BATH – The U.S. Navy has awarded a $208.1 million contract modification to Maine shipbuilder Bath Iron Works to design and build a Littoral Combat Ship, a new breed of speedy and easier-to-maneuver Navy vessel.

The Maine company, a business unit of General Dynamics Inc., will be the prime contractor for the project and is expected to perform 21 percent of the work on the ship, said Sen. Susan Collins, a member of the Senate Armed Services Committee.

The contract announced Friday calls for the fourth LCS to be acquired by the Navy. BIW will perform the work in Mobile, Ala., Pittsfield, Mass., and Bath. The project is expected to be completed by August 2009.

The Navy’s long-range plan calls for 55 Littoral Combat Ships, which are designed to meet threats posed by modern-day pirates and terrorists who turn speedboats into suicide weapons.

They are powered by steerable waterjets, so they don’t need propellers or rudders. With their shallow draft, littoral ships are designed for operations close to shore and to go more than 50 mph. Traditional destroyers have had the same top speed, about 35 mph, since World War II.