A non EU vessel may stay in the EU for up to 18 months without having to pay the VAT. Leave the EU, even for a day, get the proof, and your 18 months starts again. An alternative we looked at was to 'seal' the boat; have the Aduanas issue a piece of paper that she was 'in bond' and not in use. You then get them to issue a second document to unseal the vessel. While under seal (either up on the hard
, or in the water), the boat may not be operated and the 18-month clock is stopped. We were dealing with the Spanish and the bureaucracy & language issues involved were enough that we didn't pursue sealing the boat. Getting out every 18 months is the best option if you are moving about, but I'm hearing some countries are getting sticky about some of these non-EU destinations.