So to solve this they just don't measure beyond hundreds (no human can swim fast enough that the distance they travel within 0.01s could make a difference). And thus can not use photo finish either as again the lanes are not guaranteed to be the same length.
https://interestingengineering.com/significant-digits-and-po...
edit: In other sports like running it is easy to have accurate track length as you just paint the lines after building the track so you can have it as accurate as you want (+photo finish). In swimming it just does not work like that.
Let’s say real times were 58.994999 and 58.995000 seconds. The first gets registered as 58.99, the second as 59.00. Actual difference is a millionth of a second, or, at 2 meters a second, 2μm.
I think they do this in swimming more because swimmers, certainly at shorter distances, more race themselves than their competitors. That’s a huge difference with road cycling, where typically the front riders in a sprint could get over the finish earlier, if they wanted to, but don’t want to do that, as, if they did that, their competition would tail them up to the last few meters and then jump over them.
Rowing is somewhat of a middle ground. They do use finish photos, even though there’s the same. “Tracks aren’t guaranteed to be the same length” problem as in swimming.
A famous example is the men’s scull final in the 2016 Olympics: https://www.olympicchannel.com/en/video/detail/mahe-drysdale...
I don’t understand why you think it’s easy to have accurate track length in running. Temperature may affect track length. A lot more importantly, I don’t think it’s even doable in events where runners all start in their own track but are allowed to move to the inner track after x meters. But again, it’s less important there because runners race against each other there more than in short swim races.
In swimming, the start and finish are both fixed physical objects that the swimmer must touch (though in all events except backstroke, the start is a bit weird because it's outside the pool).
In rowing, the finish line is an imaginary line much like cycling or running. While at the Olympics there are 'clogs' to hold the bows of the boats which drop down at the start:
https://www.polaritas.com/products-and-services/automatic-st...
a race official is always required to certify that the bows are aligned, which is why the gates are transparent (and the system includes video cameras to help this official).
In rowing you row between 2 imaginary lines. You don't even have to get the distance of these lines perfectly just make sure they are both in the same direction and neither boat gets the advantage.
With swimming you have to build a 50m long and quite wide concrete structure that has straight angles at all 4 corners and has perfectly straight walls. This is actually much harder to do then it sounds.
Nitpick: that is not correct. If the shape of the course is a parallellogram, the shortest course between the short sides is perpendicular to those sides. Teams in some of the lanes my be able to pick such a course. For example:
________________________________
/A B/
/ /
/ /
/C D/
——————————————————————————————
It is very unlikely they won’t hinder other crews if they cross all lanes, but they might just cross lanes of a few much slower boats.
That’s all theoretical, though. The net gain on a normal course would be very, very small, and buoys will typically hinder crews that would try this so much that it wouldn’t be worth it, to start with.
Also, for the true nitpicker, “the right direction” can be difficult. Drawing equidistant lines on a globe isn’t trivial (I don’t think the effect will be large for a 2km course on earth, though)
How do you achieve a million frames per second? Even analog input (like touching - which would be capacitive [hence more tolerances]) will have a very hard time registering that, just based on cable and PCB traces length, temperature differences (which affect silicon and resistance in general). 7 digit precision is a non-trivial task for non-controlled environment. For example 8.5 digit voltmeters take one 1 minute for a single measurement and they have to have extremely good temperature controls.
Then for the microsecond precision you have to consider the speed of sound just to propagate to participants to hear the gun.
Side note: my HP 3458A can do a small handful of 8.5 digit DCV measurements per second.
It would be crazy expensive to make the pools to such a small tolerance, perhaps, but it is not the length of the pool that actually counts, is it? It is the distance to the touch pad that counts.
Would it be crazy expensive to make the touch pad mounting system adjustable so that the position of each lane's pad could be adjusted to millimeter or even sub-millimeter tolerances?
But yes in general new competition pools are built to be slightly larger than 50m and you just adjust the pads at the ends.
(Of course, this would totally ruin the sport for spectators.
Following this logic, for any sport with no interaction, everyone could just stay home and run around their own track whenever they feel like and just send in their times to a central record keeper.)
https://www.telegraph.co.uk/content/dam/news/2016/08/13/drys...
(Drysdale is in the black boat).
