We had a very successful charter business in the Caribbean until the C-19 imposed travel restrictions world wide. Obviously, this season died in February and we cannot foresee any business next season as most of our prospective customers will probably take a pretty big financial hit because of this pandemic.
I would advise you scrap any plans for chartering until at least a year from now, or when a vaccine is available to all, unless you are looking to charter to the very rich (minimum $50,000.00+ a day), who will still have disposable income as soon as the borders open up again.
When and if you actually get into the business, remember that the food is by far the biggest selling point and good old fashioned "home cooked" meals just won't do. Unless your partner is a professional cook, be prepared to hire one, though a chef would be better, for at least the first season to get your reputation going. That's going to take a big bite out of your income.
Assuming you would like to be running your vessel as a couple, if your partner is a capable chef, remind her that she will also be the maid and house keeper. Making beds, vacuuming daily and making sure all windows and mirrors are spotless is a necessity. You, on the other hand will be the helmsman of the yacht, the ferry driver of the dinghy, the engineer and outside maid, cleaning and polishing every bit as much as the inside maid, every day.
No matter how unpleasant your guests are (it does happen from time to time), even though you are on your own boat, in your own home, you just have to smile and bear it.
But by far the most important thing you will have to throw out the window, if you are chartering, is the idea that you can sit in some comfortable bay, harbor or marina waiting out bad weather. There are no weather windows on a charter boat!!! You have a schedule to keep, no ands, ifs or buts; when you've got to go, you've got to go. Now and then, or even more often, depending what the weather is like where you charter, you are going to be beating the hell out of your boat. Therefore, more things are going to break and maintenance costs will rise. If you can do this work yourself, then you may actually make a decent living chartering. If not, and you have to hire professionals, you probably won't.
There's nothing better than getting paid to do what you love to do, but it isn't all all roses and sunshine. With the internet today, a hard earned reputation can be destroyed by just one unhappy charter guest. I'm not trying to turn you off, but only trying to give you a realistic picture of what chartering one's own boat is like.
Good luck.