Hi all, new to the forum, and the topic fascinates me. There are clearly a lot of high level thinkers here, and that's a pleasant surprise for an internet forum.
My credentials: I'm a water resources engineer with a masters in environmental fluid mechanics and a PE in several states. I also do bluewater sailing and gulf cruising, and my background is in farming and construction.
Some thoughts on this thread:
You need to take a step back and ask yourself WHY you're breaking the water at all in your breakwater. Do you really need to? The city is floating after all.
The ROI for a fixed breakwater simply isn't there. You're going to end up spending staggering amounts of money on your breakwater system, particularly if it's going to be moored in deep water near Tahiti. If you want your floating city to work, from a cost standpoint, it's going to have to behave more like a boat and less like a city, which means going OVER the waves, not through them. Instead of seeking inspiration in floating marina designs, seek inspiration in ways cruising boats weather hurricanes.
The thing that pops to me, is a Jordan series drogue. You let your city move with the waves, and dissipate enough energy with your drogue to make riding the storm out more palatable. And the energy you dissipate is distributed along the length of the drogue line.