BATH – A massive dry dock headed for the Bath Iron Works shipyard is due to begin its journey up the Kennebec River on Sunday.

Because of tides and weather, the trip upriver is expected to take about four days.

The floating dock is an integral part of the Navy shipbuilder’s $240 million modernization effort. It will provide a level area where vessels can be assembled and launched. The level system is considered more efficient because ships that are launched down an inclined way cannot be returned to the building way.

It took about 18 months for Jiangdu Yuehai Shipbuilding Co. of China to build the 750-foot-long, 180-foot-wide and 77-foot-high dock. The dry dock underwent sea trials last May and began its journey to Maine in late August, but was delayed for several weeks by typhoons.

Tugboats hauled the dry dock from Shanghai to India. From there it traveled to Cape Town, South Africa, before crossing the Atlantic. When tugboats bring the dry dock to its final destination at Bath’s waterfront, it will have traveled 15,675 nautical miles, said Cliff Yopp, a spokesman for the U.S. Coast Guard.

One of the largest pieces of equipment to navigate the Kennebec, it has a capacity to hold 28,000 tons and is longer that the 500-foot Arleigh Burke Aegis class destroyers BIW builds for the U.S. Navy. It will float in the river near a 15-acre shipbuilding platform.

“It will have an amazing visual impact. I think a lot of people will be in awe of it,” said Gary Anderson, a neighborhood watchdog for the project. “It will become the seventh wonder of Maine, at least until it starts to rust.”

The dry dock’s arrival signals the final stages of the shipbuilder’s modernization project. It will replace BIW’s Portland dry dock that is being phased out.

“The dry dock is the centerpiece of our new facility,” said spokeswoman Susan Pierter. “It will give us the flexibility of being able to transfer ships in and out of the water. We’ll become much more efficient.”

There will be three ways for shipbuilding and repair on the new platform. Vessels will be moved to the land transfer facility to the dry dock on a roller system. Once the ship is inside, the dock can sink to allow the launch. It also can be used to retrieve ships from the river and move them onto the platform for repairs and maintenance.

But not everyone is happy about the imminent arrival of the dry dock, which will be positioned permanently in front of Bath’s South End neighborhood.

The shipbuilder promised to build a 10-acre park on Washington Street for residents. But some fear their river views will be ruined by the hulking structure.

“I am going to lose my view of the river,” said Jim Kenney, who is trying to sell his two-story home on Washington Street. Kenney said three potential buyers said the prospect of looking onto a seven-story-high dry dock is not appealing.

Shawn and Molly Carlson have left Bath altogether. They sold their Washington Street home a year ago because they feared property values would plummet.