I must be doing it wrong but the Tacho software at work flagged up an issue over this:
08:30 start. Max 3hr drive and breaks/other work
15:00 get to port and park in queue side of harbour, Select ferry mode and break.
20:00 drive onto boat 1min drive then stop, select ferry mode and break.
01:00 drive off boat for 30mins park in layby, select ferry mode put on break.
03:30 drive back to yard park up 06:30 break.
Im sure its something retarded on my behalf but oh well.