There are always lots of barneys going on about what you need, the legislation under which it is demanded and whether fines are properly levied. All these
regulations are subject to spot checks rather than blanket coverage, and the precise interpretation of the law (which can be very complicated) will be down to the customs officer you meet on the day. We take the view that they are officialdom, we're visitors in their country, usually we don't speak the language and they carry
guns so we produce what they ask without challenging the precise legislative underpinning. (We've refused once while being shouted at during an anchorage mass-eviction by a snotty Italian cop in Sardinia.)
Incidentally, do NOT assume that you will not be checked at
anchor: you frequently are by customs people in
France,
Spain and
Italy, as well as in
marinas.
(i) VAT: you may well get asked for proof at main borders close to a non-EU country. We never have been (we sail an obviously pre-VAT
boat but would have to show proof of the vessel having been in the EU on relevant date, which we do carry on board.) VAT is levied by your country of arrival in the EU and VAT rates vary both between countries and over time. (UK VAT goes up to 20% in Jan!)
(ii)
Registration - subject of a huge row on another forum but you will be required to produce
registration papers by
marinas and customs almost all over the EU. Note that there are stories of fines for vessels who are carrying copies of their registration docs rather than the original.
(iii)
insurance: customs uninterested but marinas will often (especially in
Spain and Portugal) ask for this and in some countries, eg
Italy it is a
legal requirement that your cert be translated into their language. Many
insurance companies here provide these translations for free.
(iv) Cert of Competency: we have never been asked for one (though we carry two ICCs in case). Some US friends of ours were requested to produce one by Italian customs. They don't have one, and were told that they could be fined up to EU3000 for the lack. But the police couldn't be faffed, and obviously reckoned that sailing a 47'
boat from
California to Elba counted as competence. But it is the law, I believe, that any boat sailing in Italian waters must be skippered by someone who can produce documentary evidence of competence. They are as entitled to demand this as they can expect you to show proof of your ability to drive a car, even if your country does not require a driving
license. So you need something that they will recognise as in date and validated by an acknowledged body. (Doesn't
ASA do anything to help with this?)
(v) passports etc - your visa requirements may be much shorter than your VAT holiday. OTOH you may find great difficulty in getting your passport stamped when you enter an EU country by yacht, especially if you have come from another EU country.
I should emphasise that this view is based on practical
experience not from a catalogue of
legal references or a detailed knowledge of international maritime law. Depends whether you want to argue with cops or go sailing!