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Close Approach With Oil Rig

A drilling rig was engaged in operations in a designated offshore oilfield. Its location had remained unchanged for more than four months and a two-mile radius safety zone had been established. This information was adequately promulgated to mariners. Despite these measures, on a clear day, the rig's crew was alerted to a cargo vessel that was approaching with a closest point of approach (CPA) of 0.3 nautical miles. It was observed that the ship's AIS was not operational, and general calls on the VHF went unanswered.

The rig's standby vessel was then sent off to intercept the cargo vessel and after closing with her, called her by name and also sounded the danger signal of several rapid short blasts at close range. The cargo ship made no attempt to respond and continued on her dangerous course, passing about two cables off the rig despite there being unrestricted sea room to seaward of the rig.

                                      (from the site: www.nautinst.org - MARS Report 200736)