FLIP

The FLIP ship (FLoating Instrument Platform) is a ship that can transform into a buoy to create a stable research environment. Scripps Institution of Oceanography.

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It operates based on the same physical principles as a SPAR platform as used for oil drilling, but at a smaller scale. (a typical SPAR has a 200m draft, FLIP has a 100m draft.)

It demonstrates the possibility of scaling down SPAR platforms, but the conclusions to be drawn are largely negative, from a seasteading perspective.

Con:

• Getting a ship of this kind built in nowaday's dollars would be very expensive
• The total amount of real-estate obtained is minimal

Pro:

• It works, and is more stable than would be required for seasteading purposes

Conclusion: If optimized for cost and living space, instead of research purposes, one could undoubtly do a lot better on the former metrics, but good enough seems questionable. By merely considering the ratio of construction material (steel!) to real-estate, economic viability seems implausible.