OCEAN CITY, N.J. - In 114 years, no one has drowned on their watch.

But once the 154 members of the Ocean City Beach Patrol are off duty - especially when the weather is tropical, the water is unseasonably warm, and sunset is still hours away - bathers put their lives in danger.

Elsewhere on the Jersey Shore, five fatalities related to rip currents have been reported in recent weeks, according to authorities. In most cases, the deaths happened where guards had packed up for the day.

Anticipating the crush of bathers that comes during the high season, the Ocean City patrol has expanded its presence on three downtown beaches.

Guards will remain on duty on the Eighth, Ninth and 12th Street beaches until 8 p.m. Fridays, Saturdays, and holidays, and a new, four-member Rapid Response Team will be stationed at the squad's 12th Street headquarters to help police and fire personnel with water rescues.

Staff will leave those locations at the regular closing time of 5 p.m. Monday through Thursday and 5:30 p.m. Sunday.

Ocean City has lifeguard stands on 43 of its 60-plus beaches, giving the resort the largest protected beachfront on the southern Shore.

"I can't see how this isn't going to be successful in keeping people safe," Beach Patrol Chief Tom Mullineaux said Friday.

From Sea Bright to Cape May, 5 to 6 p.m. is traditionally when guards shoo swimmers from the surf with whistles and bull horns. Cape May keeps patrol members at the squad's headquarters until several hours later to help police with beachfront safety matters. But with its extended hours at selected beaches - which went into effect last weekend - no Jersey Shore town offers lifeguard-protected bathing later than Ocean City, Mullineaux said.

Most Shore beaches say they officially close at 9 or 10 p.m. There are no ordinances to prevent swimming, however.

"We tell them to stay out of the water, recommend that they don't swim without a lifeguard. What happens after we leave . . . well, that's up to them," Mullineaux said.

With ocean temperatures hovering around 70 for the last month, an evening dip is alluring to bathers, especially during a heat wave.

But late in the day can be particularly dangerous: The tide changes and the surf begins to kick up, often creating rip currents that quickly pull a bather from shore.

"Because of the nice weather, we've already had a couple of situations down around 12th Street where we've had to pull people out after hours because of the rips," Mullineaux said. "It can get rough out there very quickly."

Early this month, a week of steady northeast winds led to particularly rough surf and deep rip currents along Ocean City's eight miles of beach, Mullineaux said.

Concern this year about rip currents has led the nonprofit New Jersey Sea Grant Consortium to team with Stevens Institute of Technology to generate public awareness of the phenomenon and develop technology to help prevent drownings.

"We want to remind people that rip currents are potentially one of the deadliest natural phenomena," said Jon Miller, a Stevens professor and coastal expert. "They tend to receive far less publicity then other dangers because our understanding of them has been so limited."

Graduate students at Stevens, in Hoboken, have developed a smartphone application based on information from lifeguards who identify rip currents in real time. The data can help guards at nearby locations make decisions about whether to allow swimmers at their beaches, officials said.

Contact Jacqueline L. Urgo at 609-652-8382 or jurgo@phillynews.com. Read the Jersey Shore blog "Downahore" at www.philly.com/downashore.