THE TWO THINGS THAT DO MORE THAN ANYTHING ELSE to make a diver comfortable and at home in the water are good finning technique and proper neutral buoyancy, but which to cover first?
Good buoyancy control is almost a prerequisite for effective finning, especially for some of the more advanced fin kicks. But most divers learn finning first and master buoyancy later, so here we review basic finning technique and, for those who have mastered it, a selection of more advanced techniques.
While practising, always think about neutral buoyancy. |
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The standard style that everyone learns during their basic training is the simple up-down flutter kick. The legs move up and down in opposing directions, with the forward thrust being provided by the downward stroke of each fin.
Water is pushed off the upper surface of the fin and the tips bend back relative to the diver's feet. The upward stroke just slips through the water to get the fin ready for the next downward stroke.
The legs are kept more or less straight, though it is OK to bend the knees a little. The important measure is that your heels stay a roughly constant distance from your backside.
If the heels move in and out from the backside, the fins will be slicing the water in an ineffective bicycling movement rather than pushing the water backwards to provide forward thrust.
The flutter kick works best with long, gentle strokes, using the muscles at the front of the thighs to do most of the work. Long strokes maximise the time each fin spends pushing the diver forwards, and minimise the time each fin spends ineffective at the end of each stroke.
In a confined space, the strokes can be shortened to the point at which the fin-tips are just twitching, although most divers would move to a short frog-kick under such circumstances.
The big disadvantage of the flutter kick is that the wash from the fins flows down (and also upwards to some extent) at the end of each stroke. This means that it can easily disturb nearby seabed or marine life.
It is also very easy for the fin-tips to kick marine life below the diver.
However, the flutter kick is easy to use, works with all types of fin, and provides a good forward thrust that is fairly even throughout the fin cycle.
- On the surface
- During descent and ascent
- Off a wall
- When well clear of the seabed
- When swimming into a current
- When speed is required over a period of time
- Close to a silty or sandy seabed
- Inside a wreck
- In a cave
- When swimming close above coral or other delicate marine life
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The frog kick is the underwater equivalent of the breast-stroke kick.
From picture (1), the fins slip through the water out and sideways through (2) and (3) until the legs are fully extended to either side.
Forward thrust is then provided by twisting the fins, so that moving them back in pushes water back with the underside of the fins. This movement is shown in pictures (4) and (5), with completion of the stroke ready to start again at (6).
Unlike the flutter kick, forward thrust is provided only through the second half of the stroke, the first half merely positioning the fins for the thrusting kick.
Thrust is provided from the under-surface of the fins, the tips bending upward with respect to the diver's feet during the thrusting part of the stroke. The muscles that do most of the work are the backs and insides of the thighs.
A frog kick makes very little downward wash, so avoids the main drawback of the flutter kick.
However, the uneven thrust throughout the stroke and the slower repeat of strokes makes it less suitable for use in those situations in which strong continuous thrust or speed is needed.
You need to take care not to kick anything you are swimming alongside.
Many divers find it relaxing to use the frog kick as a general cruising kick, either by itself or alternating with the flutter kick every few minutes, so resting the muscles used by the other stroke.
The frog kick may not work very well with some types of fin.
- For general cruising
- When close above a coral reef or delicate marine life
- When close to a sandy or silty seabed
- To rest the muscles used by the flutter kick
- Inside large caves
- In narrow corridors of a wreck
- In a tight cave
- Close alongside a wall
- When a prolonged burst of speed is needed
- When swimming into a strong current
- On the surface
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The frog kick previously mentioned, and the short (or modified) version here, are two extremes of what is really a continuum of kicks. Take the full frog kick, but don't move your legs as far out, picking instead a length of kick that suits you and the circumstances.
At the extreme, the movement of your thighs and knees is very limited, and it is the calves and a flick of the ankles that do all the work.
From picture (1), the fins slip through the water out and sideways through (2) and (3) until they are ready to kick at (4).
Forward thrust is then provided by twisting the fins so that moving them back in pushes water back with the underside of the fins, as shown in picture (5), completing the stroke and leaving the diver ready to start again at picture (6).
The short frog kick provides very little thrust, but it is all forwards with no wash up, down or to the sides. It also keeps the fins closely in line with the diver's body.
These two features combined make it ideal for use in confined spaces, where a diver does not want either wash or the fins themselves to stir sediment or damage any delicate marine life.
The short frog kick is also popular for those exploring inside wrecks and caves, and among photographers who need to get closer to coral reefs and other marine
life to take photographs while ensuring that their fins do not disturb anything in the process.
Once again, the short frog kick may prove not to work very well with some types of fin.
- Inside wrecks
- In caves or any confined space
- When close above a sandy or silty seabed
- Close to a wall
- When manoeuvring near delicate marine life
- For stability, often used with backwards kick
- When finning against a current
- When speed is needed
- On the surface
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The finning backwards kick is never elegant, but can be useful in situations where you need to move away from something while continuing to look at it, or where you need to reverse course for a short distance without turning round.
Fins are not designed to work backwards.
The whole technique depends more on clumsily scooping water than on any refined hydrodynamic principle.
Starting from picture (1), the fins are turned out and as square to the leg as they can go (2).
In (3), the legs are then spread out and the knees bent to scoop the fins forwards with respect to your body, pulling you backwards in the water.
The tricky part comes in (4), where the fins are rotated sideways to the water so that they can be moved back to the starting point without pushing you forwards again and undoing all the work, (5) and (6).
The scooping is done with the upper surface of the fins, bending them downwards relative
to your feet.
The backwards kick is almost a complete reverse of the frog kick, the fins working through the first half of the kick and then slipping back through the water in the second half.
- When you need to move away from something while looking at i
- When you need to move backwards and must not touch anything
- When you need to move back while handling a reel or camera
- To reverse out of holes
- For stability when you don't really want to go anywhere, partnered with the short frog kick
- As a general cruising kick
- Against a current
- When speed is needed
- For long distances
- When you need to see where you are going
- When fin tips could kick anything at the outer reach of the kick
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This asymmetric kick combines aspects of both the flutter and frog kicks. Divers who haven't tried it before are often surprised by how much thrust can be generated by a long, lazy split kick.
One leg is dedicated to the upper part of the kick, the other making the lower part. Starting from picture (1), in the example the left leg is used as the upper leg and the right leg the lower.
The upper leg is moved upwards as in a normal flutter kick, the fin slipping through the water and providing no thrust during this part
of the cycle. Meanwhile, the lower leg makes a downward kick, bending the knee slightly as in
a frog kick, but keeping the fin movement downwards so that it can thrust against the water (2) and (3). This is not the main thrust stroke of the kick, but a sort of added extra.
From the extreme of the split (4), the legs are then brought together, the top of the upper fin and the under-side of the lower fin acting on the water to provide thrust. In picture (5), this can be seen by the fins bending away from each other.
The stroke ends with the fins being brought together one above the other (6), squashing the last bit of water out to provide the final bit of thrust.
The lower leg provides thrust through the entire fin cycle, while the upper leg provides thrust during the second part of the cycle. Because the fins are brought together, it is not practical to swap legs at the end of each stroke. Some divers favour one leg, while others will swap legs every 10 or so strokes.
The split kick works best with long and powerful strokes to provide high thrust, but suffers in that it cannot be speeded up, like the flutter kick.
This is a power kick, rather than a speed kick.
- For powerful cruising
- Swimming into a current
- When more thrust is required without increasing the kick rate
- To rest groups of leg muscles, switching legs every few cycles of the kick
- As an initial strong kick or two to get going
- Close to a silty or sandy seabed
- Inside a wreck
- Inside a cave
- When swimming close to coral or other delicate marine life
- When ultimate speed is required
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