Documented Vessel issues
Technically, if a vessel travels to a foreign port of call, it *should* be documented AND have an FCC radio station license.
The benefit of documentation for being soley on US waters has already been stated (banks prefer it, it looks official, it's esier to trace history of sales, prior owners, etc.).
The major benefit of a documented vessel is mostly for traveling overseas in that the boat is actually considered United States 'soil' or an entity of the U.S. Whether other countries observe that rule is a toss up. Foreign soldiers with machine guns boarding your boat are not keen on any discussions/arguments about U.S. rules and regs......but the vessel *should* be treated similarly as if it was U.S. embassy property. BUT, machine guns and orders usually outweigh that agreement every time.
Documentation does seem to expedite port clearance and inter-country travel as the vessel has official USCG paper work and the official number that they can look up if so inclined. Trying to look up a state registered vessel is probably next to impossible in some countries, hence the hassle. Plus, those state reg. stickers can be peeled off and new ones put on very easily.....i.e. theft then sale in a foriegn country.
Some states do require registration stickers (revenue enhancement), but no registration numbers. Check with your individual state laws as they differ from state to state. If a boat is USCG documented, the official numbers MUST be permantly affixed to a structural or major component of the vessel and be a minimum of 3" high. I've seen it carved into frames, welded onto a bulkhead, even one gent had the patience to actually drill out the number outlines into a plate and then weld it to a frame - very impressive (and time consuming, but very nice looking). Also, it must start with "No." following with the offical numbers such as "No. 123456". As stated, be minimum of three inches high and permantly affixed to the boat some how.....stickers are a no-no. Also, the vessel's name and hailing port must be on the stern and if engaged in activities such as commercial fishing, coastwise trade, etc., the name must be on the port and stbd bow as well.
If there are no changes to the USCG documentation info (besides owner's address), there is no annual renewal fee. So you are done with the USCG $$$ wise unless you need to change info such as name, drop/add an owner, etc.
See USCG NVDC website...it has plenty of FAQs on it:
http://www.uscg.mil/hq/g-m/vdoc/nvdc.htm
Does that help any?
John M.