Top Hat Number 10 to be installed this weekend.

NEW ORLEANS – Undersea robots manipulated by engineers a mile above were expected to begin work Saturday removing the containmentcap over the gushing well head in the Gulf of Mexico to replace it with a tighter-fitting cap that could funnel all the oil to tankers at the surface.

If all goes according to plan, the tandem of the tighter cap and the tankers could keep all the oil from polluting the fragile Gulf as soon as Monday.

But it would be only a temporary solution to the catastrophe unleashed by a drilling rig explosion nearly 12 weeks ago. It won't plug the busted well and it remains uncertain that it will succeed.

When the cap is removed, oil will flow mostly unabated into the water for about 48 hours — long enough for as much as 5 million gallons to gush out — until the new cap is installed.

The hope for a permanent solution remains with two relief wells intended to plug it completely far beneath the seafloor.

"I use the word 'contained,'" said retired Coast Guard Adm. Thad Allen. "'Stop' is when we put the plug in down below."

If all goes well, it could still be a week before they really know if the cap is containing most of the spill, Coast Guard Capt. James McPherson said Saturday. Testing has to be done on the new cap if and when it's in place to make sure it can withstand the pressure of the gushing oil.

Crews using remote-controlled submarines plan to swap out the cap over the weekend, taking advantage of a window of good weather following weeks of delays caused by choppy seas.

The cap now in use was installed June 4, but because it had to be fitted over a jagged cut in the well pipe, it allows some crude to escape. The new cap — dubbed "Top Hat Number 10" — follows 80 days of failures to contain or plug the leak.

Feds cautious on timing for new cap in Gulf leak - Yahoo! News