the Pearl
Quantum Surf Physics
Donn Ito
by
Introduction
The pearl is one of surfing’s most dangerous wipeouts. It is a violent wipeout that catapults a helpless surfer toward many dangerous hazards. In a pearl, the nose of a speeding surfboard makes a high impact collision with water. The collision of board and water usually occurs in a dive, sometimes called a pearl dive. The impact abruptly trips up the surfer and launches him through the air. The wipeout itself may not be injurious, but; it may land the surfer in very dangerous predicaments. Many dangers lurk such as drowning in a turbulent underwater hold down. A collision with shallow rocky bottoms can fracture bones and render a surfer helpless. Sharp reefs can gash and lacerate flesh. Lastly, a flying surfboard can spear a surfer or knock him unconscious. The goal of this study is to reduce wipeouts that cause injury, concussions and drownings.
A shallow pearl tips Mark Foo's balance causing a fatal fall.
Brief History of the Flatbottom
Original surfboards were wood and often made from wood boards. This made them flat and heavy. They were great for planning at a slight angle.
Note the rounded bottoms on the boards to the left.
Foam was discovered and performance vastly improved. The early longboard hotdogging era was dominated by boards with roll and belly. Roll increased maneuverability and belly reduced pearling on boards with minimal nose rocker. Nose riding became very popular and flat bottoms were initially made to maximize lift in nose riding. Flat bottoms extended time on the nose. The flat bottom expanded its domination as belly disappeared and roll was replaced by Vee in the tail.
The shortboard era followed with discovery that, the flat bottom made a natural square rail edge. This increased the versatility for single fin surfboards. The hard edge could hold a very steep wave. Performance continued to improve into a new era of multiple fins. Performance became more vertical as boards with additional rocker were more forgiving on vertical reentry. Surfers took to the air and high nose rocker with flat undersides, worked well when the nose remained out of water. When a surfer failed to keep his tip up, he paid a painful price. Surfboards got shorter and pearls were reduced. High rocker fits in a steep wave better when the board is shorter. Shorter boards work well but, the danger of the pearl still exists.
The extreme nose rocker may be distorted by the camera lens in this photo of
Mark Foo. Mark caught his nose a couple times on his last day at Mavericks.
Alternative
Shallow pearls may be saved by a change in surfboard design. A deep pearl penetrates water at an angle of attack too extreme to recover and cannot be saved. A shallow dive on a board with a modified bow shape can level off. The board can ride further and possibly resurface. The bow is the nose underside of a surfboard. It leads the ride and can clear a path for the rest of the board to follow. A shaped bow can allow the board to move “in water.” Surfboards move “in water” and “on water”. Speed is enhanced by surfboard displacement shapes when moving “in water”. Speed is hindered by displacement shapes when moving “on water”. Understanding how speed is affected by design can engineer better surfboards.
The red area is where impact with water can disrupt a rider's balance or catapult him.
Combining round and Vee shapes reduces impact mass and allows penetration into water. The board continues to move in a flat landing or pearl.
Archimedes/Displacement & Floatation/Moving “In Water”
When a surfer moves at lower speeds, his surfboard partially submerges below the waterline. Initial movement starts in the displacement phase, with paddling. The speed of a surfer paddling a waveless and windless sea, is limited to the power he produces. The surfer cannot paddle fast enough to plane at top speed without a wave to assist him. While lying prone on his surfboard, gravitational forces on his weight partially submerge his surfboard. He positions himself on the board at the center of gravity to reduce resistance. Buoyancy provides support instead of speed. The more board volume he has, the more buoyancy he gains. Buoyancy creates more uplift, with less board below the waterline. Archimedes discovered objects float by displacing a volume of water equal to its mass. The bigger the surfboard, the less the board extends underwater. This reduces the amount of water that must be pushed and allows a surfer to paddle faster. As he gains speed he enters the transitional phase.
Transitional functions such as turns, cutbacks, stalling and rapid paddling are accomplished, with a small section of the surfboard submerged “in water”. A surfer shifts his weight to turn and maneuver his surfboard. Movement “in water” is accomplished by moving water out of the way. In these phases of a ride, a surfboard moves water in order to move. Surfers displace water and methodically replace water, called displacement and discovered by Archimedes. On performance surfing, riders spend more time in the transitional phase linking turns. In large waves speed and planning are the priority.
Bernoulli/Hydrodynamic Lift/Moving “On Water”
Moving “on water” is accomplished with hydrodynamic lift, discovered by Bernoulli. Lift is created by speed on fluids, including air with flight. Water becomes somewhat impermeable to speeding objects. Initially, while paddling and transitioning, surfboards push water out of the way to move. This takes time, speed takes time away. When water cannot move and the surfer continues to accelerate, he can rise to the surface and ride “on water”. Surfers are supported “on water” with speed instead of buoyancy, the supporting force is known as lift. This is the planning phase of movement.
Galileo/Speed & Weight
Galileo experimented with falling objects and found objects of varying weights, falling from the same height, will travel at the same speed. Increasing height will increase speed. The higher the fall, the faster the fall speed until it reaches terminal velocity. Gravity accelerates a falling object, a rolling ball downhill, and a surfer dropping down a wave. A surfer is powered by gravity and wave energy. A surfer links both sources together with gliding turns and cutbacks to flow in a ride.
Weight
Weight will not increase the speed of a falling object, but; it will increase the force of impact. When falling in water, a heavier object will make a bigger splash.
This will move a little water out of the object’s path, but not enough to allow displacement. With flat landings, water blocks initial penetration. Heavier surfboards will penetrate the surface and are used in tow surfing. Weights are sometimes added to increase penetration on lighter boards. Surfers sometimes ride the forward on their boards to stabilize it through whitewater, foam balls and turbulence. Riding with weight forward adds stability but may sacrifice speed. A combination of weight and shape may reduce Pearls.
Ex. Lift abruptly stops flat falling objects “on water”. Fast moving falling objects
with mass momentarily stop, on the surface, before sinking and penetrating
deeper. Water needs time to gradually move and cushion the object. High
impact Instantaneously stops a fall. The momentary pause is not easily detected
visually, however; the collision with water can cause internal Injury or death.
Impact with water breaks Garret Mcnara's arm in multiple places.
Moving Water
High impact with water stops a surfer’s flat landing in an air drop or aerial maneuver, because water cannot immediately move. The surfer is catapulted with his speed or kinetic energy when his surfboard abruptly stops. Most surfboards have flat bottoms. On a flat bottom board, very little water is moved out of the way to allow displacement. This is the reason flat bottoms surfboards do not move well “in water”. Flat sections of the board push water forward in its path. It cannot cut through water so it plows it forward. Flat bottoms are designed to move “on water”. A flat bottom optimizes lift not speed. This is the reason most boats and ships do not have flat bottoms. The few boats that are flat need smooth calm water.
Ex. Water is more easily penetrated by a dive or pin drop entry. A flat flop
exposes more body surface area and limits penetration. When water
moves the falling body can submerge.
Flat bottom surfboards do not penetrate water deeply in a pearl. Its flat underside optimizes resistance by increasing surface mass. Water does not move, and the ride abruptly stops. Round and V bottom shapes cut through water, penetrating like a dive or pin drop fall. Water is moved aside and the surfer can continue, maybe recover by moving “in water”.
Solution/Semi-Displacement Surfboard
A good surfboard attains speed to plane on the surface and cuts through water when it slows and rides lower in water. Displacement shapes, round or Vee, cut through water and push water aside allowing a smooth transition and movement “in water “ with little loss of speed. All surfboards slow when riding “in water”, but displacement shapes continue to move through water without stopping. A flat bottom board rapidly decelerates because it pushes water instead of parting it.
A semi-displacement shape optimizes performance for riding both “in water” and “on water”. Only the nose underside or bow is vee or round. The remainder ⅔ or ¾ of the board remains flat for planning. The bow is out of water when the board planes. If it contacts water due to an irregularity in the surface or steep reentry, it pushes water aside without loss of speed. This allows it to move faster than a flat bottom, which pushes water forward in its path. This design will ride out of a shallow pearl and move through water.
Pro surfer O’Shaughnessy details his nasty Pipeline wipeout and long road to recovery (hawaiinewsnow.com)
Red O'Shaughnessy is in a shallow pearl. The nose tip is visible but the bend in the nose rocker is plowing water. His board immediately decelerates and launches him.
I hope to offer new surfboards as an alternative choice for varying conditions. The designs deviate from popular shapes that existed for over 60 years. It is difficult to initialize change. I will update this site if I am successful. Send inquiries and comments to: ito808@yahoo.com.
Volume can be reduced without loss of buoyancy due to displacement.
In Closing
The late great surfer Greg Noll built and rode boards like the one pictured below. He was obsessed with riding giant waves in the sixties, when little was known about its dangers. He successfully rides out of a pearl in the following videos. There are others which attest to the success of his design. There are also videos of wipeouts on file, because Greg pushed the limits.
A Solemn Finale
The following deadly wipeout may be prevented in the future. Kirk Passmore attempts to ride through a lump in the wave. The nose rocker bend under Kirk's surfboard pushes water and stalls. A V bottom surfboard can cut through a lump and ride "in water". Water is parted and pushed out of the way. An abrupt stop is an indication that the surfboard bottom is flat. Flat bottoms push water directly forward, blocking the path. The surfboard rapidly decelerates and prevents Kirk from escaping the looming lip. He ejects in the impact zone. The wave breaks on him, possibly breaking an ear drum. According to a witness, he did not surface and may have lost his equilibrium. The flat bottom does not move well "in water".
