I can give you a backwards perspective on this subject, as I will turn 84 soon. My story may make a good data point for your thoughts.
A lifelong sailor, I sold my Ranger 33 sloop about 2015 (age 74) and searched for a slow cruiser ("Trawler"), knowing what my wife and I wanted: Not too large, for easy handling and lower maintenance and running costs. A walkaround deck with good railings or a bulwark for safety. Sturdy construction. Good condition, especially mechanically. I wrote an article for Chesapeake Bay Magazine on the subject and it is in their archives:
Trawler Treason | Chesapeake Bay Magazine
We bought our Grand Banks 32 in Delray Beach FL in 2017 and brought her up the ICW to Kent Island MD in several legs over the next year. That went beautifully and I turned 77, still doing fine with the boat. We cruised our home waters of Chesapeake Bay and had a splendid time.
Then COVID hit us with mild cases (we're vaxxed) in early 2022. That summer both of us came down with "Long COVID" that sapped our energy and affected our ability to reason quickly. Combined with all the other pandemic world effects, we could not make our planned trip to Canada. By the time that settled out, I was 81 and not feeling up to making the trip up the New Jersey coast, through New York and up to the Great Lakes because my endurance was lower, my thinking slower and I would be responsible for the safety of my wife as well as myself. I have made that coastal trip four times as well as many other long cruises and realized that the window had closed.
Now, even local Chesapeake cruising is more difficult and tinkering and crawling into the bilge to work on the boat can be hard, so I am doing less DIY and more check writing. It looks like another couple of years will be about all we will be able to use SNOWBIRD. I stopped doing sailboat reviews for SAIL Magazine this year because climbing aboard from a dinghy while underway and scampering around an open deck were just too much, physically. I had stopped racing our Flying Scot at about age 79.
The point of this monologue is this: Get the boat and get going now, considering how you will run, dock, anchor and repair it. Think about what happens when your aging rate accelerates, as it surely will. In my experience, that starts around age 80 and once it does, exercise, diet and all the other well-meaning health advice have much less effect on your thinking and mobility than they did in your 70s.
I've had a great run of boating since the mid 1950s and it has enhanced my life and shown me the world. It's hard to see all that end but it was bound to happen. And as the Monty Python skit says, "I'm not dead yet!" I could still charter a houseboat on a river somewhere...
-- Tom Dove