For those unfamiliar with Pursuit racing, this is the way it works...
Based on the handicaps of the boats, and a set sailing time for the slowest boat, each class has a predefined start time, which should in theory mean they would all finish exactly together at the end of that set time.
So the slowest boat sets off first, then the quicker boats set off in order, with the fastest last, "in pursuit" of the boats in front of them. The boat in front when the time finishes is the winner, so you can actually see where you are at the end of the race based on how many boats are in front of you. The race will be started from the club line, but can be finished anywhere on the course depending on where the lead boat is when the time is up. The rescue boat will then run down the fleet making a note of the order at that time.