Excise tax racket?

[NewEnglander]

I just moved aboard for the first time. I paid excise tax to the city of Boston, which is home base.

I came into a marina in Winthrop (near Boston) for several days and received a ticket from the harbormaster for failure to have both a Winthrop waterway sticker and a Winthrop excise tax sticker. (Total fine $150)

As far as I understand, I owe excise tax to the municipality I primarily store my boat, not every single municipality I visit. The same with the waterway tax. (Do correct me if I'm wrong!)

I can contest the ticket in court, of course, but like I said... I'm on the go and may not be in the state by the time a court date rolls around. Has anyone else run into this problem?