The Navy has joined the search for two teenage boys who disappeared off the coast of Florida during a fishing trip Friday, adding the USS Carney to a Coast Guard search team that has covered about 29,000 square nautical miles — by air and sea — in the hunt for Austin Stephanos and Perry Cohen.

The search has taken on extra urgency after the Coast Guard located the boat the two boys had been using. The capsized vessel was discovered Sunday about 67 nautical miles off Ponce de Leon Inlet in Volusia County, but there was no sign of Stephanos or Cohen, both 14, in or around the boat, according to the Associated Press.

“None of us are giving up hope they’re going to find those boys,” Perry’s mother, Pamela Cohen, told CNN on Monday. “Obviously, it’s a terrifying experience to be living through.”

She added: “I don’t know what happened; none of us know what happened. If we did, we’d have them in our arms right now.”

[Marine experts say missing Fla. teenagers should not have been alone offshore]

Football legend Joe Namath, a neighbor who knows both teenagers, is offering a $100,000 reward for the boys’ safe return.

The boys — who were heading in the direction of the Bahamas — were last seen at a marina in Jupiter, Fla., at about 1:30 p.m. Friday, when they bought $110 worth of fuel for their 19-foot, white single-engine vessel, authorities said.

On Sunday, an MH-60 Jayhawk rescue helicopter crew from Air Station Clearwater located the boat.

Police from Tequesta told the Palm Beach Post that the Coast Guard said the “engine cover was found to be missing along with one Personal Floatation Device (PFD) still on the boat.”

“We’re continuing the search and we maintain the highest level of optimism going into this,” Navy Petty Officer 1st Class Stephen Lehmann said at a Monday briefing, according to Fox News.

On Instagram, Pamela Cohen posted a photo of her son, writing: “Everyone is awaiting your safe return my sweet boy. There are literally millions of people praying for you and Austin to stay strong and hold on! We all miss you guys so much! Never stop believing!!!!!”

The teenagers, whose families live across the street from each other in Tequesta, were last heard from about 11 a.m. on Friday, when they checked in with their parents. Stephanos and Cohen were posting photos of the boat and their fishing gear on Snapchat about an hour later, ABC News reported.

Relatives said the boys were headed east, toward the Bahamas.

Family members told the Palm Beach Post that in the past, the boys were “conscientious” about checking in, even during trips to the mall. The relatives began to worry when they couldn’t reach the boys Friday afternoon. The boys’ parents reported them missing about 5 p.m. Friday, authorities said.

“I really don’t know where the water has taken them,” Carly Black, Austin’s mother, told the newspaper on Saturday. “I know they’re out there, they’re safe, and we just need to bring them home.”

Perry’s stepfather, Nick Korniloff, told ABC News that the families don’t know how much food and water the boys have but said he is confident that they “know what they’re doing out there.”

Searchers are considering multiple variables in the teenagers’ disappearance, including weather, currents and the conditions of the water.

“We are very much hopeful they are okay and we can bring them back home,” Coast Guard Petty Officer Mark Barney said. “This is still a search and rescue mission.”

Relatives held out hope for the teenagers’ safe return. They said both are strong swimmers who grew up on the water fishing, swimming and operating watercraft. Both families also have vacationed on the islands 85 miles east of Palm Beach County, according to the Palm Beach Post.

“Both boys have their boaters certification,” Pamela Cohen told ABC News. “Perry has been on a boat really since he was 7.”

“[For] Austin, this is his fourth boat,” Black added. “He’s been around boats since before he could walk.”

Austin’s mother told the Palm Beach Post that her son has two brothers, ages 10 and 2½ years old, who are waiting for him to return.

Family members told the newspaper that Perry recently finished middle school. He enjoys fishing, skateboarding and playing sports, they said.

On Sunday, more than 200 family friends, classmates and others gathered at Jupiter Christian School for a prayer vigil, according to the Palm Beach Post. Stephanos has attended the school since kindergarten, the newspaper reported.

“I think all of us who know Austin and know Perry know that they would want us to hold onto hope and remain joyful,” Kaitlin Riceputo, a fourth-grade teacher, told the newspaper.

“Please Lord, find Austin and Perry,” said Jim Colman, the school’s president. “Bring them home safe.”

This post, originally published on July 27, has been updated.

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