Aloha and welcome aboard!
Management is what you are wanting to strive for but even with a college degree you will be expected to start at the bottom and work your way up. My advice is to go to several of the yacht clubs and ask around. Take whatever job you can get and if it isn't to your liking and they won't promote you within 6 months then move on to the next club until you find what you are looking for.
Sometimes, when the economy is good, City, County or State marinas
are hiring. That would garner the best benefits but the basic pay may not be the best.
Good luck in whatever you may try. Persistence is the key to success and the best thing to learn is to show up on time and do the best you can at whatever task you are given.