My '94 C270 is documented and has been since
new. Coasties use some kind of formula of their own that comes up with some kind of displacement figure. I was a little surprised when I first looked at it also because I didn't think a 27 could be documented. Call the documentation center, they are pretty good about returning them.Here the main "advantage" is that you don't need to register with the state & therefore maintain numbers & sticker on the bow. Also free to renew as opposed to small annual state fee. Not much really, some lenders require documentation because they think it better proof of a clear title with no liens against the boat. Not sure how true that is, could depend on the state or it's just easier for the lender to deal with only the feds and not each state DMV or whatever.