A springboard or diving board is used for diving

Diving

Diving is the sport of jumping or falling into water from a platform or springboard, sometimes while performing acrobatics. Diving is an internationally-recognized sport that is part of the Olympic Games. In addition, unstructured and non-competitive diving is a recreational pastime.Diving is one...

 and is a board that is itself a spring

Spring (device)

A spring is an elastic object used to store mechanical energy. Springs are usually made out of spring steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel and hardened after fabrication...

, i.e. a linear flex-spring, of the cantilever

Cantilever

A cantilever is a beam anchored at only one end. The beam carries the load to the support where it is resisted by moment and shear stress. Cantilever construction allows for overhanging structures without external bracing. Cantilevers can also be constructed with trusses or slabs.This is in...

 type.

Springboards are commonly fixed by a hinge

Hinge

A hinge is a type of bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation. Hinges may be made of flexible material or of moving components...

 at one end (so they can be flipped up when not in use), and the other end usually hangs over a swimming pool

Swimming pool

A swimming pool, swimming bath, wading pool, or simply a pool, is a container filled with water intended for swimming or water-based recreation. There are many standard sizes; the largest is the Olympic-size swimming pool...

, with a point midway between the hinge and the end resting on an adjustable fulcrum.

Springboard materials

Modern springboards are made out of a single-piece extrusion of aircraft-grade aluminum. The Maxiflex Model B, the board used in all major competitive diving events, is made out of such aluminum, and is heat treated for a yield strength of 50,000 psi. The slip-resistant surface of the board is created using an epoxy resin, finished with a laminate of flint silica and alumina in between the top coats of resin. This thermal-cured resin is aqua-colored to match the water of a clean pool.

Adjustment of the spring constant

The spring constant of a springboard is usually adjusted by way of a fulcrum that is located approximately mid way along the springboard. Springboards are usually operated in a linear regime where they approximately obey Hooke's law

Hooke's law

In mechanics, and physics, Hooke's law of elasticity is an approximation that states that the extension of a spring is in direct proportion with the load applied to it. Many materials obey this law as long as the load does not exceed the material's elastic limit. Materials for which Hooke's law...

. When loaded with a diver, the combination of the diver's approximately constant mass

Mass

Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...

, and the constant stiffness

Stiffness

Stiffness is the resistance of an elastic body to deformation by an applied force along a given degree of freedom when a set of loading points and boundary conditions are prescribed on the elastic body.-Calculations:...

 of the spring(board) result in a resonance frequency

Resonance

In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...

 that is adjustable by way of the spring constant (set by the fulcrum position). Since the resulting system is in an approximately linear regime, it may be modeled fairly accurately by a second order differential equation

Differential equation

A differential equation is a mathematical equation for an unknown function of one or several variables that relates the values of the function itself and its derivatives of various orders...

. Typically the resonance frequency can be adjusted over a range of a 2:1 or 3:1 ratio

Ratio

In mathematics, a ratio is a relationship between two numbers of the same kind , usually expressed as "a to b" or a:b, sometimes expressed arithmetically as a dimensionless quotient of the two which explicitly indicates how many times the first number contains the second In mathematics, a ratio is...

.

Counter-intuitive user-interface

The fulcrum usually travels over a range of approximately 0.75 metre (30 inches), and is set by way of a knob that is approximately 0.35 m (14 inches) in diameter

Diameter

In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...

. To stiffen the spring (as if tightening it), the knob is usually turned counter clockwise. This is counter intuitive, since usually things are tightened by turning clockwise. Additionally, if standing on the springboard, it is difficult to push the wheel with the foot, because the top of it needs to turn the other way from the way it moves. This is because the gear

Gear

A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine....

like mechanism (usually a "soft gear" made of rubber

Rubber

Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...

) is on the board and not the base, so the wheel pivots against the board when rotated. Thus users often need to bend down and set the wheel, or come down from the board to set the wheel. Thus it would be much better if the gearing were on the base so that the wheel could be pushed with the foot, but tradition (consistency from board to board) dictactes maintaining a "backwards" convention.,,

• Note - Standing behind or in front of the knob, rather than directly above it, will give you better lever
  Lever
  In physics, a lever is a rigid object that is used with an appropriate fulcrum or pivot point to either multiply the mechanical force that can be applied to another object or resistance force , or multiply the distance and speed at which the opposite end of the rigid object travels.This leverage...
  
  age to move the fulcrum. This is accomplished by holding on to the hand rails and leaning the body a few degrees, then placing your foot as low as possible on the knob. In this way, it is possible to move even the most difficult fulcrum.

Heights of springboards

Springboards are usually located either 1.0 metre or 3.0 metres above the water surface. It is very seldom that one is mounted at a height other than these two standard heights.

Historical heights of springboards

Some years ago, springboards, usually made of wood, were located at heights of either 10 feet (approximately 3m), or 20 feet (approx. 6m), above the water.

Home springboards

After an incident in Washington state

Washington State

Washington State may refer to:* Washington , often referred to as "Washington state" to differentiate it from Washington, D.C., the capital of the United States* Washington State University, a land-grant college in that state- See also :...

 in 1993, most US and other pool builders are reluctant to equip a residential swimming pool

Swimming pool

A swimming pool, swimming bath, wading pool, or simply a pool, is a container filled with water intended for swimming or water-based recreation. There are many standard sizes; the largest is the Olympic-size swimming pool...

 with a diving springboard so home diving pools are much less common these days. In the incident, 14-year-old Shawn Meneely made a "suicide dive" (his hands at his sides - so his head hit the bottom first) in a private swimming pool and was seriously injured (tetraplegic). Family lawyer Fred Zeder successfully sued the diving board manufacturer, the pool builder, and the National Spa and Pool Institute over the inappropriate depth of the pool.
The NSPI had specified a minimum depth of 7 ft 6 in (2.55m) which proved to be insufficient in the above case. The pool into which Meneelly dived was not constructed to the published standards. The standards had changed after the diving board was installed on the non-compliant pool by the homeowner. But the courts held that the pool "was close enough" to the standards to hold NSPI liable. The multi-million dollar lawsuit was eventually settled in 2001 for $6,600,000USD ($US8,000,000 after interest was added) in favor of the plaintiff. The NSPI was held to be liable, and was financially strained by the case. It filed twice for Chapter 11

Chapter 11, Title 11, United States Code

Chapter 11 is a chapter of the United States Bankruptcy Code, which permits reorganization under the bankruptcy laws of the United States. Chapter 11 bankruptcy is available to every business, whether organized as a corporation or sole proprietorship, and to individuals, although it is most...

bankruptcy protection and was successfully reorganized into a new swimming pool industry association.