That all depends on a number of things. How clear is the water and how deep as well as how far are you needing to bring the fish from. If the water is clear and you know you are anchored in a spot with fish holding cover near then not much light will be needed to get their attention. If there is a full moon you are competing with you will need as much light as you can get and it still may not be enough. Typically guys want as much light as they can get.