As I understand it, the registration applies to
-Any boat with a motor (gas or electric),
-Any boat 14' or longer, OR
-Any boat with a title
If the boat came with an active NC title/registration, converting to your name is not hard, just a matter of a check and a form. If the existing NC title/registration is not current the process is slightly more difficult. If no existing title/registration, the process can be very difficult - to the point where I have been told to flat out avoid buying a previously unregistered/untitled boat, especially from out-of-state where registration is not required (looking at you, South Carolina).