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.
SWIM LESSON TIPS: 1  Each swim lesson for infants and toddlers should last only 15 minutes; up to 30 minutes for 3-5 year olds, and up to 45 minutes for children over 5 years old.  The ratio of swim teacher to swim student should be 1:1 for children under 5 who have not reached swim stroke and treading water proficiency.