Not really. As long as they had One Control Channel it would still work.
For a Single Site Trunk you only need One Control Channel. They get programmed for Two to plan for failure and originally many had 4, so the transmitter was not broadcasting 24/7 and they could rotate.
Many of them now [Public Safety] in New England have moved to only two [One Primary and the other as a Back-up] Control channels.
Yup, best time is Arrival / Departure. Along with VHF Marine as the Pilot arrives, or they have a drill [Lifeboat] and ask the USCG for permission to run a Lifeboat drill. Manytime this is the only way you will
find the Emergency Channels.
Arrival is best, as they announce how close to the dock. Even with the Official Band Plan , it will depend on the home country [not registered, but Built]
I have found leaving the following works well [and yes, some are GMRS] for the basics
457.5000 457.5250 457.5500 457.5750 457.6000 457.6250
467.5000 467.5250 467.5500 467.5750 467.6000 467.6250
467.7500 467.7750 467.8000 467.8250
Any can be the Repeater. Don't forget the 12.5 Khz splits in-between as well.
Reports from Europe indicate a lot of the splinters being paired into repeaters as well.
It's been awhile since the following were found [San Pedro regulars]
RCCL Vision of the Seas [Sundays as well]
RCCL Monarch of the Seas
I'll go back and compare, but they must have kept the control channels the same, or it would be a big PITA to reprogram all of the radios.
One challenge I've observed is that it is very difficult to localize which ship is using which frequency. It is much easier while the ship is underway to localize frequencies, since there isn't so much background RF. It turns out that USA ports have LOTS of RF, so harder to figure out who is who in port.
One suggestion is to start with the Maritime bandplan from the FCC. It will at least get you in the ballpark.