The big issue regarding documentation is whether the boat has been documented by the prior owner. If the boat IS documented, transferring the documentation to your name is not a big issue, can you can have a professional do it for $2-300, or I guess you can do it yourself..
If the boat is not presently documented, the process is more difficult, and even most difficult if the boat was built outside theUSA or if the builder is out of business. Here's a prior thread..
PS= remember that visiting Canada is leaving the USA.