Many existing electronic lap counters require the swimmer to press a button on every lap. Such systems are often either built into a kind of wristwatch or wall-mounted. On the crowded lanes of a public pool, mounting a manually triggered counter to one end of the lane seems to be a bad idea, as there is no way to distinguish different swimmers.
Another more sophisticated type of counter relies on a wearable 3D-compass to deduce the number of laps by sensing a swimmer’s orientation. Unfortunately, such systems are not available as a product yet or at least not at an affordable price.
So in the meantime we’ll try to build a system that is usable, available and affordable.