One of the strange things about Deep Zone is that the author, Tim Green, has chosen not to describe the physical appearance of his main characters. On page 140, he does say that Troy is wearing a blue jersey with white numbers, but he provides no clues as to the color of his eyes, hair, or skin. On page 158, Tate tells Ty that he and Troy White look alike (they will later find out they are actually cousins), but unfortunately, the author doesn't tell us what Ty looks like, either.
One reason for this may be, as he states in his dedication, that the main characters are based on his sons. He might not want to embarrass them by giving away their identities.
He does provide one hint as to what Troy White might look like. On page 160, he writes that Troy plays in defense for his football team as a free safety. The free safety is the last line of defense, so he must be a strong and relatively large man.