No to open carry in a boat (while the motor is running) it is classified as a vehicle under the vehicle discription statute.
After the new law takes effect on Nov.1 it will be legal under the new law.. only if the firearm is a "handgun"...
As far as from shore or public dock... a few varibles to consider (private property, dock location, etc.), but gennerally speaking I would say yes...
Outdoorsman1