Describe the relationship of the old man and the boy. Is it a father and son relationship? (From "The Old Man and the Sea")

Santiago and Manolin share a mentor/mentee relationship.

Mandolin is Santiago's former apprentice, not his son. He used to work under Santiago, but Manolin's father made him stop and go work for someone else who was more successful because Santiago was having such a long streak without catching anything. Manolin continues to visit Santiago, however. He brings him food and even bait. It is obvious that Manolin cares for Santiago much like a father or even grandfather, and is doing his best to help the old man get by during his dry spell. 

Many of the lessons that Santiago imparts to Manolin are the types of lessons a father would share. They also share activities like a father and son, such as fishing and talking about baseball. Although we do not know Manolin's father, one cannot help but wonder if Manolin isn't closer to Santiago than his own father.