The Pool With No Splits: Vietnamese Swimming's Data Gap

In April 2026, at the national swimming championships in Hue, I sat in the stands with three phones running three different timing apps. A male swimmer finished the 200m freestyle. Three screens showed three numbers: 1:52.18, 1:52.34, and 1:51.97. The gap between the highest and lowest reading was 0.37 seconds — enough to change a ranking, enough to swap hands for a SEA Games slot. The organizers published no split sheet. No stroke-count system. No analysis cameras. Just three numbers that agreed on nothing, and a two-hour argument among coaches afterward. I sat there, recorded everything, and realized: the biggest problem in Vietnamese swimming is not in the pool. It is that nobody measures the pool.

I work with data for a V.League club. People ask why a football data analyst writes about swimming. The answer lies in the first lesson I learned in 2026: a small GPS deviation taught me that verification is everything. When I turned to swimming, I carried the same question: which data exists, which data is missing, and what is that gap hiding?

Swimming differs from football at a fundamental level. A football match leaves thousands of data points: positions, distance covered, touches, xG. A swimming race leaves one number — the finishing time. The whole story of a 200m lane, from the dive start to the final wall touch, is compressed into a single result line. No splits, no stroke rate, no tempo, no stroke length. The analyst is stripped of nearly all raw material.

Worldwide, that is not the case. At the Olympics, each lane is recorded by electronic timing for every 50m, underwater cameras measure stroke rate, and software analyzes stroke length per lap. An analysis of Katie Ledecky states precisely that she lost 0.8 seconds in the third lap because her stroke rate rose from 38 to 42 per minute. An analysis of Vietnamese swimming can only say: Swimmer A was 0.4 seconds slower than Swimmer B. That is the difference between medicine with imaging and medicine with only a thermometer.

I spent six months collecting data from national meets in 2026–2026, aiming to build a basic split set for the men's and women's 200m freestyle. Of 47 national finals I tracked, only 9 published an official split sheet. The other 38 I had to hand-time — a minimum error of 0.2 to 0.3 seconds per lap, multiplied across four laps into a cumulative error of more than one second. One second in a 200m is the gap between gold and fifth, between an international slot and a seat at home.

I cross-checked three sources: the organizers' scoreboard, the commentator's recording, and parents' phone video. The three sources differed by an average of 0.41 seconds on every finish. When I showed this figure to a veteran coach, he laughed: anyone can see who is fast or slow in a pool, why bother with numbers. I understood the reaction. The coaches are not short on knowledge. They have simply never been handed data good enough to understand.

But one detail stands out. While swimming lacks splits, other sports moved ahead. Vietnamese athletics has had electronic timing at many national meets, with 100m splits published live on the scoreboard. Football has GPS. Basketball has play-by-play data. Swimming, the sport with the cleanest data structure of all, is the one that leaves the fewest traces. The problem is not technology. The phone in every parent's pocket on the stands can time to 0.01 seconds. The problem is that nobody considers it worth doing.

Compare two swimmers. Swimmer X swam the 200m freestyle in 1:53.2, with lap 1 at 26.8, lap 2 at 29.1, lap 3 at 29.8, lap 4 at 27.5. Swimmer Y swam 1:53.4, with lap 1 at 27.2, lap 2 at 28.4, lap 3 at 28.9, lap 4 at 28.9. On total time, X is 0.2 seconds faster than Y. On split structure, these are two entirely different athletes. X explodes early and late, collapses in the middle — a sign of speed without an aerobic base. Y distributes evenly and holds the final lap — a sign of a well-built base. In a four-year training cycle, X needs long endurance work, Y needs short speed work. With only total time, both receive the same program. That is the most expensive mistake a data-less swimming nation can make.

The same issue appears in heats and finals. At many national meets, organizers hand-time the heats and use electronic equipment only in finals. That means a swimmer can be eliminated from a final by the timer holder's error, not by their own speed. When everything is decided by a single number, and that number is measured by hand, the selection system becomes probability, not performance.

I once thought the problem was money. An electronic timing system for eight lanes costs a few hundred million dong, the price of a small foreign signing. But after talking with many coaches, I changed my mind. Money is the easy part. The problem is that nobody asks the question.

Here is where I have to be careful with myself. There is a strong temptation in the data profession: to believe that having numbers solves everything. I have seen it in football — clubs spend millions on GPS systems but never change how they decide. Data does not create victories by itself, only possibilities. I believe in numbers, but only after a number has passed three rounds of checks.

For Vietnamese swimming, I separate two layers. The technical layer: no split systems, no cameras, no software. That layer is solved with money. The cultural layer: the belief that the eye for people matters more than data. That layer takes far longer. I once watched a club ignore my 19-match analysis because numbers cannot replace the eye for people. That player scored 4 goals in 20 matches. Four months later, the sporting director was sacked. The table of numbers remained. It speaks for itself; I do not need to.

In swimming, the same thing is happening, but slower and quieter. Nobody is lazy. An entire ecosystem — coaches, parents, journalists, federations — has never been asked a question about splits. When nobody asks, nobody supplies. When nobody supplies, nobody learns to read.

There is a paradox I must acknowledge. The lack of data is sometimes justified by the phrase: swimming is an individual sport, it does not need complex analysis. But swimming is the sport with the cleanest data structure of all. No teammates, no opponents affecting you directly, no referee deciding the outcome. Everything is numbers. A pool cannot lie. Only those who refuse to measure let it stay silent.

What am I waiting for next? Not a new record. I am waiting for the moment someone, perhaps a parent with a phone, asks: which part of the race did my child swim slowly? When that question is asked often enough, the data will come. And when the data comes, the lane will start telling the story it has kept to itself for years. Data does not tell stories; it records everything so that I can tell them myself.