I'm attempting to work out a formula for a low-cost geopolymer. Right now I'm fighting chronic fatigue and trying to get some small-scale grinding equipment to mill the granular clay and some of the chemicals, but, they are available in powdered form, when you buy in bulk. Consider the cost of concrete is cheap, but the additives are expensive, vs stuff like caustic lye, diatomaceous earth, and Fuller's earth, which are fairly universally available and are so 'Basic' in pH that they all-but preclude any corrosion of steel rebar and mesh.
If I can hit the right formula, the technique is still that of building in ferrocement. The alternative, IMHO, is ferrocement, which is typically quoted as cost-effective at hull sizes greater than 25-35 feet.
The advantage of streamlining for better stability and being able to maintain a direction, based on currents, will assist in greenhouse orientation, yet the ability to weather-vane under changing sea-states and wind conditions will aid safety.
Personally, I expect to have thrusters for minor maneuvering, but be towed to a permanent mooring. In the event of a need to move, towing will be more cost effective, than maintaining a marine drive-system, while remaining stationary for great lengths of time.
As a ship-like structure, it will meet one set of inspection standards, but as a non-powered, permanently moored structure, it will have fewer licensing requirements, and as a non-shore-connected, self sufficient structure, it avoids a number of marine licensing and habitat pollution problems.
The combination of descriptive issues should create a need for a definition as a seastead, which would further aid the general cause of seasteads and seasteading.
It requires exactly the same sort of convoluted reasoning that has given rise to many new terms.
Another benefit of the bulbous bow is the way is can also act as a forward attachment point for something like the 'wave-dragon', wave-powered electricity generator.