Forces in Surfing


What are the Forces in surfing?


What are the forces in surfing acting upon us while we are riding a wave?

Looking at surfing principles and the forces in surfing, we need speed and power to surf critically and to surf at a high level.

Speed, power and flow are one of the major elements in the Judging Criteria for surfing competitions and thus are a vital component of performance surfing. Even for recreational surfers, the more speed, power and flow a surfer has, the better they will be surfing!

When we catch a wave, we have a number of both external as well as internal forces acting upon us while we ride the wave.

The external forces acting upon us include the wave’s power, the effect of gravity as well as forces such a wave drag, hydrodynamic drag, the force of buoyancy and both centripetal and centrifugal forces.

The internal forces are created by the surfer’s body. They are produced through the eccentric and concentric contractions of the surfer’s muscles. As the surf board is connected to the surfer, the buoyancy of the board is another force acting that can be considered an internal force

Some of these forces we can have an affect on, others we cannot. We will very briefly look at the different forces in surfing that are experienced while surfing and what can be done to affect these if a surfer can.

Wave Power – This is dependent upon a number of factors and changes continuously. Such variables that will influence and dictate wave power include prevailing conditions and swell, the swell/wave size, the type of wave, tidal conditions, the ocean floor and ocean contours for example. 

Gravity – The force of gravity affects all bodies on earth pulling each body towards the earth’s center. It helps a surfer increase speed as the surfer goes down a wave but negatively affect that surfer when going back up the wave.

Hydrodynamic drag – This is caused by an object moving through the water. Factors that affecting this drag will include the cross sectional area that the surfboard presents at right angles to the flow, the surfboards friction on the water, the turbulence at the rear of the surfboard and the speed or velocity of the surfboard.

Wave Drag – As a board moves through the water, bow waves are created causing a resistance force or wave drag, slowing the board down.

Buoyancy – The buoyancy force is the upward force of the water on the surfboard

Centripetal and Centrifugal Forces – These are the forces that work to keep the surfer in balance when they lean off their surfboard during manoeuvres. Without these forces, a surfer would fall off their board as soon as they took their center of gravity and line of gravity outside their base of support.

Muscular force – The greater the force that a surfer can apply to their board, the greater that force will then be applied to their board and thereafter the board on the water. The water reacts by pushing back against the surfboard (Newtons law – for every action there is an equal and opposite reaction). This creates speed and power, projecting the surfer through turns.

How can a surfer influence and affect these forces in surfing? 

A surfer needs to apply only the required amount of force necessary in the most effective way. A surfer needs to understand the principle of summation of forces (each body parts action and effect on total force production during a movement) and sequential muscular involvement (that body parts and muscles have to be activated in the correct sequence to have a positive affect on total force production)

By undertaking a good strength, conditioning and flexibility program the surfer will have a greater ability to make stronger more forceful muscular contractions.

A board shaper can design and shape boards that allow the water to flow more smoothly around the board.

By taking off deeper, surfing in the pocket or catching the biggest waves assists in maximising the power from the wave.

Leaning off the surfboard as much as possible during major turns (ensuring that the surfer has the speed and sufficient centrifugal/centripetal forces to remain balanced on the board).

Ensuring that equipment choice and selection meet and match the prevailing conditions for example using a higher volume board in small, softer wave conditions.

This is a very basic explanation of the complex topic of Forces in Surfing.

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