I've described how I did it in other posts. But basically at 50yo and no boat or mechanical or electrical
experience I got a job at a reputable largish boatyard (50+ people) and they trained me to be an electrician and all around tech. I got parts
for low prices, had access to all the equipment
to work on my boat off hours, had experts to ask questions of, etc. It was perfect for me. I gave back by working hard, learning fast, being easy to work with, customer and business focused, and eager. They hired me because they thought I would learn and give them an honest days work with happy customers. I made a lot of mistakes
and they let me stay. They asked me to return after 4 years cruising so I guess it worked out for them as well as for me.
It is hard work. I started out at $18/hour and it isn't a lot more than than now. Guys out on their own will charge $50 to $80/hr but they better be experienced and good. You can't do that on your own to start without being very good. You'll get exposed and work gets out fast. Being a good car mechanic is not good enough for example.
It is possible as boatyard are always short of reliable eager trainees. You have to accept doing your share of sweeping floors and working on holding tanks
on boats. Then your learn more and more and do the funner stuff.
You will have to buy your basic tool kit though and that can be very expensive. It depends on how you start. You may be able to build up. They won't put you on rebuilding a motor
to start and probably not for a couple of years so you have to understand and accept the learning and experience process. If you can't do that, move on to something else.