The first 40 people are definitely fine. There are several ways for the remaining 12 people to charter a boat, among which renting one big and three small is definitely the highest, so it is not considered. The rest is to rent two big ones, one small one and four small ones. The rent for 4 boats is 420 yuan, and the rent for 2 big boats 1 empty seat is 425 yuan, so the charter scheme is 8 big boats and 4 small boats.