Electric Boat has increased its employment in Connecticut by about 270 since the beginning of the year, as it continues to hire engineers and designers, spokesman Bob Hamilton told listeners on a conference call for district residents hosted by U.S. Rep. Joe Courtney, D-2nd District.

The growth has been driven by the need to design the next generation of the Navy's nuclear-armed submarines, the largest built for the service. There are 14 Trident submarines and four cruise missile submarines, all built in Groton, known collectively as the Ohio class submarines.

The Navy plans for the first Ohio Class replacement to be built in 2021. No decision has been made about where those subs will be built.

Hamilton told about 6,000 listeners on the call last Thursday, detailed in a release from Courtney's office Tuesday, that 222 engineers were hired this year, and 119 more are in process of being hired. The contractor has also hired 91 designers.

The combined engineering and drafting workforce is now 4,819, up nearly 300.

The administration has asked Congress to approve close to $550 million for design work in the next fiscal year.

Hamilton said in an earlier interview with the Courant that the possibility of sequestration — which would cut $500 billion from Pentagon budgets over 10 years, starting in 2013 — is not slowing hiring at Electric Boat, a General Dynamics subsidiary.

The blue-collar jobs in Groton are also up from the beginning of the year by more than 100 positions. There are 2,100 tradespeople at the company in Connecticut. Courtney said there would be even more manufacturing workers at the site in 2014, when the shipyard will see the full effect of the two-submarines-a-year-pace. Early work on assembling a submarine happens in Quonset Point, R.I., where modular pieces of the sub are constructed.

The company projects that by the end of the year, a majority of trades personnel who have been laid off or furloughed will be recalled.

Courtney said a $6 million contract for maintenance of two submarines will also support hundreds of jobs in 2013.

The Defense Appropriations bill for next fiscal year, which has not been voted on yet in the Senate, increases the Pentagon's plan for submarine building from nine over the next five years to 10. The House has approved that level of spending on submarines.