Enemy Pirate Ship AI

Hello, I am making a pirate game. I'm trying to ac$$anonymous$$eve an enemy pirate s$$anonymous$$p AI. I've made an attempt but then scrapped it because it was terrible. Basically one idea I had was for the s$$anonymous$$p to follow you a certain distance, but when it gets into firing range, circle the target with one side facing the target. I've tried transform.RotateAround();, but for some reason when I try to subtract 90 from the y-axis to get the side to face the target, it just stays at a fixed (0,0,0) angle.

Any help would be greatly appreciated!