> Couldn't they have just as easily built a tall floating rig that could be dragged by the same tugboat? Why do they even need to change to boat form? Can't they tug it when it's vertical?
Gigantic drag, low stability, and inability to enter ports and harbours when you have a 100ft draft.
> Drilling platforms are stable floating structures aren't they? They consist of a stable floating upper platform.
"Truss and spars" platforms usually have the truss floated on its side and the modules mounted on top of it once it's been floated and ballasted in place. Semi-subs can be tugged into place but that requires big tugs (multiple ~20khp units) and is very, very slow, to attain the speeds at which you can tow RP FLIP (7~10kt) you need a heavy lift ship.
These are not the kind of expenses oceanography can usually afford. Not to mention the semi-sub itself would be significantly more expensive than RP FLIP was, a semi-sub is more than half a billion, FLIP's original cost was about half a million.
Gigantic drag, low stability, and inability to enter ports and harbours when you have a 100ft draft.
> Drilling platforms are stable floating structures aren't they? They consist of a stable floating upper platform.
"Truss and spars" platforms usually have the truss floated on its side and the modules mounted on top of it once it's been floated and ballasted in place. Semi-subs can be tugged into place but that requires big tugs (multiple ~20khp units) and is very, very slow, to attain the speeds at which you can tow RP FLIP (7~10kt) you need a heavy lift ship.
These are not the kind of expenses oceanography can usually afford. Not to mention the semi-sub itself would be significantly more expensive than RP FLIP was, a semi-sub is more than half a billion, FLIP's original cost was about half a million.