Finning techniques

Finning techniques are the skills and methods used by swimmers and underwater divers to propel themselves through the water and to maneuver when wearing swimfins.

[1] This can be done to some extent by streamlining diving equipment, and by swimming along the axis of least drag, which requires correct diver trim.

[2] Good buoyancy control and trim combined with appropriate finning techniques and situational awareness can minimise the environmental impact of recreational diving.

[4] Swimfins are used to provide propulsion and maneuvering for divers, and may be designed and chosen specifically to emphasise one of these functions.

Optimisation for one generally implies degradation of capabilities in the other, and other factors such as durability and cost also influence manufacture and selection.

Finning for propulsion involves methods of producing thrust with the intention of linear motion through the water on the long axis of the body.

[6] For a given value of drag, diver effort can be minimised by using the kick stroke and fin configuration that has the most efficient conversion of muscular work into thrust.

Speed records show that monofins and dolphin kick are the most efficient, followed by long, thin and highly elastic-bladed bifins with close-fitting foot pockets.

[2][7] Dolphin kick is the technique where both legs are moved up and down together, and may be done with paired fins or a monofin, which has foot pockets for both feet attached to a single wide blade.

Monofins are used almost exclusively by competitive freedivers and finswimmers as they provide greater propulsive thrust for a given energy input, but are relatively poor for maneuvering.

The efficiency of this style is also improved by extending the arms in front of the swimmer and tucking the head down for reduced drag.

[7] Frog kick involves the simultaneous and laterally mirrored motion of both legs together, approximately parallel to the frontal plane.

[1][2] The modified frog kick arches the back and retains slightly bent knees during the power stroke, which keeps the thrust further away from the bottom when swimming above silt.

[1] Basic frog kick is a stroke with wide action, and is unsuitable for use close to a wall or in narrow spaces.

The movements are larger than those of the modified frog and flutter kicks, and the fins are more likely to contact the surroundings in a confined space.

The diver then points the fins backwards to reduce drag, puts heels together, and extends the legs to the start position.

[4] A variation uses mostly ankle action sculling for relatively fine and precise rotation on a vertical axis.

Rotation about the longitudinal horizontal axis is called rolling, and is can be performed by using opposed leg motions similar to those used for flutter kick, but with the fins spread a bit wider apart and with the fins held straighter, to concentrate thrust vertically on the power stroke, and feathered for the return stroke.

It is not often necessary to do a full backward or forward somersault underwater, but when it is necessary, it is often easier to do by coordinated arm movements, which allow a tighter rotation than finning for most people.

Changes in attitude from vertical to horizontal, and vice versa, and recovery from an inversion are more common, and involve similar techniques.

This is a fin stroke for maintaining position and attitude at the surface, particularly while waiting for a pickup or taking a compass bearing.