I have traveled on many ferries, cross channel, aberdeen Lerwick, inter island (if its rough they tell you to stay with it, to hold it up), Belfast, liverpool etc ect, I just park how and where the staff tell me, put the bike on whatever stand they tell me and walk away and leave them to it

. Never had a problem, they know what they are doing and have secured thousands of bikes in their time, its their job! Many ferries have different systems, some secure to side rails, some to cables on the floor, some to floor rings, wheel clamps etc, they know whats best for their system, main or side stand (assuming you have both) If you stand over them you will probably never be 100% happy with what they do, for me, my advice is dump the bike and walk away and leave it to them.