I am retired so I can give you an opinion based upon experience, for what it's worth.
Honestly, I think the boat you own in retirement should be one that you can pay cash for without hurting your financial security. You will spend 10% of the boat's purchase price annually for fuel/maintenance/berthing/insurance and "stuff". That doesn't include unforeseen repairs and replacement of systems and upgrades to the boat itself to make it "your boat", assuming you are buying an older boat and not a new one. Your first few years of ownership will be very expensive doing all the above. If you are retired with limited assets and a fixed income, you don't want a boat payment on top of that. When you are done with the boat, plan on getting 50% of what you paid for it. People occasionally do better but plan for the worst and hope for the best.
Bryant,
Good points. There is CERTAINLY a strong argument to not have any sort of undo financial burden in owning a boat.
However, your 10% for maintenance needs to have more details..... and that depends on a LOT. If one gets an old clunker in disrepair, perhaps, but a boat in good condition should be a fraction of the 10%. I could strongly argue that the "maintenance" only part.... scheduled and unscheduled is probably more like 1 or 2%, especially for the single engine, do it yourself folks which is probably most of us.
Berthing or slip rental is a whole nuther story.... some spend a fortune and some spend zero. I prefer zero and like it.
Insurance is in the 1 to 2% of hull value range, at least what I'm familiar with, but will let the insurance guys comment on that one.
As for the first year of "fix up" items. I could argue that one put that into the "acquisition" column, but there's always a few "new" things we add to boats over the years, but pretty much a choice.
I don't think there's any magic number of boat ownership, like a percent of net worth or income. A full time live aboard with a Fleming and no house or car might spend a large part of their net worth, where a guy who buys his boat with pocket change and uses the rest for his 3 homes, Gulfstream and mistresses might spend a lot less. That's just a choice we make.
One thing we retirees need to pay attention to, is inflation. Especially if we rely on mostly fixed income. I could argue that the basic cost of living will double in the next 10 years (after our recession) and most of the boat costs will, too. Hopefully, that inflation rate will soften after we get our country in better order and reduce our debts, but who knows.
Boating is still better that a LOT of other activities!