Scalping Tickets for PT Ferry

Within minutes after my story came out the other day about a pilot reservation system for the Port Townsend-Keystone ferry, wily workmates were scheming about how to job the system. One idea was to reserve a bunch of spaces and then go and scalp the confirmation numbers at the dock or put them on craigslist.
The fact that half of the reservations can’t be made until the day of sailing prevent some abuse, although the day starts at 4:30 a.m. and somebody could get up early and try to grab them all up.
I would think the ferry system has already thought of this and has a way to prevent it.