That's an interesting though perhaps also a 'piece of string' sort of question; it did get me looking back at our own expenditure records for the last five years during which we've been on passage/cruising for 6 or 7 months, then winter lay-up ashore, covering a trip from Wales to Greece via the Western Isles of Scotland.

Bear in mind we're only small (27 foot and probably Ł11/12k in value) and definitely low-tech (If its not fitted it can't break) but our annual maintenance cost has been amazingly consistent (+/- 6%) at around Ł1200 every year.

This is calculated exclusisive of mooring/lay-up charges and annual insurance premium, but includes all fuel, oil and replacement parts, for the proper maintainence & repair of the vessel - I consider the boat to be in equal if not better order now than she was the day we set off.

There's not a lot of labour costs as I've done virtually all work myself.

As consistent as the overall expenditure has been the cost breakdown itself identifying one Ł500ish renewal expense each year (mainsail, electronics, cruising chute, fridge) and the rest in fuel, oil and bits & pieces.

Our experience seems to bear out OliveOyl's estimate of 10%.