I live on a sailboat during the winter. I grew up on the boat... In Mexico for 12 years and then south. The boat is in Panama now.
It is an interesting life. Or a terrible life. It really depends on you.
As far as frugal... It can be, sort of. A boat can cost new as much as a house, and they depreciate almost as fast as they can sink. Next, have you ever been to a marine store? If you thought the Apple store was overpriced! HA!! You haven't seen nothing yet.
On the other hand, there is the flip side. Boats aren't worth anything when people are done. Lots of people just walk away. Usually somewhere in Central America or the South Pacific. They need work (difficult, hard work) that you'll have to do. Since even if you can find someone willing and capable, the hours needed to do almost anything is crazy high, and therefore expensive. We always celebrated if a small project was completed in one day. It meant we didn't have to live overnight with things tore apart. You expand as a person, learning to maintain every system on a boat is an amazing resource. After working in a cramped, hot, loud engine room... Working on a car is easy!
I know of a boat in Panama that has sold 3 times. First for 5k. Then 2k. And last year for 1k. This boat was 75k new. In 1975.....
If your living in a marina... Well I don't know. We've never been in a marine more than a week. Last time was 1997. Those people don't last long. Marinas are expensive. (an exception is if your working and a marina + boat is cheaper than an apartment).
Once you leave the normal areas, California, Mexico, Florida, most of the Caribbean.. it is lonely. We get a few boats a year through Northern Panama. It's a notable event to see someone sail into the bay. So if you like friends, this isn't probably for you. Plans never line up, your staying their going, your going their staying... When I was a kid I learned to make friends fast. You couldn't exclude anyone. They might be the only kid(s) you'll meet for a month or more.
People that go cruising all go for a reason. Some to avoid the law (more common than you'd think). Many are single males, wonderers. Many are out there with wives who don't want to be there. Many families are trying to avoid American culture and its influence on their kids. And many are retired and this is their Florida.
Living on a boat is best done full time, year around. It is a major hassle and lots of potential problems to leave the boat. Theft, storms, mechanical failures... We have been lucky, while we've been gone our boat has been broken into at least 10 times. It has almost sunk, twice. It has drug out the bay due to someone moving our anchor. It sat in the mud for a month because someone stole our chain. It has leaked and ruined woodwork. In all that (and more) it's still here. We take everything off the boat, nothing of value is left. So although it's been broken into, we haven't lost anything. We don't pay someone to watch it. Since when we have... It was more of the same. Panama has been better than California and Mexico. I don't know about Florida, since we've never been.
After all that. For the right people. Sailing is amazing. You can do it cheaply and it gets you places that otherwise you'd never go.
Two things to take away.
1. You must learn to fix everything.
2. Leaving the boat is the worst thing you can do.
Sorry for any typos - I'm typing on my phone.