To the OP, thank you for starting this thread.
I have been meaning to start a thread on this topic for a few weeks but have been too busy.
Part of the problem with this question is the meaning of "maintenance."
Does maintenance mean all expenses to maintain the boat including insurance and does it include OPERATING expenses? I dont' think it should and these should be separate line items in the budget.
In Leonard's "The Voyager's Handbook" she uses the 10% number but ONLY applicable to fixing things on the boat. Not insurance, not operating expenses, not docking fees, etc. Just fixing Da Boat.
On their website, there is a PDF called Cost of Cruising that looks to be pretty close to what is in the latest book, Articles
The smallest, simplest boats take, on average, somewhere around $1,000 per year to keep them sailing safely.At the other extreme, brokers selling boats over 50 feet say you will need to budget an amount equal to annual depreciation – on average about 10 percent of the cost of the boat per year over the course of a ten-year voyage – to maintain the boat’s resale value. While many cruisers we know with complicated boats between 50- and 60-feet scoffed at that in their first few years when their boats were brand new or newly refit, most of them came around to that point of view in the fifth or sixth year after a major overhaul. Our three crews spend between 25 and 30 percent of their total budgets on boat-related expenses.
Given that Leonard and her partner have sailed around the world a couple of times, I have to give great weight to their experience but their numbers seem high to me. 10% or even higher depending on docking expenses, for all operating expenses minus financing makes sense to me.
There are discussions on the same topic on the Cruising Forum where there are people with spreadsheets of cruising expenses on a variety of boats. I don't think any of them are near 10% per year JUST TO MAINTAIN the boat. People on TF and CF who talk about maintenance costs seem to be 1-3% of the boat value.
My dad and I had a long chat about his maintenance costs for the 33 foot sail boat he owned. Best we could tell, he spent 2-3% a year but he did most of the maintenance work himself. However, we think he got ripped off on a transmission repair, and if that had been done correctly, would have gotten his expenses under 2%. We also think these are high numbers AND the numbers include damage from a lightning strike. However, he did not replace his sails and if he had kept the boat another 4-5 years, he almost certainly would have needed new sails. Having said that, the cost of the sails would have only added another couple percentage points over a 10 year period and would not be close to 10%.
By the way the previously mentioned website is a wealth of GREAT information as is her book. HIGHLY recommended.