Quantum Surf Physics
Scientific Surfboard Design Study
Learning from Your Wipeout
In a fall into the water, your body pushes water aside softening the impact. When you break the surface, water parts and moves from under your body as you decelerate. Your energy is transferred to the water as it provides layers of mattress-like support. Water cushions you in a low fall, but not in a fall from a great height. The higher the fall, the greater your speed. With a fast-moving body, water cannot move out of your way fast enough. When water cannot move, it provides a block known as hydrodynamic resistance. The same force that supports your speeding surfboard on the surface, stops your speeding body.
You can hit the water by launching from a speeding surfboards, so hard; that you hurt. Pain and even injury may occur when hydrodynamic resistance momentarily blocks your entry into and through water. The speed you carry from a diving surfboard, will cause you to briefly stop on the surface. Water does not move much with impact by speeding, flat objects. Water cannot compress, therefore; your body compresses. The water feels more like the earth with high impact. You can reduce resistance by landing in a dive or pin drop fall. This will reduce chances of you skipping on the wave surface like a flat rock. Unfortunately, these measures may cause you to hit the reef.
After a hard numbing collision with water, your body decelerates by compressing against water before penetrating the surface. The collision possibly wrenched your neck and vertebrate, this will hurt later. Your tissues and organs also took a jolting blow, when the water's surface did not give in. You probably feel a bit dizzy from a numbing blow to your head. As you come to your senses, you yearn and crave air, your lungs flattened and released the little air they held. Just when things start to calm, there is a roar and a thundering explosion. The wave breaks on you with a brutal and violent force that squeezes your sinuses and eardrums. They feel like they will burst. Water twists and bends your body into unimaginable shapes. You experience the forces of hydrodynamic resistance. It is hydrodynamic forces that bend and twists you. You are propelled against water moving all directions, straining muscles and joints as well as more distortion to your flesh and organs. The violent turbulence subsides and you feel weightless as you are sucked upward, and pitched over a large powerful waterfall. You land in turbulent frothing water still craving a breath of air. After a long struggle, you find the surface and take a deep breath, You can only take one breath as the next wave is about to break on you. You dive under for another beating, your body limp with exhaustion. You are fortunate, Mark Foo was not as lucky, his story is next.
The same hydrodynamic forces that causes harm in a wipeout, can cause your surfboard to stop in a nose poke. Hydrodynamic force when applied to the bent nose of a surfboard, can push it backward. Pearling and nose pokes have been a problem for surfers since the first Polynesian rode a wave. All surfers have experienced nose pokes or pearl dives and know the feeling of being catapulted through the air, when their boards abruptly stop. Nose pokes have increased with aerial maneuvers. There is a solution for this, one which may have prevented Mark's wipeout.
RIP Mark Foo photo Bob Bobour/edit from youtube
With a Final Breath
Mark Foo loved the ocean and the surfing lifestyle, his quotes expressed his love and commitment: "Surfing and Martial Arts are really similar. If you're into it, it's a way of living, a lifestyle. You live it; you don't just do it. My life is surfing." Surfing was Mark’s life as well as his career. He produced a TV series dedicated to surfing called H3O, his acronym for heavy water. Ironically, heavy water may have attributed to his demise. Science can prove that cold water is denser, heavier and thicker than warm. A surfboard does not move through cold water as easily as warm. This difference is not significant at low speed, however; at high speed, the temperature may be a factor. Coldwater also affects the human body by restricting movement, making breathing difficult and slowing circulation. Thus cold water is more dangerous than warm Hawaiian water.
On December 23, 1994, Mark got off a flight in San Francisco, from Honolulu. He went directly to a very dangerous surfing spot known as Mavericks. The waves were beautiful, not exceptionally large, but deceptively inviting. Videos show Mark smiling as he entered the water, not knowing the dangers that lay ahead. He caught a warm-up wave and the nose underside or bow of his surfboard stuck. Mark successfully rode out of the nose poke and planned to heed its warning by changing boards. When he disappeared friends assumed he went in to change boards. Mark did not make it to the beach as the bow stuck again, this time with a harder impact. The board abruptly decelerated and launched Mark in the air, with his final breath.
Mark once said, "The life I've had has been good enough that I can die happily. Surfing's done that; surfing's given me that. So I can accept dying while I'm surfing." No one really knows how Mark drowned. There is speculation that he hit the bottom, but; it is not known when he hit. A bottom collision may have occurred after drowning or possibly led to drowning. An autopsy revealed some plaque buildup in his arteries. In warmer conditions plaque may not be a deadly issue. Blood circulation is restricted in cold temperatures by constricting veins, conserving blood for organs. When veins constrict with an interior build-up, blocked circulation may cause a loss of consciousness. Common dangers can become deadly in cold water.
Mike Parsons, a fellow big wave surfer, caught the wave immediately after Mark’s and wiped out. Mike says he bumped into another surfer while violently churning in the cold icy water. He later realized that he collided with Mark. This confirms that Mark experienced a two-wave hold down, and was likely still alive at their encounter. Mark did not surface, true to another quote that became his epithet, "If you want the ultimate thrill, you've got to be willing to pay the ultimate price." The truth is, using Mark's experience we may avoid paying the ultimate price.
Mark rode down his last wave freely, his surfboard hit cold hard water at the nose rocker bend. On shallow nose dives, the rocker bend keeps the tip up, but; a flat underside can block the board from entering the water. Pressure on the bent nose pushed the board backward and caused Mark to lose his balance. The same force can prevent a fallen surfer from penetrating water deeply, in an impact with high speed. He can actually skip on the surface until he decelerates.
Hawaii's Fallen Surfers Shape the Future, RIP
Mark Foo left us an important revelation. It was not realized until 2013 when Kirk Passmore disappeared. Kirk was surfing at Outside Alligator Rock, with its deadly reputation. This is sadly where Todd Chesser perished. Kirk likely burst an eardrum and lost equilibrium after a crushing wipeout. He was last seen kicking his legs in the air, trying to swim the wrong way, toward the bottom. Both Mark's and Kirk's last rides were recorded with similarities. Kirk’s father allowed his son’s trailer to be posted on the internet. His gesture helped realize a discovery that may save others.
Warning: The following feature may be disturbing. The surfer's wipeout ended tragically. The trailer is made available by the surfer’s father, on youtube. Take a moment to remember Kirk Passmore. In the blurry image below, a chop is visible below his board. It is producing drag and generating a plume of spray. Seconds later the surfboard stops without submerging below the water line. Kirk is catapulted and the wave breaks on him.
During the passage of time between the tragic events, surfing changed. Successful airborne maneuvers and controlled free falls became common, as surfing evolved. Surfers were very successful flying at lower speeds, in small to medium waves. Progress came with a price, airborne surfers were enduring many bad wipeouts and injuries, due to hard flat landings. Surfers were injured as they pushed their equipment to performance limits. Thus a revelation was born, flat bottom surfboards with high rocker can stop in a high-speed landing. Modern surfing has taken the flat bottom as far as it can go. Extreme nose lift combined with a flat bow, can stall a speeding surfboard and pitch its rider. Mark's wipeout is the result of a flat bottom surfboard, making a high impact on water. The flat bottom does not always recover from a flat landing, at high speed. This is especially evident and common in colder water. Many examples of wipeouts at Mavericks are featured in this article. Cold water is denser than warm and more difficult to displace at high speed, according to Chemist Barrett Stoller. An analysis and explanation follow.
In 2011, a second beloved Hawaiian surfer drowned in Maverick's cold and violent waters. Sion Milosky, a well respected big wave rider, succumbed in a two-wave hold down, after a long session at Mavericks. Sion, a loving father of two daughters once said, "My wife, my daughters, they're what I live for." Many near-drownings occur at Mavericks, but; two deaths both Hawaiians may be more than coincidental.
Again another tragedy shocked Hawaii in 2015, not in the surf but in Lake Tahoe. Hawaii student Marc Ma, went stand up paddling with a group of college friends, in the cold Lake. The group got in trouble when gusty offshore winds strengthened, sending everyone further and further from shore. All were exhausted and approached hypothermia. Marc was the most experienced paddler in the group. In the true Hawaiian spirit of Eddie Aikau, he set out to get help. Wearing only shorts he battled the chilly wind and freezing spray. Marc was a member of his college football team; he was fit and in shape. Like Eddie, he disappeared seeking help and was not found. Rescuers spotted him but had to save the group first. When they went back for him, Marc was gone. We are certain that Marc went in peace, knowing the others were safe. He gave everything he had to help his friends and could do no more. Marc spared nothing, but; cold temperature took its toll. Expending all his energy in cold conditions may have caused a collapse due to exposure and fatigue. Marc Ma was the third Hawaiian to drown in cold water, following Mark Foo and Sion Milosky. The three loses brought awareness to the importance of cold water conditioning.
Hawaiians are not acclimated to cold water. They are well experienced in dealing with long hold-downs, extreme winds, and rough water, but; these situations become life-threatening when the temperature drops.
Our autonomic nervous system diverts blood circulation from arms and legs to our organs in cold temperature exposure. Organs continue to function but, limbs needed for swimming and survival become numb and useless. Regular exposure to cold water increases endurance and acclimates surfers and swimmers to colder environments. Casimir Pulaski, a conditioning expert, explains that surviving a perilous condition is dependent on cold water conditioning.
In the following video, Johanna Nordblad swims under the ice for 50 M without a breath. She is conditioned to her environment. Conditioning aided her recovery from a bad accident. Coldwater conditioning has other benefits: increased metabolism improved circulation and fortified immune system.
Surfboard Design Study
Surfing is constantly evolving, however; recent accomplishments exceed acccomplishments of past eras. Surfers are riding waves, bigger than anything ridden in the past. Performance increased, speed increased, and aerials improved. Speed as a function of gravity increased with wave size., The higher and steeper the drop, the greater the speed a surfer can attain. Surfers are also leaving the wave and flying in the air. At lower speeds, the flat bottom surfboard performs well. Surfers complete aerials in smaller waves on flat bottom boards, moving at lower speeds. High-performance aerial surfing at high speed introduced hard landings. Surfers cannot remain on their feet in an abrupt flat landing. In big surf, a long flat surfboard with high rocker, can suddenly stop and pitch the surfer in an airdrop. A flat bottom board stops both on the surface or below due to hydrodynamic lift, explanation follows.
Pressure is exerted downward on water with speed. Speed generates hydrodynamic resistance when water cannot move out of the speeding objects way. Speed momentarily prevents water from moving both, from under and from the front of speeding objects. When water cannot move out of a speeding objects path, speed generates resistance. Hydrodynamic force may be generated laterally and vertically. Lateral force affects speed. Vertical hydrodynamic force provides lift. Both are produced by water pressure induced from speeding objects. Hydrodynamic lift does not move water upward to support objects. Hydrodynamic force is not produced by moving water, but instead by speeding objects generating pressure on water.
For an example of lateral hydrodynamic resistance, let's insert a flat paddle broadside, into water from a speeding canoe. The canoe decelerates and turns. The paddle blocks water flow. The force generated against the paddle is hydrodynamic pressure.
The faster the canoe moves, the more hydrodynamic pressure the extended paddle generates. The paddle creates drag, a steersman controls drag to guide an outrigger canoe. Movement through water produces hydrodynamic resistance by boats and ships with submerged hulls. These vessels push against water, constantly generating hydrodynamic resistance. This restricts speed and is known as Wave-making Resistance.
A paddler on a surfboard in a wave-less ocean, is restricted in speed by Wave-making Resistance. The paddler moves too slow to generate a complete hydrodynamic block, but; he generates resistance against his surfboard bow with each stroke. Over time resistance results in fatigue. The resistance limits his progress. The paddler will never get his board on a full hydrodynamic plane without a wave to add power. His top speed is restricted similar to sailboats or large ships. Movement through water is accomplished by moving water. Hydrodynamic pressure pushes against a vessel's bow when it moves. This creates a bow wave and restricts speed. The exception to this is prevalent in speed boats. Planning boats possess the ability and power to rise above Wave-making Resistance. Speed boats or planning boats ride on the surface. Resistance on the bow is eliminated when it is out of water. Upward lift supports the vessel on its aft half, only a trailing wake is produced. A surfboard gliding down a wave, planes on the surface similarly.
An example of upward lift, is the support it provides when we dive into water. As you penetrate water in a dive your body pushes water out of your path. Water pressure against your body is hydrodynamic force. Your energy is transferred to water in the form of waves. You generate waves, slowing and descending deeper until your energy or speed dissipates. Descent into liquid is only possible, if the medium has time to move out of your way.
Should you fall into water from a ledge several hundred feet high, you will hit water carrying great speed. Water cannot move out of your way in time to allow penetration. You will momentarily stop on the surface, blocked by water until you decelerate. Water cannot absorb your impact, your body must take the crushing blow. Depending on how you land, you may sustain injuries.
Water supports you briefly, on the surface with hydrodynamic resistance. Water cannot compress, due to the intermolecular bond of hydrogen atoms. There is no space for molecules to compress. Water becomes more like earth to speeding objects. In high impact with water your body compresses.
Surfboards plane with hydrodynamic lift. Water cannot move out from under a speeding surfboard and provides support. The surfboard is no longer supported by buoyancy alone. Speed keeps it from sinking or penetrating the surface deeply. Water cannot be displaced by a speeding board fast enough to allow it to submerge. Thus a surfer can stand up and ride a moving surfboard supported by resistance or lift.
Speed lifts a surfboard by creating higher pressure on the bottom that exceeds top pressure from the surfer's weight. Daniel Bernoulli, in 1738, discovered that speed directly affects pressure in fluids, to include air. He experimented with blood flow, often painfully tapping into a patients arteries to measure blood pressure. This was before blood pressure monitors were invented. Bernoulli's formula proves that pressure is proportional to velocity squared.
Nose rocker produces a flat bent underside or bow, which creates lift by resisting deep penetration of water's surface. The flat surface resists water displacement. In a dive, it attempts to stay on top by blocking water. Pressure on a bent surface pushes the board back. Much like a paddle, a negative force or braking action is generated and is visible as spray. A bow wave forms directly in a flat surfboard’s path, blocking its progress. This block may be significant in depth due to cohesion. A flat bottom may push against a formidable wall of water.
When a speeding board suddenly hits the wave bottom, the flat bottom board abruptly stops and pitches the rider. This often occurs in free falls and aerial landings. The flat bottom cannot transition, instead it blocks movement. A round or Vee bow can absorb impact an allow the board to transition gradually to a lower speed.
The photo below is of a surfboard in a shallow pearl or nose poke, the arrow indicates hydrodynamic force blocking forward movement. The nose is distorted due to light refraction. The bend in the bow is producing drag. Water over the top of the board is not a factor. It spills over the deck in an eddy. Pressure from the top is generated by the surfer's weight and speed, not water. Instead of preventing a nose poke or pearl dive, nose rocker can increase its chances.
The following trailer features Dave Wassel, veteran big wave rider. He either hits chop or the wave face, after the nose is lifted into the air by wind. A screen shot from the ride, is posted below, from Surfline.com, Dave looks positioned to make the drop. Look closer, his trailing wake is broken. There are tiny gaps in the trail, which suggests that the board left the wave, airborne. Note also the wake coming from under the front of Wassel's board. It shoots knee high spray over the board. This evidence suggests the board fell and landed flat. This generated a forward wake under the nose. We cannot see how water is moving under a surfboard. Wake and spray are clues to what water is doing. Physicists discover planets by studying irregular movement of nearby specks of light. Water spray may reveal resistance or drag. The spray also suggests that Dave's surfboard is flat. Further explanation is forthcoming.
Surfline.com surfline tv greatest wipe outs.
Shane Dorian survives a terrible wipeout after encountering chop at Mavericks.
Note spray shooting from under the nose of Shane's board. Youtube
Next feature, Shawn Dollar’s board sticks and stops on the surface. It pearls after he is launched in the air. The rocker bow or bend in the nose stops his ride. Spray shoots from under his board as it pushes water. See link to Surfline.com surfline tv greatest wipe outs.
Flat Bottom Surfboard
The flat bottom surfboard is the most successful surfboard design, in recent surfing history. It has been the standard for well over four decades. The flat bottom is used in over 90% of surfboards, and 75% of standup surfboards ridden today. The flat bottom is a planning hull, riding on the water line. This hull is combined with V’s and concaves, in the tail, to increase control and speed.
The surfer’s skill is an important factor. He must maintain his balance and adjust his weight to control the board. The surfer must do everything perfectly. All featured riders are excellent surfers. The wipe outs are due to the extreme conditions and limits of equipment. Surfers rarely blame their boards for a wipe out. They do their best on any board they ride and more often blame themselves for failure. Surfers can keep the bow out of water with their skills and control. Control is compromised at high speeds and when the board leaves the wave in the air. They can drift their fins and slide to the bottom. In a free fall drop back side, riders can absorb impact with their bodies and keep the bows from sticking. John John Florence and Andy Irons demonstrate their techniques in successfully free falling into steep waves.
Skilled surfers absorb impact with their bodies to keep the board moving in a hard landing. Weight is taken off the board as the surfer’s body slams into the face of the wave. The weight removed from the speeding board, prevents the bow from hitting hard and stopping. The board does not abruptly stop and the surfer is not launched. With skill and their backs to the wave, surfers also break their fins and free fall or side slip down a steep wave. This gives an advantage to back side surfers in extremely steep waves. This is not an easy task and requires skill as the following video demonstrates.
Setting an Edge
The flat bottom was developed during the single fin era. The edge or corner produced by the flat plane intersecting the rail, held a steeper wave. The wide point of surfboards were further forward of center. Riders planed riding further up on their boards. The single fin combined with the harder and longer edge held the board in the wave. The board would not roll or slip down a steep wave. Multiple fins on modern boards can also hold a steep wave, allowing a softer rail. The edge may be maintained from the tail to the nose, fading at the bow area. This will help keep the rail in the wave.
Next:The spray shooting from under Mason's board is a sign of resistance. The board is pushing water and stalling. Note the similarity of the spray, with other photos. Bottom Pic: The stall launches Mason.
vid 5 a Pics 1a & 1b
These wipe outs may have been deadly. The featured surfers are the best at what they do. Perhaps the end result may not be different with any other surfboard design, as conditions were very extreme and hazardous.
The next trailer features, Tyler Larronde at Jaws. His board sticks midway down the wave and disrupts his balance. He almost regains control, but the board sticks again. He loses control, the board stops, he is catapulted.
vid 5 from youtube
A shorter board is also vulnerable. The board does not need length to stop. Tow boards meet the same fate. Niccolo Porcella falls into a trough at the wave's bottom and gets stuck. Water moving rapidly up the wave face, pushes against the board's bottom. This is evident from spray shooting from under his board, see red arrow. A wake is created and blocks the board. The bottom is likely too flat. Teahupoo clip from WSL greatest wipe outs and youtube.
Rapid Streaming Water
History links our past to the present. It helps us to recognize events which advanced our lives, civilization and technology. Surfing has deep roots in Hawaiian culture. In exploring this past, we can find how those before us advanced. Our past is a compass to the future.
Many surfers today, do not know what surfboards of the past look like. Fewer have ridden one of these surfboards. The boards were big, heavy and very difficult to maneuver. Shapes were not as refined as today's. In spite of this, these old shapes can out perform today's shapes, in chop. A very good design recurring on most boards of the past, was abandoned and lost over the years. This design was used by surfboard innovator Bob Simmons possibly as far back as 1945. Simmons designed the modern surfboard. His design was known as the hydrodynamic planning hull. It was popular for many years before being replaced with the faster flat bottom.
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The next clip from You Tube, takes us back on an epic ride with the forgotten surfboard design. Note the bottom hull contours of the boards, as they are carried down the shore.
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Greg Noll successfully rode across several chops without catapulting. The board bounced, however; with his skill, the ride continued. Chops came in a series, causing the board to bounce repeatedly, but; the board kept moving. The last chop launched the board in the air. The surfboard continued moved through chop without stalling.
The next video opens at Waimea Bay with Jose Angel. In the second ride, Greg Noll recovers from a shallow pearl. This is not common today. Note the third ride, the inside surfer's hull catches. It releases and does not launch the surfer. Modern flat surfboards rarely release from high speed water impact.
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The bottoms of the surfboards were rounded. In the old days, the rounded shape was called belly. Belly deflects chop and absorbs impact. Old Polynesian canoes have a rounded bottom, which might have influenced surfboard design. There are no surviving ancient boards to ascertain a Hawaiian origin. Some of the surfboards Duke Kahanamoku rode were predecessors of this shape. Tom Blake was the likely designer. Tom is shown below, at Waikiki in 1929, note the rounded hulls on the left. Blake was a waterman, inventor and surfboard builder. He is also credited for early use of a fin. Duke rides a boat like hulled board in the video from youtube below.
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The boards of the 60s not only rode over chop without stopping, but; were capable of riding out of a shallow pearl. The next trailer again features Greg Noll. His board sticks, then resurfaces, pushing water without stopping. The ride is at the end of this clip from youtube, at the 4:05 minute point. The picture on the left is a frame from Greg's ride. Note how water is deflected by the round bottom. Spray engulfs Noll. This differs from the wake spray generated by a flat bottom which only comes from under the nose. Water is pushed aside by a round bottom. Noll's surfboard continues to move. Water moves out of the board's path, generating a plume of spray. Noll's board skims water on the wave face, where modern flat bottom boards decelerate and stop.
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Skill and determination are factors to Noll's success. He successfully rode out of many dives moving at high speed. Rarely do modern boards recover from a pearl.
Eddie Aikau riding a round bottom surfboard with little rocker, similar to the replica below, survives two nose pokes. Note the large ball of spray that engulfs Eddie. This represents the volume of water that must be displaced out of the board's path, to keep it moving. Flat bottoms generate less spray because they displace less water. Water accumulates in front of a flat bow and causes it to stall in a nose poke. Both riders are behind the peak and bailed seconds later.
Modern surfing dictates innovation. Surfers need a surfboard capable of riding through a hard impact with water. In chop and in steep clean conditions, speeding boards stop when the bow contacts water at the proper angle. The longer the surfer remains riding, the further he can progress.
Blending designs of the past, with the present can produce a design for the future. Using Physics, we can overcome forces impeding performance. Understanding physics, we can apply Marine Technology to improve surfboard design.
There has not been much deviation from the traditional flat hull surfboard design. The flat bottom is very popular today. Surfers are using this design in waves of all sizes and in all conditions. The flat bottom is used in large waves with rough or choppy conditions. Surfers are also using this board in extreme conditions. They are riding steeper, deeper and in the air on waves possessing inherent deadly consequences. Thus surfers enter a new extreme environment on the same flat bottom shape.
Today's new maneuvers and new exploration of extreme and large waves, require new designs. The landscape has changed, surfboard design can improve performance. Today, surfers are often airborne, in both small and large waves. This adds a new dimension of danger, which requires innovation. Boating designs are scientifically engineered. Surfing designs tend to be artistic. Art, by nature, can be surreal. The perception that flat bottom is the best aesthetic and functional design for all conditions, may not be true. The flat bottom is a good design, however; evolution has changed the playing field. The flat bottom may not work very well in this new environment.
The flat bottom rides on the surface and needs smooth water to perform efficiently. Chop slows all surfboards, but; chop can stop a speeding flat bottom board. At slower speeds, in smaller surf the flat bottom excels. The flat bottom adds stability and reduces tipping at slower speeds. Modern vertical surfing has taken the flat bottom to its limits. An off the lip is often accomplished by breaking fins free and falling to the bottom. Take offs under the lip are done by launching the board into an air drop. Surfer are landing these, but; sometimes without riding away.
Problem: Surfing evolved with the introduction of flight. Surfers are landing high aerials and airborne free falls. Surfboards may abruptly stop at high speed on impact with water.
At high speed, hydrodynamic resistance pushes against the flat underside at the nose rocker bend, stopping movement.
Research Subjects (follow): Physics, Wave Making Resistance, Cohesion and Adhesion, Nose Rocker, Gravity Force, Bow, Marine Technology, Movement Phases, Kinetic Energy, Hulls.
Soluion?: Semi-Displacement Hulls with moderate nose rocker can push water aside minimizing deceleration, allowing transition to planning with hydrodynamic lift.
Physics is the study of matter moving through space and time. Movement through space generates waves. Every action or motion generates waves. We constantly generate waves in our daily activities. Examples are air waves, produced when we move and sound waves generated by speaking or yelling. When a surfer rides a wave, he simultaneously creates waves as he move through water.
Physics defines a wave as an oscillation moving through a medium, which transfers energy. The surfer’s medium is water, he transfers energy to water by displacing it.
Wave Making Resistance
Everything moving through water generates waves. A splash is a wave and a wave is also called a wake. Wake production can slow and stop a surfer. A bow wave which forms under a slow moving surfboard, is water the surfer moves with his energy. Energy transferred to water must be replenished continuously, or the ride will end. The main source of energy for a surfer is gravity, which supplies kinetic energy. When a surfer does not have enough kinetic energy to displace water out of his path, the ride ends. An example of this is a pearl. In a pearl dive, the nose of the surfboard submerges under water, and the surfboard stops. A surfboards stops in a pearl for several reasons. One reason is the surfer burns up his kinetic energy and has no means to acquire more. Another reason is it creates drag in the form of a bow wave, even under water in a deep pearl dive.
Cohesion and Adhesion
Water sticks to objects, this is adhesion. Water sticks to surfboards, creating a water layer that moves with a surfboard. This water layer moves independent of surrounding molecules, creating turbulence, which is drag. A surfboard pushes water at lower speeds producing adhesive surface resistance and a bow wave.
Water sticks to itself, forming puddles, lakes, seas and oceans. This is known as cohesion. Hydrogen's inter molecular bond holds water molecules together, making water viscous and resistant. Water resistance prevents a surfer from bouncing off the bottom, in a wipe out. When a surfer falls in water, he generates many little waves which radiate from his body. The falling surfer displaces water in wavelets as he sinks. A surfboard displaces water to move. At high speed water cannot be displaced fast enough and blocking speeding fast objects. Hydrodynamic resistance or lift is created.
According to renown chemist Barrett Stoller, the inter molecular Hydrogen bond is very strong. The bond is even stronger in cold temperatures, which may affect surfboard performance. The Hydrogen bond resists parting by flat speeding objects. There is very little space between water molecules, therefore; water will not compress. It actually pushes back when objects his its surface at high speed. On the other hand, you can part water by slowly moving your finger through it.
Water Cohesion Protects Surfers
When someone falls in water, they displace water by pushing it aside. As the person sinks, water moves out of his path. Sink rate or descent speed gradually decreases to zero. Water displacement cushions the fall. Water is displaced and not really compressed. in a fall with lower impact and lower descent speed, water is displaced by the gravitational force of the person's weight.
Falls from heights above two thousand feet into water, are usually fatal. At these heights objects attain terminal velocity, which is the maximum speed reached by falling objects. Due to velocity of the object, water cannot move out the way fast enough. Very little water is displaced by fast moving, objects. This causes a very hard landing.
Water Cohesion Can Increase Paddling Speed
When a surfer strokes hard, he creates a wave, with his hand and arm. This is again Wave Making Resistance. This resistance propels him forward. If he opens his fingers, he creates a larger wave, increasing resistance. Open fingers grab more water due to cohesion. Water molecules stick together to form a larger wave. This will increase thrust and add power to his stroke. When open fingers move rapidly, their wakes overlap and form a single large wake. The finger gaps are filled by the wake. When his hand moves slowly, the fingers instead, part water individually. With a slow stroke, water slips through his fingers. Higher hand speed with fingers opened generates greater resistance. This is a technique used by many Olympic swimmers.
The Foam Ball/Water Parts Water
Waves get their form, shape and size due to water cohesion. When a wave breaks, the lip impacts the base of the wave and breaks water cohesion. This creates two wakes or splashes. One wake shoots water and spray upwards in front of the wave. Another wake shoots water into the wave or barrel. The water shot into the wave, rolls in the curl. Due to the sticky properties of water, it develops into a foamy ball. This ball is called a foam ball. The foam ball can be blown out a hollow wave, with compressed air. A blast of air shoots out of the wave, when the cavern collapses.
A surfboard has rocker or nose lift, to prevent the board from penetrating the surface and submerging. Rocker has diminishing returns, too much can slow the surfboard, and too little will cause it to go underwater. Rocker forms a bow or bend on the underside of the board. When this bend is extreme, and the bottom is flat, it is exposed to contact with irregular water surfaces. At high speeds, it is vulnerable an abrupt impact, which can launch a rider. Speed is the essential factor. At lower speeds, extreme rocker with a flat bow, displaces water and surfboards continue to move. When acceleration and deceleration is gradual a flat bottom works well, absorbing impact and displacing water. The flat bottom cannot function well at high speeds in uneven water surfaces.
A misconception of modern surfboard design is, increasing rocker prevents pearling and stopping. The assumption is, a surfboard stops in a pearl because it cannot move underwater. This is only partially true. When the nose goes under water, pressure on the top of the board comes from the surfer’s weight and gravity forces, not water. Water over the top is shadowed by the rocker and spills over in rolling eddies. Top pressure from water is not a factor, unless the board goes very deep. Surfboards stop in a poke because the flat bow pushes water. A flat bow pushes water forward, before it is directed around the board. At high speeds, water immediately accumulates ahead of the board, creating a wake that blocks movement. The board abruptly stops and the rider is catapulted. The flat board exhausts kinetic energy. A displacement shape uses kinetic energy to push water out of a surfboard's path.
When rocker is increased by designers, it increases the protruding bend in the bow. The bow pushes water out of the rider's path, so the board can move forward. The amount of water that must be displaced increases with speed. At higher speeds a flat bow pushes water forward, building a bow wave that blocks the surfboard. Water is cohesive, molecules bond together and block a speeding surfboard. Water is unlike snow which can be pushed aside by the bend in a snowboard.
Alternatively, water can be directed under the board with concaves. Concaves need to be deep enough to allow fast passage of water. The nose may not have enough depth to allow rapid water passage. A concave nose rider traps water generating lift not speed. Concaves in the tail direct water in the trailing wake and has little affect on the bow wave.
Surfing is a gravity sport similar to skate boarding, skiing and snowboarding. Surfing differs in that the mountain changes and moves. Wave motion adds movement and danger to surfing. A fast moving breaking wave affects a surfer by either giving him a boost or a terrible beating. Ideally a surfer prefers to ride within the breaking wave using gravity to propel him. Kinetic energy is generated by gravity forces on the surfer's weight. Gravity is a surfer’s primary source of energy.
Surfers must balance the forces of gravity. For this discussion gravity is simplified, not without recognizing a surfer's dedicated discipline of balancing and controlling gravity forces. The center of gravity (CG) is a theoretical point on a surfboard where it is balanced on both horizontal and vertical planes. The further forward of center a surfer moves on a board, the more it dives and gains speed. The further aft of center a surfer rides, the more it noses up and stalls. Weight left of CG produces a left turn and weight to the right generates a right turn. Bottom turns and cut backs by skilled surfers are accomplished with a combination of aft and complex horizontal weight shifts. A surfer's timing and rhythm keep him in sync with the wave. Modern surfing with aerials, include turns in the air. Surfer accomplish all by balancing the forces of gravity.
A nose poke occurs when the front end of the surfboard sticks in the surface of the wave. The surfboard is usually nose down, relative to the center of gravity, and diving. Gravity forces on the surfer’s weight drive the surfboard downward nose first. Speed and weight are factors which drive a board in a nose poke.
When the board stops in a nose poke, it is due to resistance or friction under the board. A long held belief, is that water slows the submerged board and causes it to stop. This is only part of the explanation. Deceleration is caused by a bow wave. The bow wave is created by nose rocker bow driven by gravity forces on the surfer.
Below, a bow wave sprays water over the nose of the board and against Kanoa's forward leg. Water shooting over the top of the board does not create drag. Water shoots over the board in an eddy, even when the board goes under water. Downward force is generated by the surfer's weight, not water.
Three vectors in the photo above depict the gravitational forces at work. The vectors depict a typical inclined plane, physics analysis. The left vector is perpendicular to the board, known as the normal vector. The right is perpendicular to the horizon, and bottom vector is parallel to the surfboard plane. The right vector is the weight vector, its force increases with steepness. The force in the bottom parallel vector represents net force or acceleration. This value equates to motion when resistance or friction is low. In this ride, the bow is efficiently moving water around board, reducing resistance.
Gravitational forces can be calculated with geometry and trigonometry. Weight and mass are a function of gravitational force. It is not necessary to do the calculation in this case. The surfer's weight is a factor driving gravitational force in a nose poke. The gravitational force creates the bow wave which causes deceleration, by resistance and friction. The belief that water over a submerged nose causes drag in a nose poke, is a misconception. Water over the top effects only a very deep pearl. The misconception resulted in higher and higher nose rocker, which creates more bow resistance or friction.
The flat bottom surfboard combined with its nose rocker forms a bow under the nose. This is similar to the bow of a flat bottom boat. The bow of a surfboard, is usually out of the water when it is planning. When a surfboard hits chop or the face of a steep wave, it contacts water with its bow. The bow leads the board and pushes water out of its way. This is the surface where a bow wave is created. The bow wave is usually not visible, because it is produced under the surfboard. This is also the area where the surfboard pushes water when a surfer is paddling.
The following pictures are of an automobile wind tunnel test. The angle of the stream would be equal to a surfboard's encounter with light chop. In larger chop, the stream would approach from a higher angle. Note the disruption in the air flow. The change in flow is similar to the gap created when the air stream is deflected off the car windshield and roof. Ideally. the laminar smoke flow should remain attached to the object. All flat bottom surfboards would have a similar result.
Pic 14 Pic 14a
In boat design, the flat bottom boat is best suited for flat or smooth conditions. The flat bottom planes on the surface, performing at an optimum in flat water. In choppy and rough conditions the flat bottom boat, bounces and produces an unstable ride. A flat bottom boat can operate only at very slow speeds in rough conditions. The flatness impacts chop, while Round or V-Hulls penetrates chop. The flat bottom sustains more pounding and slamming than other bottoms. A Vee or Round Hull, is preferred for rough and choppy water, disbursing a bump rather than colliding into it.
Flat bottom boats efficiently minimize energy consumption. In calm water, they ride on the surface. The Flat bottom however, also attempts to ride on the surface in choppy conditions. When moving against heavy seas, the flat hull can lose forward momentum. This makes ocean crossing very difficult. To keep moving more energy or power is needed. More time is consumed in completing a journey. The flat bottom boat is not efficient in rough water. This is ancient knowledge. The Polynesians, Vikings and Columbus crossed oceans in round or Vee hulled vessels. They did not use flat hulls for ocean crossings.
Vid 10 features basic boat hull designs. It demonstrates how hulls function in different conditions.
The following video demonstrates the cause of deceleration for water vessels. As the boat moves against simulated waves, it slows. When it bucks against a powerful wave it almost stops. Surfboards don't often ride against large waves. They do encounter chop and the wave bottom or trough. This can cause deceleration. A boat continues to move with its power source. A flat bottom boat , would makes less progress.
A flat bow pushes a wake directly ahead of a vessel. A round or Vee bow parts water and pushes it out of the vessel's path.
The boating principle of flat bottom for smooth conditions may apply to surfboards. In good clean conditions, the flat bottom performs well. Similar to a boat, a flat bottom surfboard is also designed to ride on the surface. The flat bottom surfboard encounters resistance when a body of water, such as chop or a ledge, enters its path. In choppy, rough, and extreme conditions, the flat bottom may cause a surfboard to stop.
The Bow Wave
As any marine vessel moves, it pushes water. Energy is transferred to water by the vessel. Water builds in successive waves one on top of the other, ahead of the vessel. This generates a wave in front of the bow, called a bow wave. This wave is pushed aside and around the vessel. All vessels create waves as they push against water's resistance. As bow waves are created, resistance is over come. Energy or power keeps a vessel moving as it parts water. This energy is transferred and continues as a trailing wake. The entire cycle is wave making resistance. Boats create both a bow and a stern wave. Note the dual wake in pic 16.
PIC 15 PIC 16
A speed boat planes at optimum speed with most of its bow above the water. These hulls only initially push a bow wave. Vessels with planning bottoms lose their bow wave when they attain planning speed. The bow lifts out of the water hydro dynamically. This reduces the drag associated with a bow wave. Similarly a flat bottom windsurfer planes in the same way. The windsurfer, like a motorized boat, can overcome resistance with additional thrust from its sail. The windsurfer planes with its bow out of the water. Surfboards plane identically, usually producing a stern or rear wake. No forward wake is generated when its bow is out of the water. The surfboard differs in that it cannot generate additional energy or thrust. It has to use the Kinetic Energy it carries.
Hydrodynamic lift is the force that supports a planning water ski, wake board, or surfboard. Neither a ski nor wake board will support the weight of a rider when it is floating still in water. It is difficult to stand up on either one when it is not moving. As the ski or wake board is propelled, it is lifted hydro dynamically on the water by speed. It becomes stable when fully planning.
The surfboard planes in the same manner. It does not have a power source unless it is towed, instead surfers use kinetic energy. A surfboard hydro dynamically planes on its aft half, producing a rear wake. A flat aft tail section acts like a planning pad. The forward half of the surfboard is free of water contact, but; vulnerable to impact with the wave or chop. Lift is generated by speed on a flat surfaces. When the bow lifts out of water the bow wave dissipates. Speed is optimized when the bow no longer pushes water.
On a flat bottom, the bow directly pushes up the bow wave, ahead of the board. The bow wave formed would be similar to the wave produced on initial take off, pictured below. Peter Mel is just getting into the wave and is not yet at otimum planning speed.
frame from vid 10 vid 12
A flat bottom surfboard is similar to a table top. Both need a flat water conditions to move effectively. In the photo below a bow wave is produced under the table top. Although not visible the bow wave spans the width of the table. The bow wave is small due flat water conditions and minimal water displacement of a flat bottom. The table planes on the surface.
Water vessels go through three phases of movement. The order may vary and repeat as a ride progresses. Three basic phases follow as applied to surfboards:
1. Displacement mode, the initial phase when a board starts moving.
At low speeds, a surfboard will displace water regardless of hull
shape and bow design. The board is pushing water and producing a
bow wave. In this mode the board is moving between two waves,
the bow wave and the stern wave. The bow wave dissipates as the
board transitions and nose lifts. The displacement mode is not to be confused with a displacement hull shape.
2. Transition mode, the board starts to accelerate with a slight nose up
attitude. It is not at optimum speed. The bow wave starts to
disappear. The board is pushing less water.
3. Planning mode, the board is moving at optimum speed. The bow is
out of the water. The bow wave is gone. only a trailing wake follows. The
board is not longer pushing water. It is planning on the water surface.
During bottom turns and cutbacks, a surfboard goes through a transition phase. In a reentry or aerial landing, it is back in a displacement phase. The surfboard is constantly going through phases. The best surfboard design is one that progresses through the phases fluidly. The board over comes each episode of resistance. This is in the given conditions and with the surfers' design preference. Most surfboards will work in perfect conditions, not many will perform in large choppy or challenging conditions.
More information on trim modes is available in this link.
At the start of a ride a surfer generates a forward wave called a bow wave; and an aft wave known as a trailing wake. . As a surfer picks up speed, the bow wave dissipates and only a trailing wake follows. With hydro dynamic lift, a surfboard planes on its stern or rear end. The bow and nose are out of water, and the bow wave disappears. In the next video, note the bow wave that precedes a beautiful ride by Brett Barley, video from YouTube.
Modern surfing has disrupted the sequencing of movement modes. Movement does not progress from displacement to transition to planning. Surfers are transitioning in the air. In aerial maneuvers and air drops, they move from planning to displacement mode. The flat bottom board does not perform efficiently, in this reverse sequence. It is designed to plane on the surface. Flat bottoms can only displace water at lower speeds. It requires gradual transition to high speed planning. It is efficient in clean conditions. A flat bow must clear chop, pockets, wakes and the wave bottom. When flat bottom impacts water at high speeds, it cannot move water fast enough.
The bow leads the board and paves the way through obstacles in the wave. Chop, pockets or the wave bottom only initially inhibit performance. Water moves up a large hollow wave at high speeds, while a surfboard moves downward. When a flat surface contacts rapid streaming water, it has a damming effect. The bow tries to hold back the water flow. It immediately creates resistance and stops the speeding board.
Moving at high speeds, and nearly airborne, surfers land on varying sections of their surfboards with high impact. They land on their nose, tail, and midsections. Tail landings on smaller boards are successful in aerial maneuvers. In larger waves, on bigger boards, the success rates is not as high. The tail will penetrate water much like the nose. This is due to the rider’s weight and lower board volume at each end. A flat bow cannot penetrate water a high speed and causes deceleration. In smaller waves surfers land on the nose of their boards, then use their weight to sink and spin the board around. Two examples of tail landings follow. From Surfline.com surflinetv greatest wipe outs
vid 14 & 115
Cold water maybe the difference in the first vid, The
second is in warmer Maui waters.
In this normal progression, a board moves seamlessly The bow pushes water out of the boards path, in the form of a bow wave. The rest of the board follows until it begins to plane. Then the bow lifts out of the water. Most bows are flat, at lower speeds the flat bow moves well. At high speeds more water must be moved or displaced, especially if a boards gets airborne. The bow becomes a landing pad, due to the angle of descent and gravity. In a late takeoff with an airborne drop, a bow wave can stop movement. A flat bow with high rocker may not move enough water out of the way, fast enough to allow movement. A speeding board can get stuck behind its own wake. Due to cohesion this wake can extend very deep. The board is pushes against hydrodynamic force and stalls in the displacement mode. A Vee or round bow cushions the landing and allows the board to transition, possibly even planning again.
. Energy cannot be destroyed. It is transferred from board to water.
. Through movement an object has Kinetic energy.
. Kinetic energy can pass or do work on anything it hits.
. It takes equal kinetic energy stop an object that is moving. An object stops when: K=K
. Kinetic energy = 1/2mv
A surfer gliding down a wave has energy similar to a skateboarder, rolling down a hill. Both riders with kinetic energy continue moving through the air when their boards stop. Both use gravity as opposed to a motor and have no additional thrust available. Both have kinetic energy, due to movement, which is a function of mass and velocity.
K= Kinetic Energy m=mass, v= speed mass = bullet weight and volume
The measure of speed and mass is difficult, especially for water. Without working the equation, the value of K increases when both Mass and Velocity increase. The higher the value of K the greater the impact a surfboard will have on water. This correlates to the amount of resistance or drag it creates. More specifically the resistance wave or bow wave that it generates. In much simpler terms, the size of the splash a surfboard generates when it hits water.
There are many surfboard hull shapes; most can be classified into three categories. Each category has conditions which optimize performance.
The first is the Planning Category. Surfboards which are designed to ride on the water surface are planning boards. These are generally flat bottom with or without concaves and channels for added lift. The flat bottom generates hydrodynamic lift with speed. This board works well in smooth conditions, planning on its tail. The flat bottom also performs as a wing, supporting a rider in flight. The flat bottom is not the best for high impact flat landings. The Bob Simmons' Hydro Dyamic Planning Hull was an early example.
The second hull category is Displacement. The bottoms are usually round or vee, thus: the board rides lower in the water. At top speed it planes a little slower than a planning hull. It can be more controllable, in chop and free falls, absorbing impact. Where flat bottoms stall in flat landings, this bottom keeps moving. In high winds this hull spills air and generates less lift, penetrating where a flat bottom gets pushed or held back. The following picture is of a Displacement Hull.
Both Round and V Bottom surfboards have origins in the past. Bob Simmons introduced round bottoms in the 40's. The old Simmons hydrodynamic planning hull had a higher rail line from nose to tail. The rails were called 50/50, because the top and bottom met in the middle of the rail. The board had belly throughout most of the hull. Some boards ridden by Greg Noll had a displacement shape or roundness to the tail.
There are advantages to this design. V BottomTails or Round Bottom Tails cannot displace water ahead of the board, however; there are situations when water must be displaced from the middle of the board. It is also possible that the slightly lower speeds of these bottoms, may also help control rapid deceleration in chop. The disadvantage is rail does not hold a steep wave well and tends to roll and slip.
The final hull category is Semi Displacement. Combining the front half of a Displacement board with the aft half of a planning board produces a hybrid, Semi-Displacement board. The bow is usually rounded, Vee'd or both. The aft half underside is usually flat or slightly concaved. This board displaces water on impact, pushing it aside out of its path. Absorbing impact, it can transition and recover to get back on a plane. It planes on its aft section like a planning hull. It is as fast as a planning hull at top speed and will not stall in chop or in flat landings. The forward underside spills air and and allows wind penetration and wave entry on take off. The flat underside section of the board can still act as a wing in aerial maneuvers. Pictures of Semi-Displacement Hulls follow.
A round bottom bow displaces water and absorbs impact. It prevents the board from stopping. A V-Bottom bow will also yield a similar performance, with less loss of speed. A deep V, can cut through chop and hold the wave better. On the down side the V may penetrate and bow may submerge deeper into the water. This may be controlled by shaping the Vee to transition to a flat section, or shaping steps into the bow. These are called chines. Chines are used on many boats. They give a hull lift and may keep a surfboard from pearling deeply.
Limited editions of V noses were shaped for bigger waves starting in the 70's. In the 80's Maurice Cole and Tom Curren developed the reverse V surfboard, with V under the forward foot and flatness in the tail. This design was very far ahead of its time. They claimed the board cut through water like butter.
When chops are large, more displacement may be required, meaning more hull depth. The depth of a surfboard's displacement ability is limited to the thickness of the surfboard. The surfboard nose being very thin, limits the amount of water it can displace. It may not be able to displace enough water to keep the board moving. A surfboard with a thick nose may have more displacement potential but limits performance.
Flat bottom surfboards being planning hulls, are misconceived as the fastest bottoms. All surfboards plane with their bows out of the water. If the bow enters the water, at planning speed, the board slows. This is true for all boards. Flat bottoms slow as they enter the displacement mode. A displacement shape or semi displacement shape transitions and keeps moving.
On a steep wave, water is moving up its face. The steeper and hollower the wave the faster water moves. If a speeding flat bow enters this counter flow, it rapidly decelerates and may stop. The flat bottom blocks and pushes water directly ahead in its path. The flat surface is creating lift, which can push the board backward. A displacement shape, round or vee bow, can avoid this predicament. The shape diverts water out of board's path. In the photo below the red lines indicate fast moving water.
Link to surfline.com
Water moves rapidly up the wave pushing against the flat bottom board.
A flat bottom generates lift that pushes the board backward.
Solution: Semi Displacement Hull with Moderate Nose Rocker
The solution to prevent surfboards from abruptly stopping at high speed is less rocker, a round or Vee bow and a planning aft section. A semi displacement hull is the better design. It combines a planning aft hull with a displacement bow. Surfing evolution is directing designs toward semi-displacement hulls from the past. A Vee or round bow will push water out of the surfboards path at high speed. The surfer can progress further. This is a good design for modern big wave boards. It planes on the water surface and displaces water with its bow. Modern boards often land on their bows in a free fall. This design cushions impact, so the rider can transition to regain speed and control.
Stand up Paddleboards
The explosion of stand up paddling, worldwide, has brought new hull designs for various conditions. The displacement hull was introduced to stand up paddlers for use in choppy conditions. This design is borrowed from canoes, kayaks, boats and paddle boards. The displacement hull is not usually ridden in large surf. The bulky nose design is similar to a submarine. This may cause the hull to submerge like one on a large wave. The design efficiently glides through chop. Some features of this board may be incorporated in surfboard designs of the future.
More information about paddleboard hulls is available on the next link Paddlespecialists.com:
It is important for Surfing to sustain a link with Science. With Physics surfers can anticipate the movement of storms and the formation of waves. Physics can predict local wind conditions, which affects the quality of our surf. Tide charts are derived from the movement of the earth and moon using Physics.
Global warming is raising the level of our oceans. Our coastal areas and surf spots may disappear. Physics can track global warming. Physics can improve surfing equipment. Surfers need to be connected to the sciences and the environment. Physics and technology can improve their surfing, the future of surfing and the future of our precious earth. We can all make a difference.
Wanted: Sponsor with test team to fund research and development. Inquires:
I started shaping surfboards with old friend Tony Anjo in 1968. I took up windsurfing in the 80's and built windsurfers through the 90's. I was greatly inspired by Harold "Iggy" Ige. Harold was an innovator. My latest influence is Glen Miyasaki, who revived round bottoms. I am shaping less and researching (surfing) more.
I was drawn to Waimea Bay by its beauty, spiritual power and waves. I became a line up regular, when I was younger. I was never an expert surfer, but; I will always love surfing. Surfing has taught me many meaningful lessons, I continue to learn.
Vid 8 Vid 8a
Il 4 & 5
Pic 1a & 1b
Pic 5, 6, 7 , 8
Pic 7a frame
Pic 9 Ito Surfboards
Pic 10 /xj/th?id=OIP.M5c33bf7561aad2d0907f34b8ed9f907ao0&pid=15.1&P=0&w=300&h=300
Pic 15, 16
Pic 27 Ito surfboards