A 15 meter boat is Too Damn Big. If you can't handle it on your own, in a stiff breeze, don't even bother. If a 30 footer is too small for your crew, then better to get two boats instead.
See that's what I'm talking about. That sounds like a yes vote for a new thread! It seems like there are a surprising number of people here who are interested in yachts/boats.
Once you get into boating, everybody knows, it is never big enough. You'll always need a bigger boat.