What determines the size of propellers on an aircraft carrier (or any other large ship)?

Question

If for example, the props are 30 feet in diameter, why not say 35 feet? Is there a reason for one size vs another size? Is there a 'set formula' for choosing one diameter over another?

Answer 1

all boats>size,weight,engine h/p

Answer 2

its the size, weight and performance that they look for.. also cavitation.. even if its a carrier they don't want it to make anymore noise than it do's