There is already a "move to" function, and that's all the patrol function would need to be usable. Zone of control is not an issue; units need to be hostile to exert zone of control, and spotting a hostile unit would wake the patrolling unit. If the unit can't get where it needs to go, it will wake up and ask for new orders, just as with the current "move to" function.
Of course the automated patrol won't be optimal and the player could control it better manually, but that's as it should be. But moving a ship up and down the coast repeatedly is pretty tedious.
Of course the automated patrol won't be optimal and the player could control it better manually, but that's as it should be. But moving a ship up and down the coast repeatedly is pretty tedious.