# Competitive swimming and lengths of pools: what is the acceptable variance? **URL:** \ **Category:** Factual Questions\ **Created:** [July 3, 2003, 1:10pm UTC](https://boards.straightdope.com/t/competitive-swimming-and-lengths-of-pools-what-is-the-acceptable-variance/186011 "2003-07-03T13:10:38Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![RTFirefly](https://avatars.discourse-cdn.com/v4/letter/r/c77e96/32.png) [@RTFirefly](https://boards.straightdope.com/u/RTFirefly)\ **Post date:** [July 3, 2003, 1:10pm UTC](https://boards.straightdope.com/t/competitive-swimming-and-lengths-of-pools-what-is-the-acceptable-variance/186011/1 "2003-07-03T13:10:38Z")
[Link:](http://www.washingtonpost.com/wp-dyn/articles/A1150-2003Jul2.html?nav=hptop_tb) > [@](#): > > Ten national high school swimming records set at the Virginia state championship meet in February will not stand after post-competition measurements showed the Virginia Beach pool that hosted the event is short of 25 meters by less than one-half inch. I certainly understand the need for exactitude with respect to competitive courses. But (puts on statistician hat) there’s variance in _everything_, no matter what lengths one goes to avoid it. So just what _are_ the official tolerances regarding the lengths of competitive pools? A tenth of an inch? A hundredth of an inch? This inquiring mind wants to know what levels of exactitude hold in pool-making for this level of competition - which, I’ll note, is high school, and not the Olympics. One-half inch doesn’t sound like much to me, and proportionally, it’s pretty small too: it’s less than 1/1968 of the standard 25-meter length of the pool. In a sport such as horse racing, your starting position can probably add that much to your trip; 1/1968 of the Kentucky Derby distance is 3 feet, 4 inches, and a horse starting from the outside probably does have to run that much further than a horse starting from the rail. So it would _seem_ to me to be the sort of margin of error that would be within competitive tolerances for lower levels of competition, at least. But I’m ignorant of the standards of this particular sport, so I could be wrong. So help me out here, guys. ---
**Author:** ![chukhung](https://avatars.discourse-cdn.com/v4/letter/c/e79b87/32.png) [@chukhung](https://boards.straightdope.com/u/chukhung)\ **Post date:** [July 3, 2003, 4:06pm UTC](https://boards.straightdope.com/t/competitive-swimming-and-lengths-of-pools-what-is-the-acceptable-variance/186011/2 "2003-07-03T16:06:16Z")
OK, as I understand it, international swimming competitions come under the purview of FINA (“La Federation Internationale de Natation”). On their website, they have the rules for facilities that are to be used for FINA-sanctioned competitions. On this page, [http://www.fina.org/facilityrules\_2.html](http://www.fina.org/facilityrules_2.html), it says > [@](#): > > FR 2 SWIMMING POOLS > … > FR 2.2 Dimensional Tolerances > … > FR 2.2.2 Against the nominal length of 25.0 metres, a tolerance of plus 0.03 metre in each lane minus 0.00 metre on both end walls at all points from 0.3 metre above to 0.8 metre below the surface of the water is allowed. These measurements should be certified by a surveyor or other qualified official, appointed or approved by the Member in the country, in which the pool is situated. Tolerances cannot be exceeded when touch panels are installed. If I’m reading that right, it’s saying that a regulation pool must measure between 25.00 meters and 25.03 meters, i.e., a little long is OK, but a pool _can’t_ be shorter than 25 meters. Of course, the rules for facilities sanctioned by the Virginia state championship may be different than those used by FINA. ---
**Author:** ![RTFirefly](https://avatars.discourse-cdn.com/v4/letter/r/c77e96/32.png) [@RTFirefly](https://boards.straightdope.com/u/RTFirefly)\ **Post date:** [July 3, 2003, 5:31pm UTC](https://boards.straightdope.com/t/competitive-swimming-and-lengths-of-pools-what-is-the-acceptable-variance/186011/3 "2003-07-03T17:31:09Z")
Ah, so the variance wasn’t the problem (as it’s OK for the pool to be over an inch longer than 25 meters); it was that the acceptable interval as a whole runs long. Well, that’s fair enough. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [July 3, 2003, 8:53pm UTC](https://boards.straightdope.com/t/competitive-swimming-and-lengths-of-pools-what-is-the-acceptable-variance/186011/4 "2003-07-03T20:53:46Z")
I’ll bet that the key problem with the pool in question was that the length did not account for installed touch panels. Note that the rule quoted above states that “Tolerances cannot be exceeded when touch panels are installed.” The touch panels used in my high school swimming competitions were about 1-2 inches thick. If the pool in question was between 25.00 and 25.03 meters long _without_ a touch panel, the subsequent installation of a touch panel may have sufficed to bring the length to less than 25.00 meters. (A touch panel, for those who may be wondering, is an electronic pad at the end of the lane that stops the timer when hit by a swimmer’s hand. It is used to determine swimmers’ times, and thus, the winner of the race.)