In Europe each boat has a classification as to what it is capable of:
A Class A yacht ( boat ) is a vessel that is built to navigate the open ocean and surpass a force 8 on the Beaufort scale and surpass waves higher that 4 meters. These yachts are constructed to be self sufficient in hostile seas.
A Class B yacht ( boat ) is a vessel built to navigate on the offshore waters (200 miles and less) and can substain UP TO force 8 and waves UP TO 4 meters.
A Class C boat is a vessel built to navigate inshore such as lakes, rivers, bays and close to the shore and can sustain UP TO force 6 and waves UP TO 2 meters.
A Class D boat is built for protected or sheltered waters such as canals, rivers, small lakes and sustain a force 4 and waves UP TO .3 meters (less that 1 ft).
These are class D motor boats--waves up to one foot.