Lets be honest, the difference between a ship and a boat depends on a number of factors, including where you are. This is almost a philosophical question as some vessels could be a ship or a boat or both. I shouldn't answer the question, but really... whatever floats your boat? Ships are big and complex, boats are usually smaller and more basic floating craft.
On to the real question. Location and surroundings can make a stagnant image, more interesting. I agree across the board, motion or signs that something is in motion if that's the situation, will make images more interesting. Showing the use or what the boat/ship is doing or designed for is also nice.
A close up of the side of a boat, at a dock, with no one and doing nothing, isn't really going to be very interesting. Like someone said, a parked car isn't as good as one driving. But back to, where is it parked, is there something more to the subject than, this is a boat/ship?
Concept, function, purpose, setting, I think can be useful for making more interesting and attractive images. Images that simply say something visually can work as well.
This is a barge (which is what?) being pushed by a tug boat, which seems to be big and powerful and has a crew, but it's a boat?