WEST PALM BEACH, Fla. (KRON/CNN) — The Coast Guard continued an intense search off Florida’s Atlantic coast for two teenage boys missing at sea since they set off for a fishing trip on Friday.

The day-and-night search is focused 60 to 70 miles off Jacksonville, north of where the boys’ capsized boat was found on Sunday. Coast Guard officials say the boat did not appear damaged and no foul play is suspected. But as each day passes, the concern is that the chances of survival are diminishing.

In the warm waters off Florida this time of year, the Coast Guard says, someone can survive four, maybe five days. Capt. Mark Fedor, chief of response for the Coast Guard 7th District said that water is relatively warm, but “it’s a dangerous environment, and there’s only so long you could stay in the water.”

14-year-old stepson Perry Cohen and his friend Austin Stephanos were last seen Friday afternoon buying $110 worth of fuel near the town of Jupiter. They got on the water in a 19-foot, single-engine center-console vessel. Later that day, when one of the boys’ grandmothers didn’t hear from them, she reported them missing.

Perry Cohen’s stepfather Nick Korniloff said the boys were supposed to remain on the Loxahatchee River and the Intracoastal Waterway during their outing. He said that they obviously ended up in the deep waters they were supposed to steer clear of.

The Coast Guard said five cutters, a Navy ship and multiple planes are involved in the search.

The boys’ mothers say they continue to hold out hope that search crews will bring their sons home. “They’ve brought out every resource they have,” Carly Black, Austin’s mother, said of the Coast Guard. “They’re using everything they have to find our boys. They truly believe they’re going to find them.”

While the boys are young, they were legally operating the boat. Florida regulations say a person must be at least 14 to operate a watercraft.

“Both boys are very, very comfortable on the water,” said Perry’s mother, Pamela Cohen. “We’ve both always said that they’re just as comfortable on a boat and the water as they are on land.”

The teens’ families are offering a $100,000 reward in the search and a famous neighbor – NFL Hall of Famer Joe Namath – promised to continue searching local beaches in hopes of finding clues.