This says "Ferry Boats" not boats.
When we boarded the ferry from the TTC to MK, the CM asked guests to put their masks on.
When we took a boat from MK to WL and later in the trip from MK to GF, we were told to wear our masks. On the boat from FL back to MK, a teenaged boy and his father took their masks off when they got on the boat. The captain told them they had to wear them or get off the boat. They got off the boat.
I can see if they allow people to go maskless on the ferry but not regular boats. Most of the boat seats are inside.