Among the three castaways, Louie is the unofficial leader. Why? * He is the strongest one physically. For instance, he was the only one capable of jumping in and out of the raft to escape strafing from the Japanese plane.
He is very creative. For instance, he created a hook out of his lieutenant's pin and used it to catch a fish.
He enjoys great lucidness (clearness) of mind. For instance, he remembered his family's tall, yellow dog from his toddler days; he had never thought of the dog before.
All of the above.