The Taiwanese vessel "A Whale" was deployed last week along the oil-slicked Gulf Coast. But it's been determined the skimmer didn't collect enough oil.
The U.S. Coast Guard says it was too big to maneuver around the smaller patches and ribbons of oil on the water.
Smaller, more agile vessels have been more useful in getting at the oil.
Nearly 33 million gallons of an oil-water mix have been recovered.