With no intention of giving offense to anyone in particular, I note that a lot of folks on the forum tend to speculate wildly about things that already have answers.
Here’s a place to recommend sources of information on how to do things that would apply to building a structure on the ocean, anchored or free-floating, that would support long term living for humans.
(There, does that avoid overly narrow views and endless discussion of “what’s a seastead”?)
For example, I bought this book, and it has a great deal of useful information: http://www.amazon.com/gp/product/0849330521
Reading something like this an keeping an open mind allows you to see what is necessary to build something without closing your mind to non-traditional was to achieve the same goals.