DCNS said the hull section for the Barracuda class attack submarine is made of steel alloy. It measures about 29.5 feet in diameter by 13 feet in length and weighs 40 tons.
It will form part of the aft half of the hull, immediately behind the nuclear reactor compartment and will eventually accommodate the suspended block containing the electrical distribution plant.
Fabrication of the remaining hull elements for the submarine named Duguay-Trouin --20 other hull sections and four interface pieces -- will follow in the next few months, the company said.
The Barracuda program, led by the French defense procurement agency, calls for delivery of six submarines from 2017-28.
DCNS said construction of the Suffren, the first in the Barracuda class of submarines, is also on schedule at its Cherbourg center.
The Barracuda submarines will be a key component of the French navy's force projection assets and will carry MdCN cruise missile and other armaments.