The plans are to retire and cruise. I'm an able bodied captain of a 40 foot trawler that has plans to cruise the coast, maybe even the great loop. My previous mate jumped ship. How do you find a seafaring mate with benefits in a short period of time? Where do you look?
If all you want are the "benefits" then perhaps less expensive just paying for them in each port.
If you're after a seafaring mate, then I'd suggest making some friends without benefits first and taking it from there.
Retired, cruising on a yacht (yes to many people the 40' trawler is a yacht) will attract a lot of people, some good, some bad. Some with pure motives, many with bad ones. Be honest in what you're looking for and hope to find someone who'll be honest in return. That's where online dating sites do help a bit as you have to put what you're looking for in writing. I'd suggest doing that anyway. Are you looking for happily ever after or just fun on a boat? A partner in life or just a hot and willing body?
Now I'm not saying any of these are wrong. We've met some extremely happy trophy wives and their husbands. They each got exactly what they wanted.
Then last it's what is the agreement if it doesn't work. When I was younger, my neighbors had a friend and his girlfriend or traveling companion visiting and the plan was for all of us to go out on my boat. Well, the friend was a jerk and had left the day before leaving the girl he'd brought with him from Minnesota to NC behind. Fortunately, my friends were nice and allowed her to stay for a few days while she figured out what to do.
You're looking for the "living together" arrangement with little or no dating before hand. Odds are terribly low that it will work out. But if it does it's worth it.
Who knows. My wife and I fell madly in love the night we met.