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Common mistakes made during diploma swimming and how to avoid them - Error analysis

Discover the 10 most common mistakes in diploma-A, -B and -C and learn simple drills to correct them in 2 weeks. Incl. checklist & tips.

July 2025
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Instant overview: 10 common mistakes & quick fixes

#ErrorDiplomaImpactQuick fix
1Head too high on breaststrokeA / BBreath stress, low speed"Look-to-the-bottom" exercise
2Arms underwater on water kicksCDisqualification30 s water kick with ball overhead
3Blowing out too late ➜ oxygen debtAllStop after 25 mBubble play 3 min/day in bath
4Legs drop in backstrokeADistance not metKick-board-drill 4×15 m
5Head start not tight (B)BTime lossLand-head roller on mat
6Missing hoop under waterAUnderwater trip not metAiming point under hoop
7Losing shoes in clothes swimmingB / CDisqualificationDouble knot & 25 m test
8Wrong HELP attitudeCSurvival component insufficient3×60 s practice in shallow pool
9Short breaths in breast crawlB / CTime limit exceeded6-beat drill with snorkel
10Nervousness ➜ starting too soonAllExhaustion halfway through10-breaths focus ritual

Tip: Film your child two weeks before the exam (1× technique, 1× in clothing) to quickly spot the biggest mistakes.

1 - Faulty breathing & heading position

Many candidates blow out too late, come out on top with a "gasphap", hold the head too high and lower the hips. Thus the speed drops per stroke.

  • Bubble-drill: 3× 10 sec continuous exhale with face in water.
  • Look-at-the-bottom game: Instructor shows coloured card underwater; child names colour aloud.
  • Metronome beat: 25m breaststroke on 3-beat rhythm (exhale-arms-close-inhale).

2 - Incomplete leg stroke

Incomplete "frog-hop" in breaststroke and weak core in backstroke cost metres.

  • Kick-board overhead (armelet) - 4×15m pure leg stroke.
  • Wall-off exercise - legs fully extended against bathtub edge.
  • Home "plank" & "superman" - 3× 20 sec each night.

3 - Failure to meet time limit (condition)

B exam: 75 m ≤ 2:00 min. C exam: 100 m ≤ 2:45 min.

7-day build-up schedule

  1. Day 1: 4×25 m relaxed (swimwear)
  2. Day 3: 2×50 m + 2×25 m sprint
  3. Day 5: 4×25 m in clothes, 15 s rest
  4. Day 7: Test distance in exam outfit

Still struggling? Book a private interval session.

4 - Wrong start & shutdown

  • Landhead roll: Tight chin-to-breast, practice 10× on mat.
  • Streamer jump: arrow shape at entrance, arms tight against ears.
  • Video analysis: slow-motion shows or knees hit first.

5 - Underwater orientation errors

  • Laser line: duct tape as "rails" on bottom towards ring.
  • Bubble tunnel: Instructor creates bubble trail - visual line.
  • Tag underwater: Trains calm & sense of direction.

6 - Apparel swimming pitfalls

  • Double-knot test: 25m swim; is shoe falling out? Tighter knot.
  • Weight check jacket: wet coat ≤ 10 % body weight.
  • Dry-run: Practice at home in the bath to feel resistance.

View full NRZ clothing requirements on the requirements-page.

7 - Water kicking & floating

  • Ball overhead + water kick 3×30 s.
  • Bottles of water in each hand 3×20 s (extra weight).
  • In HELP position blow out slowly, head neutral.

8 - Mental pressure & exam nervousness

  • 10-breath ritual: in 4, out 6, 10 rounds before start.
  • Visualisation: eyes closed, run through track in slow-motion.
  • Mini-exam at home: put on exam outfit, follow sequence out loud.

9 - Checklist: the last 7 days

ByeFocusAction
7Condition2×50 m in clothes, 30 s rest
6TechnologyVideo analysis breast & backstroke
5Start10 head jumps in a row
4BreatheBubble-drill + quiet breath 5 min
3ClothingDouble-button & coat-weight test
2Rest200m loose swim, sleep early
1Bag-checkSwimwear, clothing set, diploma form, water bottle

Summary & next step

Frequently asked questions

Children can start swimming lessons at Zwemclub ABC as early as 4 years old. So they learn to swim safely from an early age.

How big are the groups during swimming lessons?

Our groups consist of a maximum of 6 to 8 children per instructor. This ensures that each child gets enough personal attention.

Is it possible to take private swimming lessons in Amsterdam?

Yes, at Zwemclub ABC we offer private swimming lessons with individual attention, suitable for both children and adults.

On average, how long does it take to get a swimming certificate?

Achieving the A diploma takes 12 to 18 months on average. With turbo swimming lessons, it can be done within 2 weeks.

What is the advantage of turbo swimming lessons at Zwemclub ABC?

Turbo swimming lessons help you or your child get the diploma faster. Ideal if you're short on time or want to get swimming skills quickly.

Can I take a free trial lesson first?

Absolutely! You can always take a free trial lesson with us without any obligation. That way you can find out immediately whether Swimming Club ABC suits you.

Where do swimming lessons take place in Amsterdam?

All swimming lessons at Zwemclub ABC take place at the heated De Mirandabad swimming pool, centrally located in Amsterdam-Zuid (near Europaplein).

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Would you first like to try if our swimming lessons suit you or your child? Then sign up for a free trial lesson! You will get to know us, and we will help you on your way to swimming certification right away.
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Prefer a trial lesson first? You can do so again after the holidays.

Common mistakes made during diploma swimming and how to avoid them - Error analysis