Non-Eu vessels may temporarily be brought into and used for private purposes in the EU, without customs duties or Value Added Tax (VAT) needing to be paid.
The boats concerned, have to be placed under the “Temporary Admission procedure” (TA) with customs. The period of use in the EU is limited in time (normally for one and a half years). When the times is up the boat has to leave (“discharged”) otherwise customs duty and VAT become due.