At what size will insurance allow single hand operation?

I can answer affirmative to all 3 of your questions citing examples. However, it depends on your experience! For example, if you have owned small boats, and then purchase a 60 footer, insurance will most likely require you to hire a captain until the captain "signs off" that you are qualified to skipper your own vessel. If you are moving up from a 50 footer to a 60 footer, not necessarily so.

Depends on where you are and your experience.

Typically 70/75 is where most will start requiring a full time captain but there will be exceptions. The question is more like will you be willing to spend all the time required to clean, repair etc. yes you can hire day worker for a number of jobs but when an impeller goes on the generator in the middle of a 90 degree night or an air con pump goes kaboom in the middle of lunch...

It depends on the boat and on your personal standards. I d say one to two hours a day

Sail or Motor?
Really the answer is the same. A lot. An owner couple will never have nothing to do on a 70, 60, 50 and even 40 footer. Not that everything to do is mission critical but there will always be something to do. That is just the nature of it. I don't say this as a negative at all. There is so much to learn and gain self satisfaction in this process. It is taking me years to get to know this and I now expect to be doing something for the boats at all times if I so choose. Balancing self labor and hired labor is how I prefer to do it. For instance, I used to wash my boat. Now a hired crew does that. I can't tell you how lovely it is to arrive to a clean boat, not to mention the ease of keeping her clean when done on a regular basis. I could go on and on. Yesterday I was in the engine room (I clean that as I want to be hands on down there to keep tabs on everything) I noted a damp area next to a stringer, surface water. There was a small drip from above. Turns out on of the cockpit scuppers was leaking around the fitting. I took it out to discover it was simply seated on a flange with a black rubberish gasket that had deteriorated. No biggie, I was able to fair it with epoxy, sand it, and bed the scupper with 3M 4200 fast cure and I am now leak free. Well, leak free for now. You see, there will be another leak somewhere.

It's also the timing of the labor. While you may not do as much as professional captains like Pascal would do, you still face the boat being covered wish salt spray after a long run outside. You're tired from the long day already and would prefer to go straight to a restaurant, but first you need to wash all the salt off and chamois the boat dry. Oh, and it's already 8:30 PM. Sorry it took 2 hours and the restaurant closed before you made it.

As Judy said, people are doing all three things the OP indicated. However, not my idea of pleasure boating to spend hours just on basic upkeep. There are people who love taking care of their boat more than the boating itself.

An owner managing a 60' themselves. Pressing the upper limits.

A couple on an 80 footer, depends on the couple. If they're both fully committed and capable of everything including captaining then ok, but otherwise not. The couple must both be active, involved crew themselves.

Family on the 90 footer, works until the kids have better things to do and you can't go boating. The reality is most people have jobs and other activities and depending on anyone to always be with you is not wise.

Both good points. Now incapacitation is always a risk and that's where my comment on both being fully trained and committed and capable comes in. One can single had an 80' if the other is incapacitated and safely get it to shore. But that one must be fully capable.

50 60 70 or 80 feet makes little difference when it comes to handling or even single handling Regardless of size the captain needs to put the boat in a position where lines can be passed ashore. The size doesn’t make much of a difference. Whether 60 or 90, one is not going to manually wrestle the boat in position

What is far more critical to ease of handling is the boat layout. A boat with a pilot house on the main deck and doors on each side is probably the easiest to single or short hand as you are within a few steps of your spring lines. On the other hand a flybridge boat without controls in the cockpit will be the most difficult regardless of size

same with walk around decks. I d rather single hand the 84 MY I used to run than 60 footer with extended deckhouse and no side deck.

As to incapacitation, yes both husband and wife need to be able to take over if needed and at least get the boat out here help can be obtained. It s one thing for a spouse to be able to dock the boat while you re standing a few feet away. Now if you re dying on the pilot house floor ... the psychological pressures will be tremendous. My instructions to my wife are clear: call for help and get the boat outside whatever marina or harbor, and drop the hook.

but again, it s not about size it’s about layout.

It all depends on how they intend to use it. If regularly having 6 guests aboard, then go bigger, if replacing a 8000 sq ft home, perhaps bigger. Also, crossing larger bodies of water but then definitely need to add crew. Either way if owner operator couple very dependent on both and either one must be capable of getting safely home without the other.

While we normally have crew on anything more than our 44', my wife and I are both trained equally.

Pascal points out what so many miss that running the boat just doesn't change much on size. It's all the other things. We go from 44' to 130' and operating the boat, running it to safety, just isn't much different. It's like a 900 sq ft apartment versus a 9000 sq ft house, living is the same but maintenance is sure much different.

As a relatively new yacht owner (four years), this has been the biggest surprise for me. The amount of time and money it takes to maintain a 20-year old 70 footer, in my case, has been overwhelming at times. Boating is such a wonderful experience but it doesn't come without a price. For me, the boat has brought tremendous joy and satisfaction but it also takes a lot of work. All worth it but better to be prepared going into it than not.

I spent the first 42 years of my life boating on a lake, boats up to 30'. It was simple. As you move larger then you have to weigh the amount of work you're willing to do and the amount of money you're willing to spend paying others. Those both have breaking points and differ for everyone. I'm willing to do far less than many myself but spend more on professionals. Some are willing to spend hours every day on maintaining their boat and enjoy that as much as running it. However, it takes labor, either your own or someone else's.

It also depends on where you use the boat. For instance in the Bahamas pretty much every marina has a couple of guys ready to watch your boat as soon as you dock. Great for an owner operator couple. I use them sometimes so we can take better care of the guests.

same with interior cleaning... we ve never had issues finding a cleaning lady in the Bahamas when short on time to get the boat ready.

There is no doubt that a bigger boat cost more to maintain but it also also easier. I believe Brian has a 70 Johnson; I ran one for 8 years so I m intimately familiar with the engine room and the systems. It takes me half the time to do the same the maintenance tasks on the 116 Lazzara I run now. I no longer bang my head on the ceiling or have to crawl in a corner to reach a genny impeller or squeeze along the front of a hot engine to access a fresh water pump.

bigger boats also have redundant systems so often if something fails like an air con pump, genset, water pump etc you can just switch to the back up. As an owner operator you don’t have to abandon you family on the spot to fix something.

so many factors.

Ferrus:
My wife and I operate a 75 Hatteras MY without any other crew. I've had a number of other boats under 60' and had no problem insuring the 75.

While I enjoy hands on maintenance, I will hire out the task when time does not permit me to accomplish same. I DO NOT enjoy washing the boat, consequently, I hire a crew to wash every week or after use and try to pre-arrange the task when we cruise.

If we will be going a longer distance and need to crank out miles rather than enjoy the voyage, I hire a mate and or captain to assist with the trip.