It's pretty natural that if you are watching a boat go by, you turn your head to follow it. The camera is no different. The Track to Constraint command lets you do just that:
Select the camera with theRMB.
Press the Shift key and theRMB to select the boat.
Press Ctrl+T to get the tracking menu. Select Track to Constraint.
Press Numpad 0 to get the camera's view.
Press Alt+A to preview the animation. Press Esc when you are done watching it.
Save the file with a unique name.
Tracking is very similar to parenting. Select the camera, then select what you want to track. Press Ctrl+T and select Track to Constraint, and the camera will follow the object you want to track.