Re: What do I need to be legal?
Some states require you to register the boat, even if it is USCG documented. Some do not. Some will charge a sales tax on your boat purchase. Some will not. Some will also charge you a "personal property" tax each year on the value of the boat and--you guessed it--some will not.
Do a google search for "vessel registration virginia". I'm sure you'll find that the state of Virginia has a website with all of the information you need.