The 96-foot tugboat Challenger was born in August 1944 in Wilmington, California. It died about 4 p.m. Saturday, Sept. 12, 2015. It was 71 years old.

“I walked into my home from being out,” said Christine Kleinheinz, who lives in the home nearest the spot where the Challenger sank Saturday in Gastineau Channel.

“I walked into the kitchen, looked out my window and saw the boat on its side with the water up to basically the side of the boat already,” she said. “I called the Coast Guard right away, and then I started videotaping, and in 4 minutes, the whole boat was submerged.”

Only the tip of the tugboat’s mast extends above the surface of the water at high tide; much more of the boat is exposed at low tide, making it visible to many homes and businesses near the Juneau-Douglas Bridge.

The Challenger had been a regular fixture in the channel for months, Kleinheinz said, and she characterized the boat’s owner, artist R.D. Robinson, as a “nice guy.”

“He kind of parked it out here just to keep it out of the way,” she said.

By press time, Robinson had not responded to a phone message seeking comment. There was no indication that he was onboard.

Petty Officer 2nd Class Brandon Daves, on duty Saturday evening at the Coast Guard Sector Juneau command center, said information was still coming into the office.

“Here in the next few days, our response department will most likely be looking into salvage efforts,” he said.

In the hour after the Challenger sank, a small-boat crew from Coast Guard Station Juneau marked the wreck with a buoy and a blinking light installed on the ship’s mast.

“It shouldn’t be much of a hazard for almost anyone,” Daves said, but the Coast Guard installed the warnings and issued a radio broadcast as a precaution.

Candice Bressler, a spokeswoman for the Alaska Department of Environmental Conservation, said it wasn’t immediately clear how much fuel or lube oil was onboard. A sheen was observed near the Juneau-Douglas Bridge, but Bressler said a pollution investigator aboard the Coast Guard boat “determined the sheening is minimal and unrecoverable.”

“The Coast Guard and DEC will be monitoring it over the weekend,” she said.

The Challenger was born amid the World War II building boom when it was launched as TP-126, a wood-hulled tug/passenger boat for the U.S. Army.

In 1946, the Challenger was decommissioned and sold to a firm on Vancouver Island. It worked in the waters off British Columbia and Washington state until 1983, when it was sold to a private owner.

In 1985, the Challenger was converted into a “bunk and breakfast” in Seattle’s Lake Union. Owned by a man named Jerry Brown, the Challenger’s unique setup was featured in the Seattle Times and numerous travel publications. Contemporary advertising described “yacht-like comfort” aboard the boat.

About 2002, the Challenger was sold and motored to Juneau. It was sold to Robinson in 2014 by Juneau resident Timothy Miles, who attempted to restore it. “A sad day!” he wrote on his Facebook page. “The Tugboat Challenger has sunk! It really breaks my heart, beyond words.”