Most beginners are taught one fin stroke. It is the easiest and probably the most efficent kick, known as the scissor or flutter kick. You lock your legs straight and all motion is from the hips.
As a result, most fins are designed to work with this specific kick, with innovations such as channels along the fin so they form a U-shape when used, which channels water backwards instead of downwards, enhancing the power of the kick.
However, the flutter kick is good for one thing, and one thing only: Going forwards in a straight line with minimal effort. It does not lend itself to any other maneuvering.
For instance, if you're doing a there-and-back type dive. When you decide to turn around, how do you do it? Flailing around with your hands? Roll onto one side and struggle around? A big, long curve?
It's awkward, isn't it? And if you're doing diving in any kind of confined space - a wreck, a cavern, even between two walls of coral - then it's not acceptable. Wrecks can have sharp edges. Corals can sting, and can be damaged by clumsy divers.
Just simply turning to face your buddy can be awkward. If you loose sight of your buddy and have to do a 360 degree search, how easy is it for you to do it? How much silt do you kick up?
There is a better way!
There are many other kicks. However, the single most useful, versatile kick is the Frog Kick. This one style of finning gives you the ability to fin along without kicking up ANY silt from the bottom. It allows you to turn on the spot without the slightest difficulty, again without kicking up any silt. It even allows you to fin BACKWARDS, which can be a very useful skill in close quarters.
Sounds good, doesn't it?
So how do you do it? Well, it's actually pretty easy. And there are several varieties.
If you just want to give it a try, the simplest version is this:
Get yourself neutrally buoyant, a foot or so above the bottom. Hover horizontal in the water with your legs out straight.
Now, with your fins perfectly flat, spread your legs. No force should be generated by your fins in this movement - your fins should cut through the water edge-first.
Then, twist your ankles and bring your fins inward. This is the part of the kick that generates force. When your fins meet, they should make a V-shape. All propulsion is generated by the underside of the fin.
As you can see in the diagram, because your fins are tilted upwards relative to the direction of movement, the water you displace will be channeled up, rather than down. This is why frog kicking never kicks up any silt from the bottom.
However, that's not a proper frog kick. That's just the easiest way to prove to yourself it works. To get the most out of it, you need to modify it a little. It takes a little practice and co-ordination, but what you do is:
Float horizontal in the water, legs together. This time, though, bend your knees to be at right-angles to the rest of your body. The most common mistake is to bend your legs at the hip as well - you have to consciously keep your legs straight.
Now, as before, part your legs, with your fins cutting through the water.
Then, angle your fins, but as well as bringing them inwards, straighten your knees as well, so your fins go backwards as they come together. Then, when your feet are together, bend your knees up again.
This channels the water far more efficiently backwards, giving you more forward thrust, but still not kicking up any silt from below.
So that's the Frog Kick. As you'll realise when you first try it, keeping the right posture and co-ordinating the "inwards and backwards" motion properly makes this a kick that isn't really suitable for novice divers.
But what about turning? I hear you cry. Well, frog kick-based turns really are very simple once you've got the basic frog kick mastered - All you really do is frog kick with just one leg.
To turn, float horizontally with your knees bent, just as before.
Now, use the opposite leg to the direction you want to go - left fin to turn right, right fin to turn left. Keep the other leg immobile.
Cut the one fin outwards, with no propulsion as always. Then, angle it inwards and sweep it back in.
Just like that, you turn a circle, on the spot, and with no silt.
Isn't this graceful rotation infinitely better than floundering around with your hands or swimming a big curve?
So now that you can swim along without kicking up any silt and turn on the spot while gracefully hovering horizontally in the water... what about going backwards?
This is the hardest part, even though it really is just a reverse frog kick. It does take a lot of practice - it took me months! However, once you get it right, it's like throwing a switch - I went from unable to move even slightly backwards to doing an entire length of the pool in reverse in the space of a single hour!
I find it helps to be slightly heads-up to reverse kick. However, I advise you to start out horizontal and then alter your position as you find you need to.
As usual, you should have your legs together, knees bent. Then, exactly the opposite of the usual frog kick: angle your fins, sweep them outwards, then flatten them and cut them back together. All propulsion is done by the top side of the fins, and on the outward stroke, not the inward.
It takes practice, but it's worth it in the end.
However...
The reverse stroke is not a fast or a powerful stroke, no matter how much you practice. Half-frog turns are never going to be noticeably faster than a quick flounder around. The chances of winning a race against a flutter-kicking buddy by using the frog kick are slim.
Unlike the flutter kick, the frog kick only supplies propulsion half the time. You don't gain speed or power by using it.
But scuba diving isn't a race. It's a lesiurely sight-seeing trip. The faster you go, the less you see. The more silt you kick up, the less you see. And the more control you have, the more confident you'll be and the more you'll enjoy your dive. A diver with good buoyancy control and mastery of the above fin strokes is ready for anything. With these simple skills, you can spend your entire dive comfortably floating horizontal, navigating into and out of any space big enough to admit you without any effort, any floundering, or any silt. You'll also use less air doing it all.
Sounds good, doesn't it?
A picture is worth a thousand words, they say. The 5th Dimension website has a few videos of people doing the backward and the frog kicks.
The GUE courses they run teach these strokes, as well as helicopter turns, which allow you to turn in an even smaller space.
