The first enlisted women to serve aboard a Navy submarine have arrived and are preparing to sail on the USS Michigan.

The Ohio-class guided-missile sub is wrapping up a major maintenance period at Puget Sound Naval Shipyard and Intermediate Maintenance Facility. Among other work, living quarters were installed for up to three female chief petty officers and 36 crew members. The project reached a milestone Friday when the boat, which arrived in August, left dry dock and tied up at a pier.

The Navy in June 2015 announced the names of four chief petty officers and 34 lower-ranked sailors who were selected for USS Michigan gold and blue crews. They were chosen from 113 applicants. The two crews are comprised of 15 officers and about 140 enlisted sailors each.

Female officers — three per crew — have served aboard some Ohio-class subs, including the Michigan, since as early as 2011, but no structural changes were needed for them. That’s far from the case with female enlisted living quarters.

The shipyard, USS Michigan builder Electric Boat and the ship’s crew enlarged the forward washroom, added four showers by converting a bunkroom into shower space, split the aft washroom to allow for a shower and head combination and a watchstander head, and created a new bunkroom from the old crew’s study, the Navy said.

The two or three chiefs will share a living space and washroom. The others will split into nine-person bunk rooms and share a head.

The Navy estimated the cost of the reconfiguration at about $6 million.

Melissa Kittrell, the project’s work integration manager, said in a Navy release that it was exciting to watch history unfold before her.