Eminent Danger

Wipeouts

A wipeout caused by Pearling or Nose Poking is a great danger to surfers. In a poke or pearl, a speeding surfboard, abruptly impacts water, often at the wave bottom. The surfboard suddenly stops moving, upon hitting water. The rider is upended or catapulted through the air. An understanding of how this happens, may reduce these wipeouts.

Pokes and Pearling

Shallow Surface Poke may be recoverable with a change in surfboard shapes. In a shallow poke the surfboard lands on the nose rocker underside, known as the bow in a boat.

Submerged Dive where the nose of the surfboard is driven deep under water. The surfboard enters water on its nose tip, diving deep. This wipeout is terminal or not recoverable on any surfboard.

Recoverable refers to extending the ride. Hypothetically, the surfer may have progressed further with a different board design. Many other factors determine successful finish.

Displacement

Archimedes, a third century B.C. Greek Mathematician, discovered that a body will displace a volume of water equal to itself to float. Buoyancy or the upward force, is equal in weight to the water it displaces.

Move Water

When a body moves in water, it takes the place of or displaces water from the space it formally occupied. Therefore, in order to move in water, a body must move water equal to its mass. The principle applies to vessels such as ships and schooners whose hulls extend deep below the visible water line.

Restriction.

Vessels are speed restricted because they are always pushing water in the form of a bow wave. They cannot move fast enough to pass the bow wave, which their submerged hulls create.

Water

Water is cohesive, it sticks to itself.

Hydrogen atoms in water bond to each other. Two separate cups of water will bond together, cohesively, when combined in a bowl. This bond may easily be parted by moving your hand through it.

Alternatively, this bond cannot be broken by speeding objects. It is difficult to run your hand through water from a speeding boat. A fast-moving hand is rejected by water with a force known as hydrodynamic resistance. Hydrodynamic resistance is generated by speed. Water's cohesive bond is Impermeable by speeding objects with flat surfaces.

Speed

Hydrodynamic resistance can both support and block speeding objects or vessels. The angle of attack and surface conditions determine if force is positive or negative. Downward vector produces head on resistance, as in a fall or nose poke. Forward thrust, parallel to water, generates lift and supports vessels on the surface. Once vessels attain planning speed, they do not have to push water out of their path to move. They no longer create a forward wake and plane hydrodynamically.

Displacement is superseded by hydrodynamic lift. Bernoulli's principle takes over Archimedes' principle. Water supports speeding vessels as long as thrust is maintained by a power source.

A fall into water is cushioned by Hydrodynamic Resistance. With speed, water becomes unmovable and momentarily blocks objects on the surface. Should you fall from a great height, you will impact water with speed. Speed increases with height, to a point of terminal velocity. This increases gravity force causing a very high impact. Water needs time to move and can't. A high impact will abruptly stop a fall on the surface. Water will be earthlike. Your body will absorb the impact, before it decelerates and submerges deeper. Falls from heights over 200 feet may cause serious injury. Landing flat with your body open and outstretched, further resists penetration and increases risk of injury and death. A pin drop landing penetrates water deeper and safer with depth. Ex. Kurt Carlsmith

Time

It takes time to move water. Penetration into liquid is only possible, if water has time to move out of the way. Speed prevents water from displacing. When water cannot move, with enough speed and planning surface, a vessel can ride on water instead of in it.

This is known as hydrodynamic lift.

Power Source

The more mass an object has below the water line, the more force required to move it. In addition, more time is required to push water. Some vessels have large hulls extending deep underwater. Moving water takes time and requires power to build speed. Speed is restricted by power source and the size of mass moving through water. Gravity and wave energy are surfing's power source. When a surfboard suddenly stops, the ride usually ends, as kinetic energy is depleted. A surfer paddling his surfboard on a waveless and windless sea is restricted to his inner strength.

Flat Surfaces

The flat bottom surfboard has been the top performing design for decades, it optimizes lift. The design performs flawlessly, if the underside bend in nose rocker does not make high impact with water. Increasing nose rocker, increases flat surface area exposed to impact.

Aerial Landings

Increasing vertical surfing brought more successful free fall landings. Surfboards stop in nose first free falls, pearl dives or nose pokes. All stops are due to hydrodynamic pressure on a surfboard's flat underside, and nose rocker bend. The bottom nose rocker bend is called a bow in boats and is where a bow wave is generated. The bow can catch the wave face, wave bottom or chop at high speed. The bow clears a path for the rest of the vessel to follow. A flat bottom pushes water forward. A Veed or round bow pushes water aside.

Pro surfer O’Shaughnessy details his nasty Pipeline wipeout and long road to recovery (hawaiinewsnow.com )

Moving in Water and on Water

A flat underside pushes water forward in its path, requiring more time for water to flow aside. Pushed water is a wake or bow wave that blocks the surfboard instantly, stopping it abruptly. The surfer is catapulted and hits water very hard, his speed prevents him from initially submerging. His body will momentarily stop on the surface with hydrodynamic force.

https://youtu.be/FEsS0T9aYUc

High rocker may initially prevent a pearl dive, but; the bow becomes vulnerable to high impact. In an air drop, the bow acts as a landing pad due to angle of attack and gravitational pull. The surfboard bow impacts the wave at high speed and launches Torrey Meister.

This is where old surfboard designs may improve surfing by extending a ride and possibly recovering from a Surface Poke. Ol designs allow a surfboard to move in water, by displacing it.

Floatation and Displacement

Research led me to experiment with some vintage designs. I discovered validity in abandoned old designs. Old surfboard shapes with bottom belly and dug out step decks, can augment modern designs. Belly can reduce wipeouts initiated by nose pokes or pearling, while step decks can improve floatation lost by reduced board lengths.

The rounded underside of will displace more water than a flat bottom, generating more upward buoyancy force. Therefore, the top may be dug out in the form of a step deck and not reduce buoyancy.

Nose Rocker and Flat Bottoms

Flat bottoms maximize planning surface and optimizes hydrodynamic resistance or lift. It is excellent for forward trimming and nose riding. As rocker increases, the surfboard starts to push water lower speeds. In a high speed impact with water, such as a pearl, flat surfaces cannot displace water. This causes catapulting or wipeouts.

The two drawings below are identical. the bottom is turned upside down. The top sketch are cross sections of a flat bottom surfboard, the second, a displacement bottom. The displacement bottom sits lower in the water displacing more water. This increase buoyancy or uplift.

My experiments have produced best results with a displacement nose entry, while retaining a flat bottom on the rest of the board. Adding a veed spine to the vintage round bottom parted water and absorbed high impact. This displacement nose is out of water during turns and planning. A hard aft rail edged can be maintained to hold the board in the wave.

Archimedes, a third century B.C. Greek Mathematician, discovered that a body will displace a volume of water equal to itself to float. Buoyancy or the upward force, is equal in weight to the water it displaces. When a body moves in water, it takes the place of or displaces water from the space it formally occupied. Therefore, in order to move in water, a body must move water equal to its mass. The principle applies to vessels such as ships and schooners whose hulls extend deep below the visible water line. These vessels are speed restricted because they are always pushing water in the form of a bow wave. They cannot move fast enough to pass the bow wave, which their submerged hulls create.

This is in contrast to speed boats which sit higher on the surface and can accelerate faster than water can move. Water needs time to move, and speed does not allow fluid enough time to move out of the vessel's path. Water resists penetration by speeding bodies and provides support or lift to speeds boats. These boats ride on the surface and create a trailing wake but no bow wave once planning. Their speed is not restricted. Surfboards plane in this manner with speed providing hydrodynamic support. Surfers are supported by their speed on water. Water takes on an impermeable characteristic with speed.

Surfers are not supported by buoyancy alone when accelerating. Speed increases pressure on water. As a surfboard accelerates its pressure on water increases. When water does not have time to move, it becomes somewhat stationary. The upthrust force of water increases to a point where it will support a surfer on a smaller and smaller surfboard. This is hydrodynamic lift or Bernoulli's Principle.

Gradual acceleration allows transition to hydrodynamic lift.

A surfer paddling in a waveless and windless ocean lull, is limited to the maximum speed he can generate with his arms. His surfboard is partially submerged, he positions himself on the surfboard to minimize water pushing against his nose rocker. His surfboard parts water with each stroke, generating a forward wake. He sprints for a wave and takes off with lift, as his speed is no longer limited. The surfboard nose rocker is out of water and no longer produces a forward wake. When water does not move it can momentarily stop movement.

Weight Equipment Rider Effects Gravity Force

Need to balance rocker with weight.

Factors which reduce pokes and pearls

Length: shorter boards

Rocker: Medium

Weight: Balance between rider nose rocker