Learning about boating and other marine related activities is not something you can pick up overnight. We used to call guys who go in green and get a Captains License, PAPER CAPTAINS and I don’t even think you can do that without documented sea-time. Just means you have the paper license but would be unreliable in most situations you will inevitably find yourself in as the Captain of a ship/yacht/boat. Since you said you don’t have what it takes to join the NAVY or Coast Guard, I would suggest looking into getting a job on a tugboat or similar maritme industry occupation. That will give you an idea if its really what you want {living on board is not as easy as it sounds} Its more like surviving on board . You will have to start at the bottom . Anyway , that way if its not what you thought it would be you are not in the hole financially with a boat, and you can use the companies equipment to get experience while also earning a paycheck to finance the future endeavors. However let me say to you that if it is your dream to do this , if you really want to be "One with the Sea" you will find a way to do it. I think it is a very worthwhile endeavor and the experience you gain will be worth the wait once you arrive at the destination. Good Luck Bro!!