BP Plc Saturday launched another stop-gap measure to capture more oil from the Gulf-of-Mexico gusher, removing a defective cap as the first step in replacing it with a tighter one.

The new cap is intended to allow ships on the surface to suck up more oil than is currently being collected from the 82-day-old oil leaky well rupture.

But it could be at least another four to seven days before the new cap is installed, meaning oil will once again flow unabated into the Gulf of Mexico and onto the coastal areas that are already the scene of ecological disaster.

Before the new cap can be installed, part of the blowout preventer (BOP) — the equipment that failed to shut down the well in the April 20 explosion — must be removed. Underwater robots were using hydraulic power to disconnect the bolts there, Kent Wells, senior vice president of BP Plc told reporters.

Meanwhile, BP has made progress in hooking up a third oil recovery ship, the Helix Producer, Wells said. The new connection was in the “final lockdown procedure” and would on Sunday start collecting from the end of the so—called kill line that leads off to the side of the BOP.

BP estimates that collection by the three vessels — the Helix Producer, the Q4000 and the Discoverer Enterprise, the only ship to connect directly to the cap — will increase the amount of captured oil to between 60,000—80,000 barrels a day, more than the estimate of how much oil is currently being spewed into the Gulf.

Wells said BP would try to capture as much of the unrestrained outflow as possible during the days the main cap is removed.

“We’ve amassed quite a skimming fleet near the location, so as we see oil coming to the surface, we’ll be ready to skim it,” he said.

Oil has been gushing from the well since end—April, when the rig exploded and sank, causing the worst spill in US history that is leading to massive ecological degradation in the ocean and along the coastline of five Gulf states.

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