Thanks for the response - very informative as always

I would probably be on Dual Watch on the VHF using 16 & 72 anyway listening to any chatter.
I do like the idea of using 13 in my scenario above which would probably be very quiet.
I'd use 72, 73 or 77 if I just wanted to have a natter!!
I've been down past Gladstone in the dark & watched one of these monsters weigh anchor & head into port - they don't muck about. I didn't have a functioning VHS that time tho!!