POPHAM BEACH — Hundreds gathered in Bath and at Popham Beach early Monday to watch the largest destroyer ever built for the U.S. Navy sail down the Kennebec River for critical sea trials of the costly and high-tech warship.

Roughly an hour after tugboats guided the USS Zumwalt away from the pier at Bath Iron Works, cheers erupted at Fort Popham when the 610-foot ship that looks like something from a sci-fi movie threaded the narrow passageway between the Civil War-era fort and Gilbert Head. The $4.3 billion ship then passed in front of crowds lining Popham Beach State Park before hitting the open Atlantic for its inaugural round of at-sea testing.

ZUMWALT UNDERWAY

THE zumwalt-class ddg-1000 AT A GLANCE

THE LARGEST: The Zumwalt-class DDG-1000 ship is the largest destroyer ever built for the Navy, at 15,000 tons based on the weight of the water it displaces.

HISTORY: Construction began five years ago on the ship built at Bath Iron Works. The ship is the first of three Zumwalt-class destroyers to be built by BIW.

WHAT IT’S BUILT FOR: It can reach speeds of up to 30 knots and operate in shallower waters than the reigning destroyer class, the DDG-51, Arleigh Burke. The Zumwalt is designed to fight in open water or support battles on land by getting closer to shore.

THE LOOK: The ship is a “stealth destroyer,” with a 1,000-ton deckhouse entirely enclosed atop an angular ship designed to sit low in the water. The antennas, dishes and other pieces of the ship’s communication and surveillance systems are tucked away, as are the “small boats” used to ferry special operations forces to shore.

UNDER THE RADAR: On radar, the ship looks more like a small fishing boat than a 600-foot warship. It has a radar cross-section that is one-50th that of an Arleigh Burke destroyer, and a lower profile on underwater sonar and infrared systems.

POWER UP: It is the first destroyer to have a single gas-turbine powerhouse for the whole ship, capable of producing 78 megawatts – enough electricity to power 780,000 100-watt light bulbs. That’s enough to handle the ship’s propulsion, weaponry and other electricity needs.

Emily Bankhead snapped pictures and excitedly directed the gaze of her 2-year-old daughter, Lily Jo, toward “daddy’s ship.” Bankhead’s husband, a Navy officer assigned to the Zumwalt, was among those on board for the sea trials.

“That was fantastic, seeing it come around,” Bankhead said of watching the massive gray warship emerge from seemingly just beyond the fort’s stone walls. “It was such an impressive sight.”

The “lead ship” of three Zumwalt-class destroyers to be built at BIW, the Zumwalt certainly makes an impression.

The ship is all smooth surfaces and angles with a 1,000-ton deckhouse that resembles a pyramid with its top cut off. Even the Zumwalt’s bow angles inward from the waterline to the deck in a revival of the “wave-piercing tumblehome” hull design that was largely abandoned for naval warships generations ago.

The result, according to the Navy and BIW, is a warship that slices through waves with less wake and will have a radar imprint of a fishing vessel – a 50-fold reduction compared with the Navy’s current destroyers. Billed as the Navy’s next-generation, multi-platform destroyer, the Zumwalt-class ships are designed to operate closer to land than Arleigh Burke-class destroyers while maintaining their capability to fight submarines, aircraft or other ships.

And the ship’s 78 megawatt powerhouse – large enough to light 780,000 100-watt light bulbs – powers everything on the “all-electric” ship, with excess capacity for weapons systems such as electromagnetic rail guns or laser guns now under development by the Navy.

TECHNOLOGY ‘KEY,’ PORTLAND STOPS

The ship is named for the late Elmo R. “Bud” Zumwalt Jr., a World War II veteran who went on to become the youngest chief of naval operations in U.S. Navy history and is credited with improving sailor morale and racial tensions within the service. The USS Zumwalt headed to sea for the first time on the 74th anniversary of the Japanese attacks on the U.S. naval base in Pearl Harbor, although a Navy spokesman said last week that the sea trials were not timed to coincide with the anniversary.

One Navy veteran, Richard Trask of Dresden, drove to Popham with his wife Monday morning to get a better view of a ship he had only seen from afar at BIW’s pier. Wearing a Navy hat and jacket, the retiree who served on five aircraft carriers during his career said he was amazed at the number of people who had made the same trip to see the Zumwalt’s first major voyage.

“It’s amazing,” Trask said of the ship. “The technology is the key.”

The sea trials will be used to demonstrate the Zumwalt’s hull, mechanical and electrical systems during what Navy officials have described as a “multi-day underway period.” The ship is expected to make several port calls in Portland, offering city residents a chance to see the unique-looking ship. The Zumwalt will then transit back up the Kennebec to Bath, where crews from General Dynamics-owned BIW and other Navy contractors will try to work out any bugs in the ship’s systems. The Zumwalt will be home-ported in San Diego after its official commissioning in Baltimore and the addition of weapons systems.

PROUD DAY FOR SHIPYARD WORKERS

“General Dynamics Bath Iron Works, the Navy and other naval contractors are currently on board DDG 1000 for its first set of sea trials. The men and women of BIW are proud to bring this lead ship to sea for its maiden voyage,” BIW spokesman Matt Wickenheiser said in an email Monday.

The voyage was a long time coming for staff at BIW and the Navy.

The Pentagon, responding to rising anticipated costs and the evolving needs of the Navy based on its perception of future threats, reduced the number of Zumwalts it planned to build from the original 32 to the three now under construction at BIW.

Construction of the USS Zumwalt began in 2009. Two more Zumwalt-class ships – the Michael Monsoor DDG-1001 and the Lyndon B. Johnson DDG-1003 – are under construction at BIW, as are three of the Arleigh Burke-class destroyers.

One of the dozens of people who gathered at the Bath city dock located just downriver from the shipyard early Monday morning was former BIW President Dugan Shipway. Construction of the Zumwalt was just beginning in 2009 when Shipway retired from BIW.

After watching the nearly complete ship float downriver – a trip he himself took several times aboard Arleigh Burke-class destroyers – Shipway said there were “6,000 very happy people” at BIW that morning, referring to the shipyard’s employees.

“It’s a huge, big day for the men and women of the shipyard,” he said.