This means that the battery is discharged down to 10.5 volts over a 20 hour period while the total actual amp-hours that it supplies are measured. Sometimes ratings at the 6 hour rate and 100 hour rate are also given for comparison and for different applications.
Pool meets are usually no more than 4 hours, but beach meets last about 7 hours. It depends how many events are in the meet. And then if it is a really big meet (like a tournament kind of) it can last days. Hope that helps.
One of the simplest forms of multisport, aquathlon consists of swimming and running. The official distances for the annual ITU Aquathlon World Championships are a 2.5km run, 1km swim, and 2.5km run. This can change if the water temperature is low, and in this instance the race becomes a 1km swim followed by a 5km run.