Diurnal temperature variation is responsible for the daily land and sea breeze cycle that impacts many coastlines across the globe. Offshore at first light, perfectly glassy at 9am, onshore- blown out by noon and glassing off as the sun sets. The Ocean remains a more consistent temperature than the land during the day-night cycle. The gradient between land and sea temperatures decreases at night as the land cools down. Land breezes, blowing from the land to the sea, accompany many mornings with favorable surf conditions. As the sun rises and heats the land more than the water, the temp rises and pressure decreases over the land. The sea breeze picks up as air moves from the water to the land, frequently blowing out and negatively impacting surf conditions. As the sun sets, the land cools down and the evening glassoff can occur.
As coastlines vary, so too the wind’s impact on different surf spots. Nicaragua is known for all-day offshore winds because Lake Nicaragua sits just 10 miles inland and keeps the land breeze blowing most of the day. Regions with bending coastlines can be a blown out mess at one spot while around the corner is offshore. Protected coves can shelter surf spots from wind. Areas with large kelp beds are less impacted by afternoon onshores because the kelp cuts the wind and smooths the sea surface outside the lineup. Katabatic winds, meaning “downhill,” like Southern California’s Santa Ana winds can change the pattern for days at a time. When fire-free, Santa Ana, offshore winds meet swell at the coastline, SoCal waveriders rejoice.
National Center for Atmospheric Research
United Kingdom Meteorological Office
Our ancestors marked the passage of time by the moon and stars. They tracked the basic movements of the Earth in order to predict the coming changes in their environment. They developed a sense of time. Science suggests that time is a dimension. If you want to meet a friend you need to tell them a place AND time. One bit of information without the other is useless. In this way, time is a coordinate. Time seems stable and independent, but the human mind is not a nuclear clock. For beings that rely so heavily upon the stability of time, we are not particularly well suited to monitor it.
Our perception of time is even more pertinent to our day-to-day existence. We live in the present moment. It is a constantly updating sensory experience. To quote the neuroscientist and philosopher, Sam Harris, “The past is a memory, it’s a thought arising in the present. The future is merely anticipated; it is another thought arising now. What we truly have, is this moment.” We have a tendency to forget this truth. We allow ourselves to be consumed by a history that has no more power to harm us than does a future that may or may not ever arrive. We have a problem of focus.
Enter the tube, like flies to honey. We are addicted to putting our head the bowels of a heavy experience. In doing so we have unwittingly clued into a meditation, an exercise in mindfulness that clears the way for our neurons to observe reality without the calamity of a past or anticipated future. The nature of our shared pursuit lends perfectly to maintaining consciousness in the present.
Waves are perpetual, washing ashore in perfect succession. Like the march of dimensional time, they will crash to the shore to the end. We venture to meet the waves where they crash. While swimming out we may be concerned about a dropping swell or a rising tide. We could find ourselves consumed with what if’s. For many of us, the instant the wave has pitched above our brows the concerns vanish.
Our consciousness is in awe of the light waves painting the water molecules. We fight our Corneal reflex to push the visual experience to its limits. So base is our draw to see that we’ll fight our own protective instincts. Our focus has shifted to the present. This shift allows us to experience the world at its true nature. There is no room for interpreting ghosts from our past when our full and undivided attention is processing as much sensory input as we are physically able. In this way, we manipulate the very fabric of time itself.
Research suggests that our mental engagement slows down our perception of time. Not only are our memories of tube-time vivid, but they seem to last much longer than they do in objective reality. You may have felt that you were in the tube for seconds while your friend on the shoulder experienced the passage of those moments in a different way. The same could be said for the moments you experience before a car crash that you can see coming. The world slows to a crawl when we are mentally invested in our present. And, what’s more, our typical tube ride may be temporally built to perfectly maximize our experience.
British journalist Claudia Hammond in her book, Time Warped: Unlocking the Mysteries of Time Perception, reports on research suggesting “humans process the world in three second increments.” A three second barrel section could overwhelm our processing centers slowing time to its minimum velocity. Perhaps, bodysurfing is the perfect mindfulness event, bringing together our need for shortened, but rich experience. The only requirement is to go. Be there. Our history is deep with obsession over the fountain of youth because we recognize the governor on our own existence. The true challenge is bringing your “tube experience” into the rest of your reality, but that is a conversation for another day. In the meantime, get your head out of the clouds and into a tube.
In the 1940’s Owen P. Churchill designed innovations to Louis de Corlieu’s original swim fin patent. These innovations led to the efficacy and staying power of the modern rubber swim fin. Churchill’s original design is still popular today, 70 years after it’s creation. The following text and visual are from the original patent as referenced by Google Patents.
June 15, 1948. O. P. CHURCHILL 05 SWIM-FIN Original Filed Sept. 27, 1940 OWEN CHURCH/LL,
Rented June is, 1948 SWIM FIN Owen P. Churchill, Los Angeles, Calif.
Original No. 2,321,009, dated June 8, 1943. Serial No. 358,637, September 27. 1940. Application for reissue February 18, 1948, Serial No. 9,261
My invention relates to a novel type of swim fin which is attached to the feet and is used as an aid in swimming, water treading, life-saving, and in other aquatic pursuits.
My invention more particularly relates to improvements in swimming devices, which are worn on the feet of the person engaged in aquatic activities and whereby the swimming speed is materially increased. My invention, in the experience of aquatic experts, instructors and professional swimmers, represents an efficient and practical improvement in swimming means. It has been approved and is being regularly employed by professional swimming instructors, coaches, swimmers, life guards and the like.
The use of devices embodying my invention enables a person to propel his body through the water at a materially increased speed and at a minimum of effort and fatigue. The device may be used with equal advantages for either long or short distance swimming.
The feet and legs of a human being were not designed by nature for swimming and other water activities and the use of my invention converts the feet into swimming members of correct hydrodynamic structure and design.
Swimming instructors employ devices incorporating my invention as it has been found that the use thereof gives confidence to beginners, and the art of swimming may be learned much more quickly and readily than where the unaided feet are relied on.
By increasing the speed of the swimmer the devices employing my invention likewise act to elevate the feet of the swimmer and thereby tend to overcome a problem which always confronts persons who are learning to swim, as it is difficult for a beginner to keep the feet elevated.
In addition to increased speed, the use of my invention enables a person to tread water much with great efficiency by persons engaged in diving. The devices may be employed in such sports and industries as the following: spearing fish, abalone hunting, lobster catching, pearl diving, etc. They may also be used very successfully for swimming under water or for standing in and treading water when it becomes necessary to inspect and disengage mooring lines and anchor chains of vessels which have become fouled or tangled and generally to inspect the condition of a vessels hull which is at or below the water line. In such connection the devices enable the user to have the free use of his hands and arms while supporting himself in the water by means of the devices in a substantially upright position.
My invention so materially increases the speed of a swimmer that ordinarily a person using same can swim as fast without his hands as he could by employing his feet and legs without the devices. The devices also enable life guards and others who desire to wear life belts and jackets to progress with material speed through the water, which is ordinarily very difficult, if not impossible, without the use of my invention.
Devices employing my invention can be used with equal efficiency for any kind of a kick employed in speed and short or long distance swimming. They have been found advantageous for the scissors kick, the flutter kick, the frog kick, and all other well known movements of the legs and feet which are variously employed by swim more efficiently and safely and in that respect is a distinct advantage to persons employed as life guards, for it enables them to perform rescue work in a manner which is otherwise thought to be impractical if not impossible. For example, the life guard while using devices incorporating my invention can much more easily stand erect in the water with chest and shoulders above water and thereby have the complete free use of his arms and hands in performing the rescue work. He can also much more readily support and propel the other person through the water because of the increased swimming efficiency which the devices provide.
Devices embodying my invention have special utility in that they permit a relaxation or the ankles which is desirable in advanced swimming. The devices are also highly efficient for increasing speed while swimming under water.
Devices embodying my invention may be used mers. The devices enable a person to attain what may be termed a propeller push which resembles the action of a fish fin or tail. The tapering of the devices affords a fish fin streamlining which gives an increased area of push or propulsion with a minimum of water resistance.
I am familiar with and in fact am the exclusive licensee under, United States Letters Patent 2,099,973, dated November 23, 1937, granted to Louis de Corlieu, for Life saving and swimming propelling device. Without minimizing the efficacy and scope of the invention claimed in that patent, I consider my invention to be an improvement and to have many advantages thereover, some of which may be enumerated as follows:
I dispense entirely with any and all metal reinforcements. I thereby decrease the weight of the devices and attain such advantages as increased flexibility, which is desirable while walking with the devices on dry land or in ridin surf boards and the like, and also while using the devices in the water; I eliminate the necessity of utilizing the type of crepe rubber which the aforementioned patent prefers in order to give buoyancy to the devices and I am thereby, able to use other forms of rubber or synthetic rubber, which are much more desirable and which have a longer life than does crepe rubber; I overcome the inherent disadvantages of metal which will rust and break and ‘bend while in use and which tends to tear the enclosing rubber structure under. certain conditions of use. The hazard of injury to the wearer which is ever present in the use of metal is entirely eliminated in my invention. My devices are also constructed so as to fit the feet of the wearer which advantage is attained by molding and curving the foot pocket over the instep so as to afford a snug but comfortable fit or closure.v
My invention attains still other advantages which result from improved structure and form over the invention of the aforementioned patent, and otherwise, and which will become obvious from a further description thereof.
An object of my invention is to provide in swim-fin of the character described a relatively flexible-construction which when in use in the water will adapt itself to the movement of the feet and legs while swimming, treading water, and the like, and which with a minimum of water resistance will afford an increased area of propulsion.
A further object of my invention is to provide in a swim-fin of the character described a proto the feet of a swimmer in substantially horizontal position;
Figure 2 is a top plan view of a pair of the line 8-6 of Figure 4.
Propelling device which may be utilized by beginners as well as by expert swimmers, life guards and others, and which materially increases the speed while swimming and which likewise increases the buoyancy of the body while at rest or “standing in the water.
Another object of my invention is to provide in a swim-fin of the character described a symmetrical stream-lined molded rubber device which is relatively simple and inexpensive to manufacture and which can be molded and manufactured in one piece. In such respect I wish to point out that devices which embody the invention of the aforementioned Patent 2,099,973 are made in approximately 18 pieces which are cemented together and which have all of the disadvantages which are inherent in such construction. For instance, pieces may pull apart while in use and devices embodying my invention will last longer and will stand considerably greater stress and strain than the other type of devices.
A still further object of my invention is to provide in a device of the character described a hole or orifice disposed in the bottom thereof, which permits the expulsion of water and sand which may collect in the foot pocket and which at the same time provides a suction cup or grip when the devices are used by a person standing or walking, on a slippery-.surface. such as surfboards, aquaplanes and the like.
Another object of. my invention is to prgvidefin a device of the character described reinforcing beads along the to and bottom sides thereof which afford sufficient firmness but at the same Devices incorporating my invention may be, made of rubber or of synthetic rubber ‘orTother-VI rubber substitutes and compounds.
Another advantage possessed by devices embodying my invention, is that identification marks and symbols and instructions may be molded or impressed in the rubber and will not wash or wear off, as would be the case if they’ were merely stamped, etc.
In the drawing: Figure 1 is a perspective of the devices attached Figure ‘7 is a horizontal cross-section taken on the line 1-1 of Figure 4.
Figure 8 is a horizontal cross-section taken on the line 8-8 of Figure 4.
The preferred form chosen to illustrate my invention comprises a left fin I and a right fin I. An elastic heel strap 2 constitutes the heel portion of the device and joins a central portion 3 which consists of a hollow wedge shaped foot pocket 4 having a convexly curved top 5 and bottom 8. An equivalent structure and form might eliminate the convex curvatures, but I prefer them as shown to conform to the instep and ball of the foot respectively.
It would be an equivalent to use a stronger or larger heel strap than the preferred form illustrated in my present application, or even to eliminate the heel strap entirely and to extend the foot pocket to the extreme rear end of the device.
A hole or orifice l is disposed in the bottom of the central portion for drainage purposes and to provide a suction cup on fiat surfaces.
The “toe portion 8 of the device which joins the central portion is relatively fiat and of increasing breadth and in the preferred form has a curved diagonal end 9, although a straight edge could be used. There are reinforcing tapered beads Ill extending along the upper and lower sides or edges of the central and toe portions of the device and which extend substantially to the end of the said toe” portion. It is important that these beads provide a firmness to the structure sufficient to withstand collapse under water pressure but sufficient fiexibility to permit a yielding of the fin progressively toward the toe portion as the fin is moved against the water.
The use of my invention may be described as follows: The left fin is placed on the left foot of the wearer and the right fin on the right foot, by inserting the foot within the foot pocket comprising the central portion, so that the heel strap engages the foot just above the heel or at the point where the Achilles tendon is located.
Due to the flexibility of the devices it will be found that the user is able to walk with comparative ease and unless the surface be especially rough or sharp, such as from rocks or glass, no injury to the devices will result. When the user is in the water he may employ the devices in the same manner as he would use his legs and feet without the devices, and with very little practice he will be able to augment the use of the feet and legs so as to propel himself through the water with materially increased speed and ease and with a minimum of discomfort and fatigue.
Whatever be the basic movement imparted to the fins by the wearer, such movement results in a propulsion generating at the heel and carried outwardly to the toe” of the fin. The streamlining or hydrodynamic shape, embodied in a structure flexible yet firm enough to withstand collapse under water pressure, utilizes an action similar to that of a fish’s fin or tail, and imparts a thrust during both oscillating movements of the foot.
The devices may be utilized for swimming, either in the normal position or on the back, and will afford increased speed notwithstanding the type of leg kick which may be employed.
It will also be found that a person wearing the devices may stand upright in the water by treading and expose a much greater portion of his body above the surface thereof than he would be able to do without the devices even with the hands employed as a supplementary means to keep afloat.
When standing on a wet, slippery surface such as an aquaplane or surf board, it will be found that the hole in the bottom of the center section will act as a suction cup more securely to hold the fin against the wet surface thereof. The hole will also act as an outlet for sand and water which might otherwise collect and remain in the foot pocket.
If the fin is used for life saving, it will be found that the user can readily support himself in an upright position in the water and have the full and free use of his arms and hands.
Persons learning to swim will be able to use the fins with equal facility and will find that the use thereof greatly reduces the time necessary in order to become an efficient swimmer.
Other uses and applications of devices embodying my invention will be obvious to anyone utilizing same and no attempt is made herein to enumerate all of those uses and objects.
Various modifications constituting equivalents may be used in the details of the device within the scope of my invention, and my invention is not to be limited to the preferred form which I have illustrated and described in this application.
1. A swim-fin of resilient material, adapted to be mounted on the foot and embodying a hydrodynamic fin shape comprising a heel gripping section, a central section forming a pocket to receive the forepart of the foot, and a toe extension web continuing the natural wedge shape of the foot, the toe extension web having one side diverging with respect to the other toward the free end, and said end being diagonally formed whereby the outer side is longer than the inner side, the central section and the toe extension having a gradually increasing flexibility toward the said end.
2. A swim-fin of resilient material, adapted to be mounted on the foot and embodying a hydrodynamic fin shape comprising a heel gripping section, a central section forming a pocket to receive the forepart of the foot, and a toe extension web continuing the natural wedge shape of the foot, the said heel gripping section, central section and toe extending web having one side diverging with respect to the other from the heel toward the free end of the toe extension, the wedge being longer along the outer side than on the inner side, the end of the toe extension being substantially diagonal from the shorter side to the longer side, and marginal reinforcements along the said sides whereby the fin is rendered more flexible in the region of its medial longitudinal line than along its sides, tending to cup under resistance of water and displacing water with a propeller-like thrust when moved at right angles to the normal plane of said fin.
3. A swim-fin of resilient material adapted to be mounted on the foot and embodying a hydrodynamic fin shape comprising a heel gripping section, a central section forming a pocket to receive the forepart of the foot, and a toe extension web continuing the natural wedge shape of the foot, the said heel gripping section, central section and toe extension web having one side diverging with respect to the other from the heel toward the free end of the extension, the wedge being longer along the outer side than on the inner side, the end of the toe extension web being substantially diagonal from the shorter side to the longer side, and marginal reinforcements along the said sides whereby the fin is rendered more flexible in the region of its medial longitudinal lines than along its sides, tending to cup under resistance of water and displacing water with a propeller-like thrust when moved at right angles to the normal plane of said fin, said margina1 reinforcements comprising beads raised from the upper and lower surfaces of the fins whereby a directional thrust is imparted for the displacement of water longitudinally along the surfaces of the fin.
4. A swim-fin of resilient material adapted to be mounted on the foot and embodying a. hydrodynamic fin shape comprising a heel gripping section, a central section forming a pocket to receive the forepart of the foot, and a toe extension web continuing the natural wedge shape of the foot, the said heel gripping section, central section and toe extension web having one side diverging with respect to the other from the heel toward the free end of the extension, the wedge being longer along the outer side than on the inner side, the end of the toe extension web being substantially diagonal from the shorter side to the longer side, and marginal reinforcements along the said sides whereby the fin is rendered more flexible in the region of its medial longitudinal lines than along its sides, tending to cup under resistance of water and displacing water with a propeller-like thrust when moved at right angles to the normal plane of said fin, said marginal reinforcements comprising beads raised from the upper and lower surfaces of the fins whereby a directional thrust is imparted for the displacement of water longitudinally along the surfaces of the fin, and said beads terminating approximately the same distance short of the end of the toe extension web leaving the end unreinforced whereby it will tend to flex diagonally substantially parallel to the end edge thereof.
5. A swim-fin of resilient material, adapted to be mounted on the foot and embodying a hydrodynamic fin shape comprising a heel gripping section, a central section forming a pocket to receive the forepart of the foot, and a toe extension web having one side diverging with respect to the other toward the free end, the toe extension web being relatively thin throughout its medial portion, and having marginal beads relatively thick at their forward portion and tapering to merge into the planes of the web toward the end thereof, whereby the web is rendered increasingly flexible toward the end and a directional thrust is imparted for the displacement of water longitudinally along the surfaces of the fin,
OWEN P. CHURCHILL.
You can find the full text and other patents at: