This all sounds nice, but you seem to mistake preserving the culture, which can be done quite economically, with preserving the actual ships, which are made out of biodegradable materials and are extraordinarily expensive to maintain. At a certain point priorities need to be set, and that may mean you can't afford to keep pouring money down that "hole in the water."
European economies, including Portugal, are learning this the hard way right now. The severe austerity measures have been a disaster, but some changes are going to have to be made to bring your spending down to a sustainable level, and with so many truly critical things to spend money on, I am not sure that maintaining these old ships can or should continue at the same level that it has in your countries.
I am a naive Yankee outsider, so take my comments with the appropriate grain of salt.
Yes, it is all a question of priorities, mainly to the people. The money needed to preserve 3 or four boats is quite insignificant even in the budget of a country like Portugal.
Around here people are quite pissed about the huge money that was spent on two new modern attack submarines (more than enough to take care of all old boats for a huge amount of years).
If any emblematic boat needed maintenance and the state could not provide it it would only be necessary to open a raising fund and the people would get the money because it is important to them and to us as a culture.
It would not be the first time. Some years ago a huge amount of money was raised that way to recover the XIX century Frigate Fernando e Gloria (badly damaged after a fire), the last ship from the "Carreira da India", the last of many hundreds on the last 500 years.
The boat is today a museum and a very good one.