I use 12mm on Madness so would say 12mm would be more than thick enough for your boat and 16mm definitely is overkill. I reckon if you had 10mm rode you could fit a full 220m coil in your locker.
Sorry no rope left from s/ton uni we must of had around 12/14 drums of the stuff over the years. They used it to lay expensive equipment on the sea bed and said it was to expensive to retest for insurance purposes. Also they couldn't sell it due to liability risks so gave it to us, some looked brand new. Brought it all back in my van 2/3 drums at a time.