At first, I started thinking about “Ocean Republic” from the late 1980s, In March 1992, the document was published on “Fune no Kagaku” (Ship science)

There are various factors in that idea.

At that time, it is said that there is a global population explosion.
And I have joined sailing yacht club of MHI Nagasaki.
Then I felt the wind power is so huge.

And, of course, I think there was “Hyokkori Hyotan Island” that was broadcast on NHK in the 1960s, which we can’t forget in our age.

https://www.uta-net.com/movie/3875/

The image from the internet

Hyotan Island I repainted with the tools.