Monofin
Encyclopedia
Swimfin
Swimfins, swim fins, fins or flippers are worn on the foot or leg and made from finlike rubber or plastic, to aid movement through the water in water sports activities such as swimming, bodyboarding, bodysurfing, kneeboarding, riverboarding, and various types of underwater diving.Scuba divers use...
typically used in finswimming
Finswimming
Finswimming is the progression of a swimmer using monofins or normal swimfins either on the water surface or underwater, using only muscle strength. It is a discipline of underwater sports. The competition distances are same as for swimming...
and free-diving
Free-diving
Freediving is any of various aquatic activities that share the practice of breath-hold underwater diving. Examples include breathhold spear fishing, freedive photography, apnea competitions and, to a degree, snorkeling...
. It consists of a single surface
Surface
In mathematics, specifically in topology, a surface is a two-dimensional topological manifold. The most familiar examples are those that arise as the boundaries of solid objects in ordinary three-dimensional Euclidean space R3 — for example, the surface of a ball...
attached to footpockets for both of the free-diver's feet.
History and production
Monofins were introduced in 1972, by a Ukrainian finswimming club, and have been used for finswimmingFinswimming
Finswimming is the progression of a swimmer using monofins or normal swimfins either on the water surface or underwater, using only muscle strength. It is a discipline of underwater sports. The competition distances are same as for swimming...
competitions since, allowing monofin swimmers to reach speeds of 12km/h.
Monofins can be made of glass fibre or carbon fibre. The diver's muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
power, swimming style, and the type of aquatic activity the monofin is used for determines the choice of size, stiffness, and materials.
Uses
To differentiate between the use of monofins and conventional fins, the latter are sometimes referred to as stereo fins or bi-fins. The monofin swimmer extends arms forward, locking hands together, locking the head between the biceps. The undulating movement starts in the shoulders, with maximum amplitude towards the hips, the legs almost don't bend to transfer the movement to the monofin. This technique is called the dolphin kick.Monofins can be used to swim:
- at the surface of water, in swimming pools or in the sea.
- under water without air (apneaApneaApnea, apnoea, or apnœa is a term for suspension of external breathing. During apnea there is no movement of the muscles of respiration and the volume of the lungs initially remains unchanged...
) - under water with air provided by a compressed air tank.
By slowly oscillating the surface of the monofin when submerged, freedivers can generate large amounts of thrust
Thrust
Thrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction the accelerated mass will cause a force of equal magnitude but opposite direction on that system....
even with small or slow movements. This preserves energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
which helps with breathholding (apnea
Apnea
Apnea, apnoea, or apnœa is a term for suspension of external breathing. During apnea there is no movement of the muscles of respiration and the volume of the lungs initially remains unchanged...
).