The whole point is a monolithic cure: shell and liner set as one continuous body, with no cold joints to leak or crack. That single requirement drives the entire method - an inflated balloon form hung from a gantry over deep water, sprayed in continuous lifts, cured, then lowered onto the sea it was built above.
Step through the build, or auto-play it. Each stage is chosen so the next layer bonds to the one before, so the finished sphere behaves as a single body.
| Stage | The engineering reason |
|---|---|
| Gantry + seabed guide wires | Holds the form dead still against wind and current for the whole pour and cure - roundness is everything for buckling. |
| Sewn balloon, seams on the stress lines | Cut gores and weld so seams follow membrane stress; an equatorial belt and a nadir tether force a true sphere, not a pear. |
| Low inflation pressure (~2-4 kPa) | Just enough to hold shape without over-stressing the fabric; regulated and logged for the entire cure. |
| Fibre mesh + carbon keel patch | AR-glass or basalt mesh carries tension; carbon tows go into the keel where you later want conductivity for thermal exchange. |
| Shotcrete in continuous lifts + retarder | The set retarder keeps each lift "live" so the next bonds into it - no cold joints, one monolith. |
| Wet-cure, then bonded aircrete liner | Pouring the insulating liner onto still-green concrete fuses structure and liner into a single body. |
| Lower down the guide wires | No crane lift, no roll: the sphere descends onto the water, tanks are commissioned, trim is set. |