Here is the reference to the code section - http://leg1.state.va.us/000/cod/58.1-3511.HTM - § 58.1-3511. Situs for assessment; nonresident exception; refund of tax paid to city or county; apportioned assessment.
Any person domiciled in another state, whose motor vehicle is principally garaged or parked in this Commonwealth during the tax year, shall not be subject to a personal property tax on such vehicle upon a showing of sufficient evidence that such person has paid a personal property tax on the vehicle in the state in which he is domiciled.
See also Attorney General Opinions in connection to Apportioned Assessment -
and Rulings of the Tax Commissioner in similar matter - http://www.policylibrary.tax.virginia.gov/OTP/policy.nsf/df8f027f3fea473a8525697a00730e76/b5a81bf77e30d97c85256a01006d7a8c?OpenDocument
Even if you are a non-resident, you are liable for the boat personal property tax if your boat is garaged or parked in Virginia...
Also boats are not eligible for the Commonwealth Car Tax Relief program.
The issue is that determination is made on the locality level - not on the state level - and because they are short on revenue - all tax authorities are very aggressive on all mean of tax collection...
I am not in the position to determine your liability. It would depends on the time period the boat remains in Virginia (and in the US) and owner's status in the US.
The fact of the boat was subject to VAT under EU law - has no affect on the Virginia situs for the assessment determination.
I suggest having a local tax person to represent you with the locality. If the comprehensive person speak on your behalf - they might act differently.