Which flag?

We won’t be looking to buy until at least a year from now, so this was just some preliminary thoughts around flags and the implications for maintenance and safety standards ?

As we’ve ended up covering VAT and Brexit anyway, it’s certainly in our minds. However for the majority of ownership we’d be keeping a boat somewhere and visiting to sail for max 3 weeks at any one time, which shouldn’t be an issue. For our sabbatical, we’d have a max of 8 months cruising time and prefer the eastern Med/Adriatic etc so would be flexible and plan as necessary to comply with regs then, moving between Croatia (if we end up treated as all other non-EU nationals then likely to be max 90/180 days but NOT Schengen), Greece (Schengen), and Turkey.
Croatia hit their targets for Schengen compliance this year, they're expecting to sign up in 2020/2021
 
Croatia hit their targets for Schengen compliance this year, they're expecting to sign up in 2020/2021

I know... we’re very conscious that everything is a moveable feast right now for Brexit and other reasons. But for our one-summer sabbatical, when it happens, we’re very flexible and have a number of options, so the question was just about flagging and registration, not immigration ?. Longer term ownership wouldn’t be an issue as long as we have something similar to Schengen apply to us as we’d be visiting for 1-3 weeks a few times each summer.
 
Maybe I'm missing something but why do people refer to 90 days in Schengen area? Surely it's 90 days in any EU State whether Schengen or not?

For non-EU citizens (and who knows how Brits will be considered post-Brexit), most tourism in the Schengen zone (which currently includes most, but not all, of the EU and additionally some other countries) is on a Schengen Visa which gives free movement/time in the zone for 90 days total (across any number of in-zone countries) in ANY 180 day period (ie a rolling period). So if we take 6 months off, and by then are considered in the same way Aussies, Americans are etc, we could only spend half of our time off in the Schengen-zone. Hence almost hoping Croatia doesn’t join Schengen too soon as it’s make life easier in those circumstances, and planning on utilising time in Montenegro, Albania and Turkey as they wouldn’t count toward the 90 day limit

There are other visas but many require study or work which wouldn’t apply to us personally
 
I'll try in the liveaboard forum too, but a further quick (?!) question - how on earth does one buy a boat and have somewhere to put it? i.e. many marinas have waiting lists, we could join but no idea how long a purchase would take (as we could buy the first boat we see or the tenth...months later) and presumably unless we'd pay for a berth and keep it empty we'd get passed over for the next person on the list.

If we did have somewhere lined up, it could be days of sailing from where the boat is and we might not be available immediately to move it there or it might be bad weather etc...

So; do most boats have some leeway on staying on their current mooring/cradle etc that people negotiate with the seller +/- a combination of monthly/weekly/daily berthing until a desired longer term berth becomes available? But those boats for sale that are coming out of charter must need to be moved by the time the new boats arrive to replenish the fleet etc. My mind boggles at how this all lines up!
 
Cheapest option is usually to have the boat hauled into a yard local to where it's purchased if will be some time before being moved and no berth available. Be aware that not all yards allow living aboard and some will also not allow owners to carry out their own work. Some marinas will allow a boat to remain in a berth after change of ownership but, it depends on their terms and whether a waiting list.
 
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