The finals include the top scoring boats from the weekend.
A quick note here: Depending on the number of boats competing and the conditions of the boats at the end of the weekend, there may be what's called a "Provisional Heat" before the finals. This heat is made up of boats that didn't have enough points to qualify for the final heat. It's kind of a last chance/second chance for boats to get into the final race. Win the Provisional and you'll get a seat at the table in the finals. But not a good seat.
Finals are five laps and a whole lot of fun to watch. It's really an all or nothing type event. The winner of the finals is named champion of that race for the weekend and keeps bragging rights until the next year's race.
You can win the finals, but still not have the most points for the weekend, depending on how you did in qualifying and previous heat races. These points will go towards the National High Points championship. Points are cumulative throughout the racing season.