The owner and operator of the boat that capsized earlier this week near Alcatraz Island said Thursday that his brother was killed and his sister, sister-in-law and a family friend remained missing after what began as a family trip to spread a relative’s ashes.

“It’s been horrible,” John Boisa said in a brief interview.

His comments came as San Francisco police used sonar to search for the 49-foot Volare and recovered a body floating west of Treasure Island. Authorities had not identified the person as of early Thursday evening.

Police were alerted to the body shortly after 1 p.m. by a passing vessel. The agency said it was using “multiple boat-mounted sonar platforms” to search for the Volare, which sank in water roughly 130 feet deep between Alcatraz Island and San Francisco.

The search has been complicated by “strong tidal currents along with wind and weather challenges,” police said in a statement.

Twenty people were aboard the boat when a wave struck it shortly after 3:30 p.m. Tuesday, causing the vessel to list before rolling over and sending everyone into the water.

Clifford Boisa, the operator’s brother, was pulled from the water and later declared dead despite receiving CPR. Sixteen others were rescued by a flotilla of first responders and nearby boaters.

Still missing Thursday were Clifford Boisa’s wife, Jackie Boisa; John Boisa’s sister, Carol Boisa; and a family friend whom he identified only as “Tonda.”

In a text message to this news organization, John Boisa recalled Jackie Boisa as possessing “a rare combination of easy acceptance of others with a kind of elegant sophistication.”

“She was simply a Lady and conducted herself in accordance with the highest meaning of that term,” he wrote.

He remembered his sister as bringing “her own special flavor to family gatherings and the earthy, natural joy she brought was ineffable.”

“I was especially pleased to see her enjoy our boating in recent years, and her smiles in photographs were genuine and without affectation,” he added. “I wanted for her and her children happiness and ease, and now, peace.”

Boisa, a Stockton-based consultant, said he had known Tonda only a short time but recalled her as “a generous, welcoming and gracious person.”

“I wish I knew her better, and I pray for peace and healing for her family,” he wrote.

Boisa described himself as the “vessel operator” and said Tuesday’s outing was “a family gathering” that included spreading the ashes of a relative who had died “a long time ago.”

Two days after the disaster, more details emerged about the boat, its weeklong stay in San Francisco and its final hours on the water.

The Volare, a 1981 Marine Trader Pilot built in Taiwan with a fiberglass hull, was based at Village West Marina & Resort, according to Tamara Barak Aparton of the San Francisco Recreation and Parks Department.

John Boisa received a guest permit to berth the boat at the city’s Marina Yacht Harbor from July 11 through Thursday, Aparton said. He had previously stayed at the harbor, though details about those visits were not available Thursday.

The vessel left the harbor around 10:15 a.m. Tuesday and traveled beneath the Golden Gate Bridge into the Pacific Ocean, according to the tracking website VesselFinder. It turned around about an hour later off Lands End and the Sutro Baths before returning to the bay at a slower speed.

The boat appeared to stop at Ayala Cove on the northwest side of Angel Island, leaving shortly after 3 p.m. and heading back toward the harbor, tracking data showed.

The Coast Guard’s search for survivors covered 950 square nautical miles before ending Wednesday evening. As police continued the recovery effort Thursday, maritime experts said they expected a lengthy investigation into how a vessel such as the Volare could capsize.

The Volare — a monohull recreation craft complete with two walled-off cabin levels and a deck top — was intended to handle waters such as San Francisco Bay, said Eric C. Jones, a retired Coast Guard rear admiral and superintendent of the Cal Poly Maritime Academy in Vallejo. Still, he said it was “unusual” for such a vessel to flip over in the bay.

Investigators are likely to examine whether the boat was properly maintained and operating correctly, and whether it could safely carry 20 people, Jones said. They also are expected to scrutinize the weather and water conditions that day and how the boat was operated in that environment.

The area where the Volare sank can be among the most challenging to navigate in the bay because of its distinctive winds and currents, said John Arndt, who has sailed the bay for more than 40 years and spent the past decade as publisher of the Northern California sailing magazine Latitude 38.

Arndt called the area “the playground of sailing” and compared portions of the bay to a ski hill, with some areas better suited to beginner and intermediate boaters. The area where the Volare sank could be compared to a black diamond ski run, he said: a more “challenging” section but one that is navigable for people experienced with those waters and conditions.

July and August are generally the windiest months on the bay, a result of hot air rising over the Central Valley and pulling cooler air from the Pacific Ocean through the bay’s narrow entrance. While winds can remain manageable in some areas, the central channel between Angel Island and San Francisco can experience strong sustained winds and gusts.

The water can become particularly choppy when westerly winds collide with an outgoing tide. Water flowing from the Sacramento and San Joaquin river valleys toward the Pacific further complicates the currents in that area.

Arndt called a disaster of this magnitude involving this type of boat “exceptionally rare.” He said Tuesday’s conditions were not outside the normal range for summer boating on the bay.

“When people analyze accidents and disasters, it’s not one thing — it’s sort of these things that tend to be a spiral of events,” Arndt said.

Jakob Rodgers is a senior breaking news reporter. Call, text or send him an encrypted message via Signal at 510-390-2351, or email him at jrodgers@bayareanewsgroup.com.

SAN FRANCISCO (KGO) — Two commercial fishermen described the desperate rescue efforts they undertook after a three-level vessel sank in San Francisco Bay with 20 people on board, leaving several people trapped and others struggling in the water.

Mike Montoya and Justin Marceline said they had not planned to be on the water Tuesday but made a last-minute decision to go fishing.

While out on the bay, they noticed what they described as smoke or steam about two miles away and headed toward it. When they arrived, they found a vessel rapidly sinking and passengers fighting to survive.

“Moments of chaos” unfolded as people jumped into the freezing water, clung to the side of the boat and yelled for help, according to the fishermen.

“She didn’t have a lifejacket, and she was flailing, and I grabbed her by the arm and pulled her up. The imagine is etched in my mind. She had bright blue eyes and she looked up at me and said help, and I was like, ‘You look like my mom. I’m not going to let you go. I promise you.’ She told me she didn’t want to die, and I told her ‘I’m not going to let you die,’” Marceline said.

Crews will suspend search for 3 missing in deadly SF Bay boat sinking Wednesday evening

Montoya and Marceline said they were the first to arrive at the scene and rescued eight or nine people from the water before first responders reached the area.

“The boat was already sinking. It was about halfway in the water. I say they were on their knees in the second deck in the gally. Within a minute they were up to their shoulders,” Marceline said.

Montoya said getting close enough to rescue victims was difficult because of the debris scattered across the water.

“Yes, there was so much debris on the water and people and stuff everywhere. I couldn’t tell what was a person and what wasn’t, and I was maneuvering the boat in and out, and we would grab a person and back up and see who the next person to grab was,” Montoya said.

Within minutes, they said, first responders from across the Bay Area arrived with divers and rescue crews, joining the effort to save those on board. But both men said the most haunting images were of people they could not reach in time.

“There was one window open and when we pulled on the scene, Mike said, ‘There are people in there banging. The window — break the window!’ and like I said, there were mostly older people, and they couldn’t break the window. It was a helpless feeling,” Marceline said.

“Can’t even imagine. We were throwing weights at the window and handed a guy a weight here break the window or kick the window and he looked at us like, ‘I’m exhausted. Can’t do anything,’” Montoya said.

Marceline compared the scene to a maritime disaster.

“It was a scene from the Titanic in real life. Like people banging on the window trying to get out. It’s probably something I will never forget,” he said.

Sudden immersion in water under 60 degrees Fahrenheit (15 degrees Celsius) can lead to cold water shock, a condition where people lose dexterity in minutes. That can be dangerous or deadly when trying to escape a sinking watercraft.

As of Wednesday, dive teams continued searching for three people who remained missing following the sinking.

U.S. Coast Guard crews combed cold, choppy waters in and around San Francisco Bay on Wednesday for the three people missing nearly a day after the boat capsized with 20 family members and friends aboard to scatter the ashes of a loved one.

Ralph Boisa said his extended family and a few close friends were on his younger brother’s boat Tuesday afternoon to celebrate the life of his daughter who died at age 33 in 2016 and loved to surf.

His older brother, Clifford, died shortly after being pulled out of the water. Sixteen others were rescued as the cabin cruiser took on water, listed heavily to one side and rolled over before sinking. Clifford’s dog also died.

The three people missing are his sister Carol, Clifford’s wife Jackie, and his daughter’s friend, he said.

“We’ve gone through a lot of tragedy over the years,” said Boisa, who lost his other daughter in 1995. He lives in Washington and couldn’t make it for the excursion.

The Associated Press contributed to this report.

SAN FRANCISCO – While one person died after a cabin cruiser sank in the San Francisco Bay on Tuesday afternoon, a harrowing rescue near Alcatraz Island saved 16 lives.

The U.S. Coast Guard and the San Francisco Fire Department continue to search for three missing people who went overboard after the vessel went down around 3:30 p.m.

Clifford Joseph Boisa, 79, of Sutter County, was pronounced dead following the incident. However, 16 others were brought to safety, many of them rescued by civilian boaters who rushed to help. Among the Good Samaritans were fishermen Mike Montoya and Justin Marceline, who were aboard the Khea, a 22-foot Boston Whaler.

At a Wednesday afternoon press conference, Coast Guard Incident Commander Jarod Toczko praised the fishermen and a nearby kiteboarder for their heroic actions.

A rush to help

Dig deeper:

Montoya and Marceline were on the water when they noticed signs of trouble nearby.

“I turned around and I saw a plume of either smoke or steam,” Montoya said. “I just knew that somebody was in distress.”

Montoya told his partner they needed to move their boat closer to investigate. When they arrived, they found people struggling to stay afloat in the Bay’s frigid waters.

The rescuers began throwing life jackets and flotation devices to those in the water, pulling victims aboard as quickly as possible. Many of the victims were exhausted and unable to pull themselves out of the water.

Witnesses recount people ‘trapped’ inside

What they’re saying:

As they pulled survivors aboard, Montoya said he saw people trapped inside the cabin of the sinking vessel, banging on the windows.

“We were throwing fishing weights at the window, trying to get it to break, and we handed a guy a fishing weight that was in the water, and he didn’t have a life jacket on,” Montoya said.

In total, Montoya and Marceline pulled nine people onto their boat and brought them to safety.

Marceline was prepared to jump into the Bay to help more victims, but Montoya stopped him, warning of debris and other dangers beneath the surface.

“My first thought was to kick my shoes off and get down to my underwear and jump in and start to get the elderly people off the boat, because it was elderly people helping elderly people and it wasn’t going fast enough,” Marceline said.

Memorial service turns tragically fatal

Survivors told the fishermen they had gathered on the water for a memorial service. Authorities later confirmed that the victims and survivors were relatives and close friends holding a memorial when the boat went down.

Toczko said the 50-foot cabin cruiser was capable of carrying the number of people on board, but noted that investigators must consider several factors regarding the boat’s stability.

The investigation into what caused the vessel to sink is ongoing.