Ahh, just saw your second post. What you''re proposing is a stateless vessel. This will be a problem for you, eventually. Even if you don''t insure and don''t cruise for extended periods inside the U.S., you will some day stay long enough in another country or island nation which has enough of a regulatory presence to wonder why your vessel shouldn''t be registered (and taxed) in their country, since you haven''t done it anywhere else. There are also some protections you would enjoy from the U.S. govt. when in foreign waters, assuming U.S. documentation. But I think the primary benefit is that you instantly ''become'' one nation''s property and therefore be honored as such by all other nations.
E.g. here in the EU I think you''d quickly be challenged if ''stateless'', potentially be liable for VAT (a robust 17.5% here in the UK) and all the waterway and boating-related regulatory obligations forced on EU citizens would be applied to you as a result. These do not apply to us because, by reciprocal treaty agreement, we are considered to be in compliance with EU rules if we comply with our home country''s regulations. You would fall outside this protection when, some day, some bored or industrious local official decided your paperwork was incomplete. (We''ve now reached the subjective part of this discussion...but I would hate to cruise with that hanging over my head).