 Why does Martin prefer to live on the yacht?
Though they were in the house with him, in their minds and in their talk they were living in another world—a world of warmth and peace and plenty where nobody worked, except in the government service or the essential professions. When Martin was sixteen, Raymond took him aside for the talk Ninian had promised five years before. And, on those worlds, it's far cheaper to use native labor than to ship out all that expensive machinery. In that way, there would be no space-drive, and, hence, the Terrestrials would never get to the other planets and oppress the local aborigines. Induced , Martin knew, could have meant anything from blackmail to the use of the iron maiden.
 Martin is used to being isolated now. The people on land live in a different world than he does.
 Martin is used to being isolated now. The people on land live in a different world than he does.  The people on land were always at war. Martin wants no part of it.  The people on land are too different from the cousins. Living on the yacht avoids questions from locals.  Martin thinks being on the ocean will make it harder for Conrad to find him.