While the items mentioned above can help determine the costs of upkeep and maintenance
-- on any size boat -- the real determining factor is the standard to which the boat is kept.
It is a sad fact that most of the boats on the used market have been very poorly kept, either mechanically or cosmetically or both. As the economy has tanked, it's my view as well as that of my professional boating
colleagues, including surveyors, that the issue of poor maintenance
has become epidemic.
You can look at 20 boats and see only one, maybe two, which have been decently and professionally maintained.
Even if you as an owner are exceptionally skilled and have the very considerable time needed to maintain a cruising vessel, there are costs which you cannot long evade without impacting on the overall condition of the vessel.
How much does it cost? Maintenance costs vary widely, but on average somewhere between 5% and 10% of the value of the boat per year
to properly maintain a boat is likely to be in the ballpark. Some years will be much less, some much more.