Yachting and Boating World forums: Having a ship in an other EU-country than your own.

A lot has been written about the need to register your boat in Spain after having spend more than half a year in that country. I am living in Spain now for almost twelve years, am an official resident with the necessary papers and am considering buying a ship, but it is unlikely that I manage to find the ship I want in Spain. That means I have to import it into Spain and fear that I have to register it there. To do so would require a kind of survey to establish the "floatability" unless it would have a "CE-mark". One of the ships I am looking at is at the moment registered in Portugal and has the official papers of that country for coastal cruising. The spanish authorities indicated that they would not accept this and would require their own survey. So much for the european unity!! All this is mainly, in my eyes unnecessary, bureaucracy, but there is also an emotional angle to it all. The fact that the ship would be registered in Spain, means that I can not fly my own national flag (in this case the dutch flag).
I wonder how the situation is in other countries. From these forums it would seem that quite a lot of britishers have their ship in Normandy and Brittany. Does the french gouverment require that these ships are officially registered in France?
I know that many belgians have their boats in the southern part of the Netherlands. I don't recall that the dutch gouverment requires them to register their boats in that country. As a matter of fact their is no registration required in the Netherlands.
I wonder if it is acceptable under the EU-rules that a gouverment of an EU-country obliges a citizen of an other EU-country to register his ship in that country if it has been there for more than a certain period. Can they oblige me to fly a flag which I don't want to fly, because I live in that country, but do not have its nationality.
From a foregoing thread initiated by GREHAN, it is evident that at the moment the spanish authorities are checking up on the live-aboards in the marinas in S-Spain and that some seem to be required to pay large fees for all the years they wre obliged, but did not register their ships in Spain. I feel that this problem should be looked into from a more fundamental point: Can the gouverment of a EU-country oblige the citizens of an other EU-country to register their boats in that country.