PORTLAND – After three years, a man who works at the Portsmouth Naval Shipyard has found a submarine sunk off the Maine coast by the Navy during World War II for training purposes.

Joe Cushing – who lives in Strafford, N.H., – won’t disclose the sub’s exact location, but says it’s about 12 miles at sea from Portland.

“It was a good find,” he said. “We are excited to have finally located the thing. After you look for something for three years and you made a bunch of dives and you finally locate it, that’s a great moment.”

Cushing says the sub – called “S-21” – was used by the Navy to train pilots and destroyer crews to detect enemy submarines. He started his search in federal archives, and later learned that a salvager had found the sub in the 1960s but quit after one of his divers got killed.

Cushing got help from another technical diver, Bill Lussier, and a sonar expert, Garry Kozak, before hitting pay dirt.

“I was able to come up with a general location where the Navy had sunk the submarine,” Cushing said, adding the information was classified during World War II.

So far, Cushing said they’ve made several dives when the weather permits and will continue to research the site.

The submarine, according to Cushing, is 220 feet long, and the center portion of the ship has been opened up by explosives, which he believes was done by the salvager.

The Navy knew the general location of the sub, but after World War II, “They pretty much just forgot about it,” Cushing said.