First, if you think you don't have to feed a boat every day, you haven't owned one. There is a reason BOAT is an acronym for Break Out Another Thousand. That said, take a look at your plans, and consider a more reasonable plan. Something that will eventually give you the experience that you want, while sounding a little more financially reasonable than an outlay of $350k.
Let's assume for a moment, that you have access to a local marina. What about an investment in a small fleet, maybe 5 small boats, such as 14' Lidos. Try starting a day sailing charter
business with these. Get some skill running a business or the type you are hoping to accomplish. Prove your ability to run it, and add to your sailing experience. Then, in a few years, you can reasonably approach your father with a proven track record
, and discuss selling that business to start a full scale charter
Take a practical approach, and remember, since you are under 18, you can not enter into a contractual agreement anyway, so you will be limited in your involvement in any venture, until you are 18