USCG registration is great once you're registered for the first time. I'm not sure how involved the first time registration is because my broker took care of it when I bought my boat. But the renewal is as easy as it gets. CG sends you a letter every year. You sign it and return it to them with no fee! Couldn't be easier. In Massachusetts you don't have to register with state. (Still need to deal with the town for purposes of excise taxes and of course you have pay state sales tax when you bring the boat into Mass. if you bought it out of state.
I have a follow up question to this thread. What about the tender. I have an inflatable dinghy with a 6hp. I've been told that the tender is part of the documented vessel. I have never heard this from an authoritative source. I've had two different harbor masters on Cape Cod stop my while in my dinghy ask me where my Massachusetts registration #s are. I've told them that the dinghy is a tender to my CG registered sloop and that I didn't need Mass. registration for my tender. Both harbor masters just said OK and let me go. So I assume I'm OK would like to know in anyone knows anything about this. (Yes, I can't believe the harbor master's don't have anything better to do than hassle someone in a 6hp dinghy about registrations.