I always thought the Marinea project had potential other than the grandiose scale. Lots and lots of people purchase floating docks made of concrete. They are not out of reach for private persons, small businesses, and even private residences.
A shallow bank, in a place where there’s not a overwhelming amount of government interference, protected by a chain of islands has a LOT of technical options. Purpose-scuttled structures floated into place, jack-up barges, shallow draft anchorage of floating structures, artificial islands, all kinds of possibilities. Compared to the surface of the world, shallow banks are a tiny candidate pool of new living space, but in absolute terms at human scale, it’s still quite large.
It appears that part of the reason scuttled ships have had some mixed success in creating artificial reef structures, is that they are basically designed to roll with the waves. This doesn’t change once they are on the bottom. Caisson style breakwater/barge structures don’t seem to have quite the same problems, as evidenced by the Mulberry harbor experience.
A purpose-built live-aboard barge (or set of them) purpose-scuttled in Cay Sal would have a fairly reasonable price tag, especially compared to purchasing a private island, and has the advantage that you’re not stuck with only what nature randomly provides. You could build your shelter into the basic structure of the ‘island’ and therefore be much more secure against storms. The biggest technical problem for residing on the ocean (after reliable flotation) is fresh water and vegetation. A number of means of addressing this problem exist, however poorly understood and distributed.
Might be harder to do in the Pacific, simply due to being MUCH further to tow. The Pacific islands are also mostly stuck in a tribal government structure or with a government that recognizes tribal/communal land ownership legal structures, with very complicated land and fishing rights. Large swathes have been put of limits to residence or exploitation as marine sanctuaries. Doesn’t matter how good your intentions, anything new is verboten.
What does it cost to build a concrete barge?
As of December 1, 2014, the price for a new barge 16’ x 32’ x 6’ with 6" walls, is $97 per square foot for a total of $49,664. This price includes fusion coated steel reinforcing, two coats of Cold tar Epoxy or equal, 5/8" x 10" hot dipped galvanized anchor bolts @ 48" it the top of the walls, and one hot dipped galvanized mooring bracket in each corner.
The same barge with geopolymer concrete and basalt reinforcing rather than steel might differ a bit, but should be in the same realm. A barge that is designed to be floated into place and then settled on a shallow bottom might vary a bit more- thicker/thinner walls, perhaps less concern about quality control in thickness, because it doesn’t have to stay balanced for long. Slightly different outer dimensions or shape because it isn’t meant for hydrodynamic flow efficiency.
Portland market trends indicate an increase of $42,250 (12%) in median home sales over the past year. The average price per square foot for this same period rose to $324, up from $284.
Of course, outfitting a platform costs more than just building the floating part.