My concept, based on the patents and one of the conceptual designs by Wally Yachts...
Intended to be unpowered, nearly self-sufficient, premanently moored offshore. Hydrodynamics allow for the current to maintain a bow-forward attitude, the overall stability prevents an easy roll-over, the general design allows greenwater to shed rapidly, No hatches facing forward, or on top prevent easy water accumulation during adverse weather conditions. Double-hull ferrocement-like construction, using a proprietary technique I came up with in the last few days (not releasing significant details until much later), using Basalt rebar and preferably Geopolymer cement (formula still not completely finalized). Hull will be superinsulated, using flotation foam. Daily electricity will generally be wind and water-current generated, with some solar panels mounted atop the 'pilothouse' and living suite.
Biodegradable wastes will be handled by an advanced Anaerobic Methane Digester, followed by an aerobic phase, prior to use as hydroponic fertilizer, in the greenhouse. Greenhouse also acts as source for distilled water, using a simple 2-stage evaporation/condensation setup. Membrane-type molecular sieve will remove CO2 from the Biogas, and that will be used for atmospheric enrichment, within the greenhouse.
I intend to attempt to use an advanced thermo-acoustic cryogenic condenser to decrease the required storage space for the purified Methane. A nearly identical system may be used for liquified air, to be stored for simple expansion-refrigeration and backup energy supply (modified 'steam' engine generator).
Additional stabilization will include a hydrofoil-lke heave damping device, passive/active moving ballast system, using interconnected, partially flooded compartments. Induced airflow may present a potential energy source, using bi-directional turbine generators as the flow-restriction, during passive mode, and blowers will be used to forcebly control the tank levels, in active mode, using a method already in commercial production.