BUT (and I agree This IS Stupid) -*you* have to find it. And alter.

On my car, for ex: if the hood is open, the alarm can't arm. (Not so re trunk.)
Permanent disable: turn over, remount the hood switch so it never makes up.
Smarter: run small zipcord to passenger compartment - put in any old switch.
(Needn't even cut a wire - just disconnect, use ~ terminal on extension wire, etc.)
'Course Muricans don't know what a switch is / or how/why one might be used.

One can improvise on other versions: for ex. a similar switch in a(ny) 'door closed' wire - probably wouldn't let other alarms arm, either.

The people on the ferry could just not Lock their rolling treasure domes.
Maybe not practical - what with the $10K Bose/JBL/Rolex and other stuff that would have to go in the trunk.

As I said - Stupid that there isn't an On/Off for these suckers - the ferry being only one obvious need. Stupid, thus -- not surprising anymore.