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If we use one or more columns (spars/trusses) to get low waterline area, we will have high draft, which is a problem for constructing large seasteads in shipyards, and for small recreational seasteads which need to be able to dock at a regular marina.
There are several different options:
Jack-up / Jack-down
Jack-up/jack-down design (like a jack-up rig). Here the top deck can be set at any height along the columns. For low draft we jack it down until flush with the bottoms, for operating offshore we jack it up until flush with the tops. This is similar to the towing option above, except with top hull on top of lower hull, instead of next to each other.
Detachable Top Hull, Column Remains Vertical
Detach the top deck (after deballasting). I don't like this - where do we leave the columns? Scary, dangerous. One option is that we then reballast the column + lower hull until the lower hull is at water level, and we tow this behind the top deck. (will require considerable buoyancy to offset ballast weight).
There could be a joint allowing the columns to rotate, but more likely they would just detach, be turned horizontal (by inflating buoyancy at the bottom to lift the ballasted end to the surface), and towed. For small platforms which will do this more frequently, there may be a way to lock the columns into place horizontally.