http://en.wikipedia.org/wiki/ShipShips can usually be distinguished from boats based on size and the ship's ability to operate independently for extended periods. A commonly used rule of thumb is that if one vessel can carry another, the larger of the two is a ship. Dinghies are carried on sailing yachts as small as 35 feet (10.67 m), clearly not ships; this rule of thumb is not foolproof.
When you can no longer fish out of it with a rod and reel, it becomes a ship.:fish2:
Boat
A small vessel propelled on water by oars, sails, or an engine.
"a fishing boat"
Vessel
A ship or large boat.
Ship
A vessel larger than a boat for transporting people or goods by sea.
Yacht
A medium-sized sailboat equipped for cruising or racing.
A powered boat or small ship equipped for cruising, typically for private or official use.
http://en.wikipedia.org/wiki/Ship
It's situational:
When paying taxes, registration or moorage, it's just a little boat.
When trying to sound as though I'm an expert mariner and know it all, it's a vessel.
When trying to tell others how seaworthy and stout she is and how expertly I maintain her, it's a ship.
Whey trying to pick up chicks, it's a yacht.
Southkogs nailed it!
Southkogs nailed it!