Groton — Now that the bow has arrived, Electric Boat has all the sections it needs to assemble a new Virginia-class submarine.

The 113-foot bow for the North Dakota (SSN 784) could be seen on the northern wall of the graving dock outside the shipyard Friday. EB employees prepared to bring it inside the main construction shed to outfit it with the command and control and weapons modules in the coming weeks.

It arrived by barge from Newport News Shipbuilding in Virginia last week.

"All four modules of the ship are now in the same ZIP code," said Cmdr. Douglas Gordon, the sub's commanding officer. "It's pretty exciting for me to see the whole ship all in one area."

The redesigned bow is the feature that makes the North Dakota different from any other ship in the class so far. The North Dakota is the first ship of the third group, or block, of submarines that EB and Newport News are building.

All of the Block III submarines will have a bow with two tubes that hold 12 missiles instead of 12 vertical launch tubes. The components in the bow are configured differently to penetrate the hull fewer times. And, the parts are lighter, cheaper and last the life of the ship, said Chris Cameron, the Virginia-class construction program manager at EB.

These changes reduce the cost of the bow by about $40 million per submarine, Cameron said.

Cameron said the work on the pressure hull should be finished in the first quarter of 2013. Nine submarines are now in various stages of construction at EB and Newport News, from the Minnesota (SSN 783) through the unnamed SSN 791.

The crew of the North Dakota is training in preparation to take the submarine out to sea for the first time for sea trials in early 2014, Gordon said. The North Dakota should join the fleet that summer, he added.

Testing the new systems, Gordon said, will be a highlight of his career because the results could influence how the rest of the submarines in the block are built.

EB built the USS Mississippi (SSN 782) in 62 months and delivered the submarine to the Navy in May. The goal is 60 months. Cameron said the North Dakota is on schedule, but it's too early to say whether EB will reach the construction milestone on this submarine.

j.mcdermott@theday.com