Your passport is irelevant. It’s where you intend to keep the
boat that’s important. Also is it Spanish registered.
What’s important is the document trail. You need originals not copies of all bills of
sale plus the original dealer sales invoice showing vat paid.
You need to ensure no outstanding loans are registered against the vessel. ( by requesting the
registration transcript ) and further more a undertaking from the seller that the vessel is his to sell and free from all encumbrances. Use something like a standard
marine bill of
sale ( U.K. MCA is a good one ) and have it witnessed by a notary or lawyer ( this depends on country ) get two bills of sale both witnessed
Then depending on where you intend to register , you’ll need to deflag from the existing register and reflag into the new one.