I mean the 9.00 oclock ferry which only takes 3 hours

Maybe. I guess you will at least have to pay the usual surcharge that anyone has to for this ferry above the normal one. They will certainly be able to tell you at the port. or maybe the site if you try to do the online RES will tell-not, only with extra to pay or yes.

But the regular people who answer most Qs here know a big lot over trains etc but none has ever used this ferry pass and the minimal nr of users-as seems normal for these youngsters, never bother to give back some info or experience they may have found.

Hello! Thank you for your question. Please accept my apology for the late response.

I would recommend checking this with the Ferry company. 

Phone: +30 (0)210 891 9800

E-mail: helpdesk@attica-group.com

Information about timetables can be found on:

https://www.bluestarferries.com/en/travel-with-us/domestic-lines/timetables.html

I hope this helps!
Kind regards,

Annie