Offshore positioning

Fugro set up a remote operation centre in Abu Dhabi:

The new ROC in Abu Dhabi is the latest addition to Fugro’s global network of ROCs, which now consists of eight centres operating across all four regions.

It is amazing to think of the development there has been in this operation since I first got involved in rig moving in the mid-1970s.
At that time Sylidis was the ruler of the market for terrestrial positioning system and jack-up rigs were slotted. (Cantilever came later)

Positioning a rig on an open location was done by getting a marker buoy “in the middle of the slot”. The buoy had been placed by a position survey team on a boat using Sylidis (or Mini-Ranger, if close to shore, or fixed platforms) Usually there would also be a range buoy 50’ from location, just in case the location buoy was missing, (stolen by fishermen, or got run over when approaching)

When the legs were firmly in the ground the survey boat would make runs around the rig to triangulate the position to confirm that we were within the tolerance.(usually 50’)
Since this was difficult to do in the dark, positioning the rig on location was a “daylight only” operation.

In the early 1980s it became normal to have the Sylidis placed on the rig together with a Satellite Navigation receiver and a couple of Position Surveyors. The buoy(s) were still pre-set, but the survey boat did not have to hang around to check the final position. That was done by averaging a number of positions obtained from satellite passes that was at least 15 degr. above horizon, which could take hours at times. (especially at high Latitudes)

When GPS became available it had an accuracy for civilian use of +/- 75 m. so it was not usable for positioning without a terrestrial correction, which the Survey companies had access to. It still require multi-pass average to get the final position, but at least this usually took minutes, not hours,

When I quite rig moving in 2010 the whole thing had changed. No buoy required and no need to be outside. All info was now available on a screen in real time and I could sit in the Jacking Control Room in air-conditioned comfort and give instructions to the tugs and the Bargemaster at the jacking panel without getting out of the chair, or even look out the window.

There were still two Position Surveyors though, but now even they have apparently moved ashore. (??)