To sustain food, water and fuel:
I would use techniques described in the book Sailing the Farm by Kenneth Neumeyer.
And I would use other techniques too. I would always observe and learn from the locals.
In French Polynesia I would do like the French Polynesians.
For food: I would fish. For water: I would desalinate seawater. For fuel, I would use
solar electricity and batteries, and sail and etc...
These technologies are good and there are many technologies are readily available.
There are many technologies that do not have to be invented or developed.
There are some other technologies too that are not developed and those could be developed.
Such as: OTEC (ocean thermal energy conversion) the temperature gravity wheel.
The temperature gravity wheel was featured in the tv series Mythbusters. It was declaired
a failure. Later on many successful devices were built and those have video recordings on
youtube. I happen to be one of those, who built a temperature gravity wheel that worked better
than the one by Mythbusters. Shortly after I built my version, other versions popped up on
youtube that were better than mine. One of them worth mentioning is by a youtube name:
These devices are super low maintenance, continuously running, very low temperature gradient,
zero emission heat engines. Such devices can be further perfected and developed.
(I would like to mention that the heat engine does not break the second law of thermodynamics.)
For water purification I would use the one by Kenneth Neumeyer: Sailing The Farm.
And I would also think in the direction of vacuum vapor compression devices.
On large scale, vacuum vapor compression, is an old technique used by WWII US Navy ships.
I would take the direction of using smaller scale devices. I would also use reverse osmosis
system, and I would never forget about collecting rain water.
Food, water and fuel are good to have. There is one thing that becomes necessary right away
is sanitation. All those living things (fish, sea mammals) that live in the water column use the
ocean for sanitation, whatever way they can. All the large ships use the ocean for their
sanitation purposes. I would want to develop a sophisticated way to shit, and deal with the product.
This is probably not a favorite subject to many people until it becomes a problem.
Cleaning up and keeping the environment clean has to be a top priority.
And I believe, I have to go further and closer to reality on the field of technology.
Building floating structures is necessary to be in the water.
So, some people are technology oriented and others are not. Politics is necessary for
technology to work, but it is not enough. Have to go further: some have to build the physical objects.
Politics has to serve the builders and the operators to build and operate the physical objects.
Politicians cannot rule by force. They have to serve to enable. This is not a new concept.
God speed to all.