Two industires with relatively low start-up costs and high demand: off-shore banking and "data havens." Both might have a comparative advantage on a seastead because they are so heavily regulated on-shore.  

But if I really wanted to make a fine living on a seastead and cared not a whit for my eternal soul, I'd open an offshore prostitution / opium den. Now there's a growth industry where lack of government regulation really makes a difference.

Any industry that is otherwise highly taxed, highly regulated, and does not need vast areas for production should be competitive on a eastead.

Most if not all Industry will require reliable power. In practice this means fossil fuel or a nuclear power plant.

OK, tht's the standard theory, which I think we're all aware of :)

•  What have you got, other than "meth lab"?

One option for a seastead business (still heavily tourism-centric) is charter fishing and scuba/snorkeling equipment rental and training. Someone who has a boat capable of doing these things would also have a comparative advantage as a ship-to-shore taxi in a specialization of labour scenario.

•  Not everyone on the seastead needs a boat capable of traveling long distances, in fact, relatively few do, much like inner-city dwellers rarely need an auto.
• The sea stead will most likley be small enough to make walking the quickest and most effieicnt form of moving around it, with perhaps some boats that moor to the underside like gondolas in Venice. These smaller boats will be for workaday movement in the vicinity of the seastead and utilitarian purposes like fishing, tending nets, lines etc.
• Of course, these other boats also serve as emergency life vessels in the case of a catastrophic failure of the seastead itself, to keep people alive long enough for rescue.

Another industrial possibility for a seastead might be asbestos disposal. The only real problem with asbestos and the reason it is banned is because inhaling it in particulate form over long periods of times causes physical damage to your lungs. It's not chemical damage- in fact, asbestos is fairly inert, chemically. It might be possible to find a method of disposal which not only is not harmful to the sea floor, but actively beneficial to permanent or semi-permeanent seastead mooring areas by providing a substrate upon which more marine life can grow, in the artificial reef model.

Experimental nuclear power. There is a South African company working on a Pebble Bed Reactor that apparently has had problems with activists/government for some time. They or others with similar needs/problems could surely use some real estate without most of those headaches.

Currently, most Copra traders in the Pacific merely collect it and take it somewhere, which often reduces the quality of the coconut oil produced to less than human-food-grade. I have found references to smaller processing plant equipment, that could easily be ship-borne. Such a mobile processing platform could cut out some middle-men, time, and spoilage, by processing the cargo picked up from one island while journeying to the next, then trading finished products like copra meal (animal fodder high in protein), soap, and biodiesel for the next island's raw materials. In the process, the ship supplies its own fuel, and builds a network of buiness relationships for other trading. The languishing copra industry is revitalized on a local scale with greater profits going back to the individuals farming the coconuts, higher standard of living, and the supply-market loop is cut to a fraction. Several such ships operated as one corporation form a seasteading community that keep in touch and meet up from time to time to trade labour specialties, social interaction, information, and corporate business.

Other ships visit more sessile seasteads and pick up fish products, pick up and process human/biological waste with methane digesters, trade off or sell what they don't need of both methane and organic fertilizer to the coconut farmers in return for other products or cash.

Recycled plastic fiber clothing. If  a Seastead were to specialize in this type of clothing manufacturing, and a service were instituted to collect the plastic bottles from all over the Pacific (charging for removal) and then recycled into clothing for sal eback to Islanders. It might be a viable bueinss. Again, this collection service might be a mobile platform, it might be a service that a ship-shape seastead performs for sessile seastead. Early versions of this technology were criticized for lack of fire retardant capability, but selling it to people with no other options and who are fully informed of fire hazards would not pose a moral quandary. Also, there are now techniques that can be incorporated into the process to mitigate this. Seas steaders themselves would probably be a good market for this, as one of the best sources of lcoally-manufactured clothing (and clothing may be less important on many seasteads in mild climates than it is currently in the United States, for example.)

Mobile processing ships have been increasingly used in the Alaskan fishing industry though, so there is a sound business case behind it.

Might a business forum  be a good idea?  If seasteading is going to move from being a philosophical discussion to a reality, isn't the basis or raison d’être going to be commerce? I'd think that that would actually come before the design of a physical platform. I understand that a design parameter is to have flexibility, but the incremental approach would lead me to think that showing that a platform can be self supporting (financially at first) is the first hurdle. Commerce or business will be the major occupation on a seastead, not government.

I would think that the business strategy guy/gal would come before a chief scientist, or engineering director. Those positions are the "how". I guess the social movement might be the "why" but I think that's too vague to translate to a floating community. But the "what" seems to be being short changed. What, exactly will be the revenue sources? I've read the "ventures" page. For a business to succeed, it needs a strategic advantage. A seastead will be pretty limited here. Golf course? A simple comparison of popular courses would show the impracticallity. Medical and Health Care? There might be a market for high end cosmetic surgery. The isolation, if adequate facilities are supplied, would be an advantage. Oceanic research projects? There is not much to study in one place in deep water. That's why it's done from ships.

Aquaculture? Maybe. OOA (open ocean aquaculture) seems well suited. There is capital available. The market is growing. Deep cold water for freezing energy is close. It would need to be processed so it would make sense to buy wild caught and process and market it also.

Cargo transboarding? no comment. Casino? You will need a good reason for customers to travel the distance. My sense is casino goers won't be that interested the concept. Diving and Shiphandling school? I've been to both and don't see any reason to go to a seastead for it. Maybe commercial diving. The ballast tanks could be configured as training tanks and NDT (nondestructive testing/inspection) apprenticeships offerred. This is a small potatoe though. Surfing ? You would probably need a medium nuclear power plant to stationkeep an open ocean wave breaker. It's also the opposite of the objective. Breaking waves cause the damage. If they are not breaking, they're basically swells not waves.

Maybe a valid approach would be to examine current income sources or businesses (successful ones) that operate on the oceans. Developing ones that show promise (that is are already attracting investment capital) should be included probably. A SWOT analysis might be a good idea.

So if TSI is to move from a philosophical discussion to a floating seastead, would more of a focus on the economics be in order? I suggest a business forum.