Orion, it would be uncommon, I only know of the golden fleet that has one available and that is I would say under used. In posing this question I was thinking of having the Yacht be able to stay long at sea or remote places, stay in touch with the world if want to with modern communications and then, if need to go in person, would have the Seaplane to get in.
If I could have it all the Yacht would have both, so when you are closer to shore or civilaztion the heli would be used, or the plane to get deeper inland.
I think a Yacht would need to be no shorter then 80 meters to have room for the plane, and support space. What do you all think? I realy how this is going.