snipped quote "I think that if one vessel can be carried by another
vessel, it's a boat. The one doing the carrying is a ship."

This is exactly the definition that the chief bosun's mate who was my
company commander in boot camp taught me almost 35 years ago. But
look at the photograph of the Blue Marlin at http://www.sailfinalstraw.com/Dockwise/Dockwise.htm
and you can see that the definition is getting a little uncertain.

I think Chief Padgham was from destroyers (although it was a long time
ago) and the picture notwithstanding, I'm not too sure he would
appreciate a ship he served aboard being called a "boat".

Take care . . .

John