For a long time we favoured the shape of a sphere mainly because there were ready structures available used as pressure resistant LPG tanks. It would have measured 12m in diameter, the lower half would be filled with sand just before lowering while the upper half would contain two floors of living space. After discussing the idea with different engineers we had to accept that a LPG tank would need so many modifications that building a new one would be even cheaper. After receiving the first cost estimations we were pretty sure that it would be impossible to find funding for a civil structure of that scale.
To keep the initial costs as low as possible we decided to begin with a smaller version. It should have been 6m in diameter and have two blind doors to attach other modules one day. The idea was to use it as an ignition for potential participants to join the project.
I have to admit that we were not very enthusiastic about this version since it neglected the most important issue which was supposed to make it different to previous stations: the human scale. It would probably become a dead end to the whole project.
Michael Schutte, designer of Poseidon Resort, wrote me in 2011:
‘To keep it cheap you should think about rolled cylindrical sections – the compound curvature on your sphere is really tough to do in steel – the thicker it is the harder to form it as well.’
He also reminded us on the subject of the viewports:
‘Also makes it very difficult to install viewports as they need to be nearly flat or you start to get all kinds of weird optical effects in the acrylic.’
Still we favoured the sphere having many advantages:
- The ballast tanks would be integrated in the structure
- Therefore removing it would be easy = ecological
- The 12m version would serve the main idea of the ‘human scale’
- Jacques Cousteau used the same idea for ‘Conshelf III’
- It would be visually very attractive
The disadvantages were significant:
- Attaching other modules would weaken the structural stability
- It would be VERY vulnerable to drifts
- Towing would be very difficult and risky
- Landing would be very difficult and risky
- Difficulty to build it and to install any extras like viewports
Fortunately we never were in a hurry with the project. So we took a long time to find a solution for the disadvantages of the sphere and came in the end to a new draft (No. 4) that has the shape of a flat hangar and will be presented here soon.