I believe that you must be at least 10 before you don't have to wear a life jacket in a boat, although I'm not entirely sure , I'm pretty sure that this is the answer. Correct me if I'm wrong!
In the state of PA, you have to be at least the age of 12 years old.
10 years old
Whenever the boat is underway, properly sized PFDs must be worn by children under 13 years of age in North Carolina.
In Hawaii, children 12 and under must wear a properly fitting PFD while underway!
Whenever a boat less than 26 feet is underway, properly sized PFDs must be worn by children less than 6 years of age in Florida. Whenever the boat is underway, properly sized PFDs must be worn by children 9 years of age and under in Georgia.
12
Under 13
Under the age of 13.
12 years of age and under.
6 years
11 and under.
13 years old and under
Age 13
12