BOOTHBAY HARBOR — A ship designed to skim 2,500 barrels of oil an hour from the nation’s waterways, described as the world’s largest cleanup ship of its kind, was launched Thursday from a Maine shipyard as hundreds watched.

“It was a perfect launch,” said Ken Roberts of the Goudy and Stevens shipyard. “It went right down the ways just as slick as it could be.”

The 123-foot Valdez Star will begin its 42-day voyage in the fall for Valdez, Alaska, at the end of the Trans-Alaska oil pipeline, and will go into service in Prince William Sound.

The ship was ordered by Alyeska Pipeline Service Co., which operates the Alaska pipeline, before the Exxon Valdez spilled nearly 11 million gallons in the sound on March 24, 1989.

The Valdez Star is the largest oil spill recovery ship ever constructed to protect U.S. waters from oil spills, Ralph A. Bianchi, president of JBF Scientific Company Inc. of Southwest Harbor, said in prepared remarks.