Who is the "son of a bitch" that Dick Best is referring to?
While on board a plane, Dick Best contacted his flying squadron after seeing enemy warships:
Dick Best: God damn it. That magnificent son of a bitch actually found them.
Dick Best: (on radio) All right, boys. Bombing Six, we've got the first bastard in line.
Who is Dick Best referring to?
He's clearly referring to McClusky, who in an earlier scene spotted a single carrier, which he speculated was trying to catch up to the rest of the fleet. They decided to follow it and indeed came upon the fleet.