www.rya.org.uk will list them, and a search of this forum will show you very recent post as well - but to recapp as a welcome to the forum gesture................
passports for all
certificate of insurance (not mandatory but may be required by a marina to berth)
ships registration papers - original - part 1 or 3 (SSR)
ICC if going inland (believed to be beyond tidal waters)
original purchase papers showing vat paid on craft (if applicable - ie not exempt in some way by age)
if radio onboard - ships radio licence and your operators licence
have a good trip -
ps wait 2 hours after reading this response - if I have missed something someone else will point it out!!!!!
Duncan is pretty close. Look <A target="_blank" HREF=http://www.rya.org.uk/Cruising/faqs.asp?faqCategory=1020425>here</A> for the RYA's advice.
Note that it is not actually a requirement to have proof of VAT-paid status. It seems that monitoring this is a task taken upon themselves by France. There have been some experiences posted here in which UK sailors were fined for not being able to demonstrate VAT status. Just what "demonstrate" means is not clear. Few owners of boats bought secondhand will have originals of documents showing VAT-paid status, since this rule has been applied retrospectively. The builder of my boat no longer exists, so I cannot obtain "original" duplicates. The photocopies that I have show the VAT registration number but I don't know if French authorities will accept them.
The only reason why I can think of the French taking it upon themselves to check VAT status is if the boat is suspected of being a charter. French charter boats have not only to be VAT paid but must also comply with strict safety provisions. If a UK boat not subject to the same costly provisions were to charter in French waters there would be an unfair trading advantage.
There seem to have been many examples reported here in the past year of British-flagged boats being boarded, either in port or at sea, by French customs(?) officers. Main emphasis of the consequent inspection seems to have been registration documents and VAT-paid status. Some instant fines have been reported.