There is no doubth that there are hundreds of methods you can use to build someting that floats and breaks the waves. The key issue is that the structure must be big compared to the wave it breaks - as we know now oceanic waves (draupner wave) can reach 30m height which means that a 200 m ship is still quite small compared to it - as the example of the Bremen and the Caledonean Star - both hit by such waves - shows even a ship of that size will be burried completly by such a wave and be broken by the wave instead of breaking the wave.
So for a effcient sea break you need to exceed the size of a huge ship considerably. To build it you need a awful amount of material - there is a good reason why rebar mesh and foam are only used in builds where the material quantity is low - nobody builds something out of foam meshwire and other composite materials that exceeds 10m size - it would just be too expensive and to tedious in material handling.
Big structures like cities are never built out of "exotic materials" they are built out of concrete which is a relativly economic and easy handling material. Even so housing cost in City centers is more than average people can afford.
Nobody could afford the squaremeter prices of a apartment built on a floating island of hundreds of thousands of tons of meshwire foam and biorock.
The key factor is / cost per ton / - if biorock would bring up a competitive figure breakwaters and harbor installations would be built out of biorock by now - it is out there for several decades.
A good starting point would be to realize that people can afford living in concrete honeycomb and shell structures on land right now. It is also clear that concrete honeycomb and shell structures can float maintenance free on the ocean for at least 200 years which gives them "real estate endurance quality" - on contrary to steel structures that will sink after a single decade of no maintenance.
Evolution is always taking what is there right now and develop it a step further - so what we can expect in the next decade is that our coastal cities will grow out to sea in floating marina like developments - still using the same building materials usual right now - basicly concrete adapted to marine requirements.
I have asked Thomas Goreau, originator of biorock and a noted scientist, why we would need more than thin aluminum wire and electricity and time to make the biggest biorock island imaginable. I am waiting for his reply. Meanwhile it seems to me that if a low voltage current can be run through an existing reef, without iron in it, to save the coral, as Goreau has done,how much more could a current be run through thin wires which would gather aragonite to themselves indefinitely, thickening the aragonite over time. As I wrote to him our motto must be, keep it simple stupid. It is certainly not simple to ship in concrete. Whereas we could run thin wires across a circle the circumference would be geodesic spheres, very high, large, and resistant to waves, even the largest, while being light and strong. Tell me that I am wrong. Yours very truly, Vincent Flack at roomforroosevelt@gmail.com