Are they necessary? No, not really, unless you are going for a world record. Should you learn how to do them? Yes - you should try. Among other things, they take some strain off of your arms and shoulders, add an element of breath control to your workouts (both a psychological and a physiological aspect), and they look cool!
Where to begin the flip? If you swim towards the wall and extend your arm straight out, towards the wall, as if you where going to touch the wall at a finish, you should begin the somersault just before your hand touches the wall. Any closer than this and you may crash into the wall. Further out, and you will have to glide in after you have flipped. As you develop your turn technique, you may adjust this distance out a bit further, but the turn should be no slower than the swim - you do not want to waste time gliding or floating (unless you need a break ;-)
Some more tips:
- Do only a half somersault.
- As you "flip" look at your knees - try to bring your eyes and knees together - good "tuck" position.
- Bring your heels in, towards your posterior.
- Remember to blow air gently out your nose, unless you want a snout full of water.
- Feet land on the wall, toes pointing up, your back towards the bottom of the pool, your belly towards the ceiling/sky. If you were on land, you would be on your back.
- Push off the wall, still "back towards the bottom" of the pool, belly towards the sky.
- Just as your feet leave the wall, begin to twist towards the belly down position by looking (with your eyes only - don't twist your head) in the direction you wish to rotate.
- Your arms should be streamlined, hands together, straight, pointing in the direction you are traveling (a streamlined position).
- A tip from a reader - as you flip, push down with the palms of your hands to push your feet over your head (I tried the flip turn for years and until someone told me this important step I really looked awkward doing it. Once I realized how easy it made the turn when both arms were by my side and I pushed down really hard I then discovered what I thought was the real secret to a successful flip turn - Frank S.).
Each swimmer has a little different approach, and they are all probably OK. You may get a bit dizzy at first; either stop practicing so many flips at a time, or try to watch a fixed spot - like your knees - while you do the flip. Which turn works best for you is the one to use; try different things, find one that is comfortable, and practice, practice, practice. I think you will find that flip turns are not as hard as you may have thought; soon you will be doing them as well as an Olympian. If you use visualization techniques, you may get even better results.
More on Swimming Turns:
- Swim Turns, Part 1 - Open Turns
- Swim Turns, Part 2 - More Open Turns
- Swim Turns, Part 3 - Breakouts or Surfacing
- Swim Turns, Part 4 - Freestyle Flip Turn Basics
- Swim Turns, Part 5 - More on Freestyle Flip Turns
- Swim Turns, Part 6 - Backstroke Flip Turn Basics