Moon pool

Operational stability (moon pool or center well)... 

The pumping system can be used on almost all research ships, provided the vessel is equipped with a moon pool and a specific mounting plate. It combines the advantages of relatively low ship costs per sample (when passing from station to station) with the possibility of interdisciplinary studies. 

The drillfloor and the derrick (drilling tower), with pipe handling systems and the flare tower on the top, are located in the centre of the platform. In this area, we find the remaining systems, for drilling and mud treatment. Subsea equipment such as valve assemblies (X-trees) and blow-out preventer (BOP) are stored and handled in the moon-pool area below the drill floor. 

Accident risks in drilling activities on the semi are a concern. A special challenge is to secure safe handling of heavy subsea equipment in the moon pool area in the centre of the platform. Advantages with the semi are the shorter distances to the different workplaces and less movement due to heave. 

The much-closer Moon would have had a greater influence on the tidal rise and fall of the oceans. At the moment, the mid-ocean tidal rise and fall far removed from the land masses is of order 1 m but if the Moon had been formed at a distance of around 40 000 km the tidal variation would have been of the order 100-1000 m. Large regions of the Earth s surface would have had a refreshed water supply every 4 h in the extreme cases of the model. Only well inland on the early land masses would there have been a dry environment, perhaps with fresh water replenishment. The early ideas of Darwin called for a Tittle warm pool to act... 

---