Trying to answer the original question, it does depend on where you end up each season, but also on whether you want to visit the boat over the winter - eg use it as your 'holiday flat' for weekends etc. If you were to do that, you'd want to be somewhere interesting, and you'd probably want to be afloat. So - for our 12m boat currently in Rome,for six months,that's 2,400 euros including elec.
The inclusion of electricity is key if you are spending any time aboard, as it will quickly mount up if you pay marina prices for fridge etc.
By contrast, if you go somewhere, haul out
and come back in 10 months, then you can get your prices down to about 1000 euros for six - nine months, but there are two things to consider. Firstly is security
, both in terms of boat stands (as far I've ever seen universally provided by the yard in Europe) and of the yard itself.
Secondly is whether you are allowed to or wish to either sleep aboard or work on the boat. At the very least you will need to have the boat anti-fouied every year, so in looking at yards you need to assess whether you can do this work, while being aboard for a few days, or will have to pay them, plus any hotel fees
. This can make a huge difference to an apparently good value on-the-hard deal.
You say you are meandering west from Turkey
to Gib, and not using the canals, so you may not wish to go north towards southern France
etc. (Though we found the Riviera an excellent and good value cruising ground) In that case, the debate about Port Napoleon and Navy Service
is irrelevant because you will be interested in Malta
, southern Italy
, Balearics, maybe Tunisia
. In any case, the situation will evolve over the next few years and new harbours will be offer facilities.
In summary, if you allowed 2500 euros in today's prices for out of water storage
plus the minimum works, it should be a generous estimate.