What you are looking for is called a slipform. The CN Tower took about 8 months to pour the main column this way. It was the tallest freestanding structure in the world until last year, so I would hope it is reinforced concrete 
I think that the Spar Buoy could be made of Ferro Cement, but I question if it will be easier, lighter or cheaper. I think alternative materials should be considered.
This huge tower is expensive and requires a big ballast which decreases payload. We need more simpler and robust design like a box with a few internal sections, very like the ARK. In case of very bad weather people can hide inside as we do at land
Undersea part of tower contunues very deep , it makes repair difficult
If I remember correctly, the Ark used a reactive water ballast to remain steady in storms, in the form of a large water tank designed to have a flow period half of the rocking period of the boat itself. When the ark heaved, the water in the tank would rush from one side to the other and compensate. Or so I think. Maybe that’s completely implausible, but I would love to test that sort of thing in a wave tank.
Well, that sort of depends on the size, doesn’t it? 100 meters is pretty deep for divers to reach, but if a sizable bit of the lower portion is either solid ballast or a tank designed to be flooded, there is less to inspect. There’s also a current ly useful technology for inspections: a robotic camera, and this depth is hardly anything to that technology.
Even 35 meters is difficult to dive, and you need to dive not only for inspection, but to repair cracked concrete
True, but designs should take that into account.
- Cracks in solid ballast compartments are not as much of an issue, as they don’t have to be water-tight.
- Cracks in water ballast compartments depend on how big they are and if your pumps can keep up with them for the periods of time they need to be pumped out, and if the crackwill affect structural inetegrity under a changed condition susch as pumping them dry.
- Cracks in buoyancy ares, particularly in living quarters are the biggest concern
- The design lifetime may take it into account that eventually, this sea stead is going to be completely or semi-scuttled, and therefore when the predicted failure time is nearing, it is taken to its final position, i.e. shallow water where it becomes either an artificial reef or an artifical island
It also depends on the material. Robotic undersea welding seems like a near-term possibility.
Cool, thanks for that link and info. Looks like you can even build tapering and complex structures with this method.
35 meters is easy, very easy. 100 meters is getting difficult. Such an installation would certainly have onboard intervention technology like divers (professional, not scuba) and ROV’s. Really though, stability will govern, not diver depths.
Sundiver 4 years, 12 months ago.
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