New Orleans - With hurricane-whipped waves pushing more oil onto the Gulf of Mexico's once-white beaches, the government pinned its latest cleanup hopes Wednesday on a huge new piece of equipment: the world's largest oil-skimming vessel.

The Taiwanese-flagged former tanker named the "A Whale" is the length of 3½ football fields and stands 10 stories high. It just emerged from an extensive retrofitting to prepare it specifically for the Gulf, where officials hope it will be able to suck up as much as 21 million gallons of oil-fouled water per day.

"It is absolutely gigantic. It's unbelievable," said Louisiana State University environmental sciences professor Ed Overton, who saw the ship last week in Norfolk, Va.

As the monstrous vessel made its way toward the Gulf coast, large waves churned up by distant Hurricane Alex left Alabama beaches splattered with oil and tar balls the size of apples. The rough seas forced most smaller skimming boats into port for a second consecutive day, putting many cleanup crews at a standstill.

The ship looks like a typical tanker, but it takes in contaminated water through 12 vents on either side of the bow. The oil is then supposed to be separated from the water and transferred to another vessel. The water is channeled back into the sea.

But the ship has never been tested, and many questions remain about how it will operate. For instance, the seawater retains trace amounts of oil, even after getting filtered, so the Environmental Protection Agency will have to sign off on allowing the treated water back into the Gulf.

"This is a no-brainer," Overton said. "You're bringing in really dirty, oily water and you're putting back much cleaner water."

The vessel, owned by the Taiwanese shipping firm TMT Group, was completed as a tanker earlier this year in South Korea.

But after the Gulf spill, the company's CEO and founder, Nobu Su, ordered it changed into a giant skimmer.

The vessel was sent to Portugal for the refit and embarked for the Gulf as soon as it was finished.

The ship was expected to arrive Wednesday in Louisiana coastal waters, where TMT officials planned to meet with the Coast Guard to plan a tryout of the ship.

The Coast Guard will have the final say in whether the vessel can operate in the Gulf. TMT will have to come to separate terms with BP, which is paying for the cleanup.