Bob Grantham, spokesman for Taiwanese shipping firm TMT, says the company's vessel, dubbed "A Whale," will need further testing off the coast of Louisiana.

Grantham said in an e-mail Monday that conditions in the Gulf over the weekend were too choppy to get definitive answers on the vessel's capability.

Billed as the world's largest oil skimmer, "A Whale'' is supposed to be able to suck up 21 million gallons of oily water per day.

Grantham says testing will resume as soon as the water is calmer.

Cloudy skies cast a pall over South Florida beaches and rough seas hampered clean-up efforts in the Gulf -- even as crews were hoping a massive new skimmer would get the government green-light to join the fight against the growing oil spill.

Rough seas also kept clean-up vessels idle off the coasts of Florida, Alabama and Mississippi over the holiday weekend, officials said. The current spate of bad weather is likely to last well into this week, according to the National Weather Service.

Among the ships that continued to work the spill off the coast of Louisiana was a converted oil tanker called "A Whale." It's makers, Taiwan's TMT, say the craft can process up to 21 millions gallons of oil-fouled water a day.

"A Whale'' had undergone tests in a patch of water close to the wellhead over the weekend as the government tried to determine the vessel's effectiveness. The ship is also awaiting approval from the Environmental Protection Agency.

On Sunday, Florida's top emergency official downplayed a recent study that suggested oil from the gulf spill could get sucked into the loop current and be dragged through Florida's Keys and up the state's east coast.

The National Oceanic and Atmospheric Administration has estimated the likelihood of oil hitting South Florida's beaches at between 61 and 80 percent -- albeit with minimal or no environmental damage.

Florida's Director of the Division of Emergency Management David Halstead said the study was based on computer models that do not fully reflect a powerful eddy off Florida's gulf coast that is keeping the oil out of the loop current.

"At this time, there is a loop current ring that is not attached to the main loop current channel in the Florida Straits and there is currently no strong evidence to support that this feature will reattach in the near future," Halstead said in a release. ‘‘The State of Florida is aggressively monitoring the Deepwater Horizon impacts, utilizing air, water and land reconnaissance and is prepared to respond, should conditions change."

NOAA spent two weeks creating 500 models, using 15 years worth of weather and ocean current data, to predict where the oil gushing from the well will end up.

While the study suggests that Florida's Keys and beaches along the east coast are vulnerable, it also found the environmental impact would be minimal.

"Any oil reaching this area would have spent considerable time degrading and dispersing and would be in the form of scattered tar balls and not a large surface slick of oil," the agency wrote in a release.