As a PADI Instructor, there is no requirement to start from shore dives. I've used Catalina mostly for OW. I know other instructors use the boats (Spectre included) for OW. It's the instructor's call. I have cancelled classes even on Catalina due to surface conditions. The focus is expected to be the safety of the students based on the dive conditions, class size and student capabilities (I'm more cautious with a single marginal student in class than with a group of college swim team).