The U.S. Navy has given another $5.1 billion boost to its high-priority Columbia class submarine program and its designer and lead contractor on the new class of ballistic missile subs, the Electric Boat division of General Dynamics in Groton. EB, with shipyards in Groton and Quonset Point, R.I., has started building the first two boats in what is to be a fleet of 12 Columbia class ships that will replace the Navy’s aging, Ohio class missile submarines. The $5.1 billion announced by the Pentagon this week enables EB to acquire parts, material and other long lead-time items for the next five boats in the class. One of EB’s challenges is finding and training qualified shipbuilders. It now employs about 19,000 in Connecticut and Rhode Island where, in addition to starting to build the Columbia fleet, it is continuing to build the Navy’s Virginia class of nuclear powered attack submarines. The company has said it won’t hit peak workforce until the late 2020s and, even then, expects to continue to hire about 2,000 a year to maintain it.