Coach or first name?

[SCalScoreKeeper]

Hey Guys,
As a scorekeeper in Southern California I go by this rule when interacting with coaches during a game-

My school's coaches:
Varsity Boys-Just call him and assistant Coach (Insert Last Name)!
Varsity Girls-First Name Basis

Other School's Coaches-Applicable only when I am only book for that game or when visiting book cannot get their benches attention:
First Name Basis and if not heard go to Coach (Insert Last Name)!